EnergyPlus University Course

Introduction to Building Simulation and EnergyPlus Undergraduate Course Curriculum Information July 31, 2003

Intent The intent of this document is to present a draft curriculum outline for an undergraduate course that teaches the student about the usage of EnergyPlus. While not all of the curriculum will necessarily be specific to the EnergyPlus program, the vast majority is intended to instruct the student on how EnergyPlus works and what information it needs as input and provides as output.

Assumptions Every university is slightly different in how it approaches courses, and every instructor will approach a course differently as well. Several assumptions will be made that will help focus the development of this course: • This course is intended to be taught primarily to upper-level undergraduate students at the (USA) university level but could also be taught at the graduate level. • The primary audience is a student in mechanical or architectural engineering who has had background courses in heat transfer and thermodynamics. Instructors in affiliated fields such as civil engineering, architecture, etc. may need to supplant some of the lecture material with more basic information on heat transfer, thermodynamics, engineering analysis, etc. • This course is designed for a university on the semester system where a semester lasts approximately 15 weeks. • The lectures will be designed for a traditional 50-minute lecture period and three class sessions per week will be assumed. • It is imperative that students spend supervised time in computer laboratories to gain more experience using the program and the input language. Thus, some of the class periods will be assumed to meet in a computer laboratory rather than a lecture hall. • Based on the assumptions of 15 weeks and 3-50minute class periods per week, a total of 45 class sessions are available for course introduction, lectures, laboratories, reviews, exams or presentations, etc. • Since there is currently no interface for EnergyPlus, the lectures will be developed without referring to any interface. The IDF Editor and EP-Launch can be used in computer laboratories as desired. Existing templates may also be utilized. • Complete expertise in EnergyPlus cannot be gained in a single semester. Thus, this course will strive to give the student a working knowledge of most features of

•

the program rather than expertise in a specific area. Again, no interface will be assumed (this affects what material must be covered in the lectures). Lectures must also provide adequate enough background about what is being simulated so that the students understand “what” not just “how”.

General Breakdown of Class Sessions Based on the assumptions listed in the previous section, the following breakdown of the 45 class sessions can be made. The main focus of this project is to develop the lectures and example assignments. Course syllabi, exams, homework assignments, reviews, course evaluations, etc. are left to the discretion of the individual instructors who will have specific ideas, formats, etc. about what these should be and look like. • Course Syllabus and Class Overview—1 Session • Formal Lectures (PowerPoint Slide Shows Provided)—26 Sessions • Computer Laboratories (Example Exercises to be developed by Instructor, see section later in this documents for more notes on this)—14 to 15 Sessions, some of which may be used as semester project work sessions • Exams and/or Presentation of Semester Projects—2 to 3 Sessions • Final Review, Course Evaluations, Wrap-up—1 Session

Class Outline/Schedule (With Semester Projects) In many cases, the lessons learned and knowledge gained by a course in EnergyPlus is best applied not only through application assignments but also a semester project that deals with using EnergyPlus. The main goal would be to demonstrate the use of EnergyPlus to model an existing building or a building design. Instructors could also require students to compare the results with measured building data and/or perform the analysis or retrofit or design options to improve the overall performance of the building. The following schedule is intended to work with a course that uses a project to test student comprehension rather than exams. Obviously, individual instructors are free to adapt the schedule and lecture material as they see fit. In some cases, instructors may wish to use the example assignments sparingly and focus more on student projects. Note that an accompanying spreadsheet contains the number of slides for each of the individual lectures. Note that some lectures are too long to cover in one hour and this may require an adjustment of the schedule. Lectures 4 and 14 are examples of lectures that may require two hours to cover. Again, discretion is left up to the individual instructor as to whether material will be skipped or lectures will be enhanced. Thus, the schedule is merely a starting point that will need to be customized. Computer laboratories may include activities other than input file creation (such as looking up and/or downloading weather data or documentation, research on materials or construction techniques, etc.) Week Week 1

Class Type General

Description Class Overview and Discussion of Course Syllabus

Week 1 Week 1 Week 2 Week 2 Week 2 Week 3 Week 3 Week 3 Week 4 Week 4 Week 4 Week 5 Week 5 Week 5 Week 6 Week 6 Week 6 Week 7

Week 7 Week 7 Week 8 Week 8 Week 8 Week 9 Week 9 Week 9 Week 10 Week 10 Week 10 Week 11 Week 11 Week 11 Week 12 Week 12 Week 12

Lecture 1

EnergyPlus Overview (Program History, Files Overview, Web Resources) Computer Laboratory 1 Intro to/Demo of IDF Editor/EP-Launch/Install Lecture 2 Running EnergyPlus and Output Lecture 3 Output Variables, Meters, Reports Computer Laboratory 2 Introduction to Output Lecture 4 Simulation control, weather, location, ground temperature Lecture 5 Materials, Constructions, Surfaces, Zones, Buildings Computer Laboratory 3 Run Control and Weather Information Exercise Lecture 6 Materials, Constructions, Surfaces, Zones, Buildings Lecture 7 Building Modeling Questions Computer Laboratory 4 Building Envelope Exercise Lecture 8 Schedules, Internal Gains, Infiltration Lecture 9 Windows, Daylighting Computer Laboratory 5 Scheduled Heat Gains and Zone Controls Exercise Lecture 10 Zone and Modeling Controls, Purchased Air Lecture 11 Simple Ventilation, Mixing/Cross Mixing, COMIS Computer Laboratory 6 Windows and Daylighting Exercise Lecture 12 Green Input: Trombe Wall, Movable/Transparent Insulation, Thermal Mass, etc. Lecture 13 Loops, Nodes, Branches, Connectors Computer Laboratory 7 Air Movement and Green Features Exercise Lecture 14 Air Loops and Zone Equipment Lecture 15 Air Loops and Zone Equipment Computer Laboratory 8 Semester Project Work Session Lecture 16 Air Loops and Zone Equipment Lecture 17 Air Loops and Zone Equipment Computer Laboratory 9 Air Loops and Zone Equipment Exercise Lecture 18 Templates and Autosizing Lecture 19 Outside Air Computer Laboratory 10 Semester Project Work Session Lecture 20 Radiant Systems Lecture 21 Plant/Condenser Loops and Equipment Computer Laboratory 11 Radiant System Exercise Lecture 22 Plant/Condenser Loops and Equipment Lecture 23 Plant/Condenser Loops and Equipment Computer Laboratory 12 Plant and Condenser Loop Exercise

Week 13 Week 13 Week 13 Week 14 Week 14 Week 14 Week 15 Week 15 Week 15

Lecture 24 Lecture 25 Lecture 26 Computer Laboratory 13 Computer Laboratory 14 Computer Laboratory 15 Project Presentations Project Presentations General

Ground Heat Transfer TBD or Catch up/Lecture 4b TBD or Catch up/Lecture 14b Semester Project Work Session Semester Project Work Session Semester Project Work Session In-Class Presentations By Students In-Class Presentations By Students Final Review, Course Evaluations, Class Wrapup

Class Outline/Schedule (With Exams/Quizzes) The content and goals for this class are the same as for the project class except that exams are used to further and test student comprehension of EnergyPlus. However, the schedule is slightly altered to allow time for exams. Week Week 1

Class Type General

Week 1

Lecture 1

Week 1 Week 2 Week 2 Week 2 Week 3

Computer Laboratory 1 Lecture 2 Lecture 3 Computer Laboratory 2 Lecture 4

Week 3

Lecture 5

Week 3 Week 4

Computer Laboratory 3 Lecture 6

Week 4 Week 4 Week 5 Week 5 Week 5 Week 6

Lecture 7 Computer Laboratory 4 Lecture 8 Lecture 9 Exam 1 Computer Laboratory 5

Week 6 Week 6

Lecture 10 Lecture 11

Week 7

Computer Laboratory 6

Description Class Overview and Discussion of Course Syllabus EnergyPlus Overview (Program History, Files Overview, Web Resources) Intro to/Demo of IDF Editor/EP-Launch/Install Running EnergyPlus and Output Output Variables, Meters, Reports Introduction to Output Simulation control, weather, location, ground temperature Materials, Constructions, Surfaces, Zones, Buildings Run Control and Weather Information Exercise Materials, Constructions, Surfaces, Zones, Buildings Building Modeling Questions Building Envelope Exercise Schedules, Internal Gains, Infiltration Windows, Daylighting Scheduled Heat Gains and Zone Controls Exercise Zone and Modeling Controls, Purchased Air Simple Ventilation, Mixing/Cross Mixing, COMIS Windows and Daylighting Exercise

Week 7

Lecture 12

Week 7 Week 8 Week 8 Week 8 Week 9 Week 9 Week 9 Week 10 Week 10 Week 10 Week 11 Week 11 Week 11 Week 12 Week 12 Week 12 Week 13 Week 13 Week 13 Week 14 Week 14 Week 14 Week 15 Week 15 Week 15

Lecture 13 Computer Laboratory 7 Lecture 14 Lecture 15 Computer Laboratory 8 Lecture 16 Lecture 17 Exam 2 Computer Laboratory 9 Lecture 18 Lecture 19 Computer Laboratory 10 Lecture 20 Lecture 21 Computer Laboratory 11 Lecture 22 Lecture 23 Computer Laboratory 12 Lecture 24 Lecture 25 Exam 3 Lecture 26 Computer Laboratory 13 Computer Laboratory 14 General

Green Input: Trombe Wall, Movable/Transparent Insulation, Thermal Mass, etc. Loops, Nodes, Branches, Connectors Air Movement and Green Features Exercise Air Loops and Zone Equipment Air Loops and Zone Equipment Air Loops and Zone Equipment Exercise Air Loops and Zone Equipment Air Loops and Zone Equipment Air Loops and Zone Equipment Exercise Templates and Autosizing Outside Air Air Loops, Templates, and Autosizing Exercise Radiant Systems Plant/Condenser Loops and Equipment Radiant System Exercise Plant/Condenser Loops and Equipment Plant/Condenser Loops and Equipment Plant and Condenser Loop Exercise Ground Heat Transfer TBD or Catch up/Lecture 4b TBD or Catch up/Lecture 14b Independent Research Assignment Independent Research Assignment Final Review, Course Evaluations, Class Wrapup

Lecture Examples and Homework Assignments Examples and case studies have been used through the lectures to provide the students with some insight into the workings of EnergyPlus and also to initiate discussions between the instructor and the students. The lectures do not claim to be exhaustive in covering every detail that could potentially be investigated or discussed in class. Some examples might be overly complex for some of the students. Instructors may wish to replace examples and case studies with ones from their own course material or create new ones that focus on more specific topics or that allow a particular effect to be analyzed. Instructors may also wish to assign simpler examples or targeted case studies as homework assignments—allowing the students to gain experience with the program and to take time outside of class to think through particular issues involved with simulating buildings.

In addition, while is some cases, instructors will have homework assignments and examples that used other simulation programs which they wish to convert to EnergyPlus examples, other instructors may not have a “library” of examples and homework assignments. The lectures developed for this university course were a part of a larger research project that also developed lectures for professionals. These professional series lectures also included workshops that could be used as homework assignments. Information on where to locate these workshops should be available at the NREL web site.

Concluding Comments We hope that you enjoy the lectures provided in this course and will find them useful in your teaching efforts. You may only use part of the material for an unrelated course, you may use the lectures as they are, or you may modify/enhance the lectures to suit the particular focus of your course. The authors of this lecture series hope that instructors using these materials will share their experiences and improvements with NREL so that others instructors and the students can benefit from the collective body of knowledge in this area.

Lecture 1: An Overview of Simulation and EnergyPlus

Material prepared by GARD Analytics, Inc. and University of Illinois at Urbana-Champaign under contract to the National Renewable Energy Laboratory. All material Copyright 2002-2003 U.S.D.O.E. - All rights reserved

Purpose of this Lecture Gain an understanding of 

Simulation as a Concept



EnergyPlus as a Simulation Tool

Briefly review topics important to your

understanding of building thermal simulations

2

What is Simulation? Definition: “the imitative representation

of the functioning of one system or process by means of the functioning of another ” (Merriam-Webster Dictionary On-Line)

3

What is Building Thermal Simulation? Approximate definition: a computer

model of the energy processes within a building that are intended to provide a thermally comfortable environment for the occupants (or contents) of a building Examples of building thermal simulation programs: EnergyPlus, Energy-10, BLAST, DOE-2, esp-R, TRNSYS, etc. 4

Goals of Building Thermal Simulation Load Calculations 

Generally used for determining sizing of equipment such as fans, chillers, boilers, etc.

Energy Analysis 

Helps evaluate the energy cost of the building over longer periods of time

5

Why is Simulation Important? Buildings consume roughly one-third of

all the energy consumed nationally every year 

Much of this energy is consumed maintaining the thermal conditions inside the building and lighting

Simulation can and has played a

significant role in reducing the energy consumption of buildings 6

How does Simulation save Energy?  Building thermal simulation allows one to

model a building before it is built or before renovations are started  Simulation allows various energy alternatives to be investigated and options compared to one another  Simulation can lead to an energy-optimized building or inform the design process  Simulation is much less expensive and less time consuming than experimentation (every building is different) 7

Quick Review of Important Background Concepts  Control Volumes and the Conservation of:  Mass  Energy (First Law of Thermodynamics)  Heat Transfer Mechanisms:  Conduction—transfer of thermal energy through a solid  Convection—exchange of thermal energy between a solid and a fluid that are in contact  Radiation—exchange of thermal energy via electro-magnetic waves between bodies or surfaces 8

What is EnergyPlus? Fully integrated building & HVAC

simulation program Based on best features of BLAST and DOE-2 plus new capabilities Windows 95/98/NT/2000/XP & Linux Simulation engine only Interfaces available from private software developers 9

EnergyPlus Concepts  Time dependent conduction 



Conduction through building surfaces calculated with conduction transfer functions Heat storage and time lags

 Migration between zones 

Approximates air exchange using a nodal model

 Only models what is explicitly described  

Missing wall does not let air in Missing roof does not let sun in 10

EnergyPlus Concepts (cont’d)  Heat balance loads calculation (one of two load

calculation methods recommended by ASHRAE)

 Moisture balance calculation  Simultaneous building/systems solution  Sub-hourly time steps  Modular HVAC system simulation  WINDOW 5 methodology

11

EnergyPlus Concepts (cont’d) Simple input/output file structures No surface, zone or system limits 

Defaults to 50 coils per HVAC loop



Can be increased

Links to other software 

COMIS, wind-induced airflow



TRNYSYS, Photovoltaics 12

EnergyPlus Structure

13

Integrated Simulation Manager Fully integrated simulation of loads,

systems and plant 



Integrated simulation allows capacity limits to be modeled more realistically Provides tighter coupling between the airand water-side of the system and plant

14

Integrated Simulation Manager (cont’d)

15

Input/Output Data  EnergyPlus input and output data files

designed for easy maintenance and expansion  Will accept simulation input data from other sources such as CADD programs (AutoCAD, ArchiCAD, Visio), and preprocessors similar to those written for BLAST and DOE2  An EnergyPlus input file is not intended to be the main interface for typical end-users

16

Input/Output Data (cont’d) Most users will use EnergyPlus through

an interface from a third-party developer Utilities convert portions of BLAST and DOE2 input to EnergyPlus input 

Materials and constructions



Schedules



Building envelope surfaces

17

Summary  EnergyPlus builds on the strengths of BLAST

and DOE-2 and includes many new simulation capabilities: 

 



Integrated loads, system and plant calculations in same time step. User-configurable HVAC system description. Modular structure to facilitate the addition of new simulation modules. Simple input and output data formats to facilitate graphical front-end development. 18

Basic Input and Output Issues General Philosophy Input/Output Files Overall File Structures Input Object Structure Input Data Dictionary (IDD) Weather Files

19

General Philosophy of Input/Output/Weather  Simple, free-format text files  SI units only  Comma-separated  Object-based  Somewhat self-documenting  Two parts—dictionary and data or simulation

results  Not user-friendly » Interfaces will help  Can become large

20

Input–Output Files Input Data Dictionary (IDD)

Main Program

Input Data Dictionary This file is created by EnergyPlus developers.

Module

Module

Module

Module

Module

Module

Input Data Files (IDF) Input Data File This file will be created by User Object,data,data,…,data; Object,data,data,…,data;

Output Processor

EnergyPlus Program

Output Files File Types: Standard Reports Standard Reports (Detail) Optional Reports Optional Reports (Detail) Initialization Reports Overview of File Format: Header Data Dictionary Data Note: These files will be created by EnergyPlus.

21

Input Object Structure  Begin with object type followed by comma  A (alpha) and N (numeric) fields in exact order  Fields separated by commas  Last field followed by semi-colon  Commas are necessary placeholders BASEBOARD HEATER:Water:Convective, Zone1Baseboard, FanAndCoilAvailSched, Zone 1 Reheat Water Inlet Node, Zone 1 Reheat Water Outlet Node, 500., 0.0013, 0.001;

!!!!!!!-

Baseboard Name Available Schedule Inlet_Node Outlet_Node UA {W/delK} Max Water Flow Rate {m3/s} Convergence Tolerance 22

Input Object Structure (cont’d)  Alpha fields 60 characters maximum  “!” exclamation point begins comments  IDF objects can be in any order  IDF Editor may rearrange the order  “!-” IDF Editor automated comments  IDF Editor cannot be used with HVAC Templates BASEBOARD HEATER:Water:Convective, Zone1Baseboard, FanAndCoilAvailSched, Zone 1 Reheat Water Inlet Node, Zone 1 Reheat Water Outlet Node, 500., 0.0013, 0.001;

!!!!!!!-


Input Object Structure (cont’d)  Not case-sensitive  Input processor checks basic rules, A vs. N, number

of fields, valid object type, max/min, etc.  IDF objects are generally retrieved by each component simulation module BASEBOARD HEATER:Water:Convective, Zone1Baseboard, FanAndCoilAvailSched, Zone 1 Reheat Water Inlet Node, Zone 1 Reheat Water Outlet Node, 500., 0.0013, 0.001;

!!!!!!!-


Input Data Dictionary (IDD File)  Energy+.idd  Located in

EnergyPlus folder

 Conceptually simple  

A (alpha) or N (Numeric)

BASEBOARD HEATER:Water:Convective, A1 , \field Baseboard Name \required-field A2 , \field Available Schedule \required-field \type object-list \object-list ScheduleNames . . . N1 , \field UA \required-field \autosizable \units W/delK . . . N3 ; \field Convergence Tolerance \type real \Minimum> 0.0 \Default 0.001 25

IDD File (cont’d) Lists every available input object  



If it isn’t in the IDD, then it’s not available IDD version must be consistent with exe version IDD is the final word (even if other documentation does not agree)

26

IDD File (cont’d) “\”code Specifications 

Field descriptions



Units



Value ranges (minimum, maximum)



Defaults



Autosizing

27

IDD File (cont’d) Get to know the IDD file Easy way to quickly check object syntax Refer to Input Output Reference for

detailed explanations of inputs

28

Allowable Ranges and Defaults  Allowable ranges  Some max/min declared in IDD  Fatal error if outside of range 

Some max/min hidden in source code  May reset value and issue warning, may be fatal

 Defaults  Some defaults declared in IDD  Some defaults hidden in source code  Some values have no defaults  Alphas become blank  Numerics become zero 29

Weather Data (epw file) Weather year for energy use

comparisons, similar to other programs Hourly, can be subhourly Hourly data is linearly interpolated Data include temperature, humidity, solar, wind, etc. Several included in standard install 30

Output Data Format Same philosophy as for input;

somewhat human readable output files EnergyPlus can perform some output processing to help limit output size User definable variable level reporting

31

Output Reporting Flexibility User can select any variables available

for output User can specify output at time step, hourly, daily, monthly, or environment intervals User can schedule each output variable User can select various meters by resource and end-use 32

Questions How long will my simulation take?  Depends on size of input file, length of simulation period (day vs. year), and speed of computer  Might range from a few seconds to several minutes (some detailed simulation modules may require even longer)  EnergyPlus will display progress in a window on the desktop so that the user knows where it is at 33

Questions (cont’d)  How do I know whether the program read my input

correctly? 



Take a look at the .EIO file (EnergyPlus initialization output)—this may indicate that you have misinterpreted an input parameter Check results output files and see if they are reasonable

 How will I know whether my simulation results are

reasonable or outrageous?  

 

See previous question Consider “Load Check Figures” available from sources such as ASHRAE Compare to other simulations or consult your instructor Do some simple hand calculations (such as UA∆T) and see if the numbers are “in the ballpark” 34

Computer Laboratory 1: Installing and Using EnergyPlus


Purpose of this Lecture Gain an understanding of 

How to Install EnergyPlus



How to Use EnergyPlus



Auxiliary Programs and Documentation for EnergyPlus

2

Installing EnergyPlus EnergyPlus Components EnergyPlus Folders

3

Installing EnergyPlus Select Components Menu 

Documentation



EP-Launch

1819k



IDFEditor

415k



SampleFiles



WeatherConvertor

2428k



BLASTTranslator

4978k



DOETranslator

663k

GroundHeatTransferPreProcessor

770k

IFCtoIDF 

12759k

29065k

2910k

Included in default installation

4

Installing EnergyPlus (cont’d)  After installation the EnergyPlus directory will

contain the following subdirectories (if default components are selected):     

BACKUP DataSets Documentation Example Files PostProcess

   

PreProcess Templates Trnsysspv WeatherData

5

EnergyPlus Folders EnergyPlus 

Location selected during install



Default is c:\EnergyPlus



Batch files



Executables



Readme

6

DataSets Folder  DataSets –

Predefined Objects      

Locations Design Days Materials Constructions Schedules and more

 MacroDataSets  ##if blocks for parametric batch runs

7

Documentation Folder  Documentation 



  

User & Developer Documentation Bookmarks to Navigate Searchable PDF Format Requires Acrobat Reader 5.0 or higher (www.adobe.com)

8

ExampleFiles Folder ExampleFiles 



 

Dozens of example inputs Named by key feature e.g., CVBbRh.idf Many concepts are best learned by example

9

WeatherData Folder  WeatherData 

User can download additional EPW weather files at www.energyplus.gov

10

Start Menu Shortcuts  Start  Programs 

EnergyPlus Vn-n-n Programs

 DocMainMenu 

Docs Menu Page

 EP-Launch 

Easy-to-Use Run Tool

 IDFEditor 

Input File Editor 11

Start Menu Shortcuts (cont’d) IFCtoIDF 

Convert IFC Files

WeatherConverter 



Process Weather Data Create Weather Reports

12

User Documentation  Eplus Main Menu

EnergyPlus\Documentation\ EPlusMainMenu.pdf  Start  Programs  EnergyPlus Programs  DocMainMenu Getting Started Input Output Reference Output Details and Examples Engineering Reference Auxiliary Programs/Developer Guides Frequently Asked Questions 

     

13

Auxiliary Tools Run-time Tools 

EP-Launch

Input/Output Tools 

IDF Editor



WinEPDraw

14

EP-Launch Assistance in running EnergyPlus Reads EPL-Run.bat file Creates RunEP.bat file and executes Displays run status (eplusout.end) Can view all input and output Files Several user options available

15

EP-Launch Access EnergyPlus documentation Select and edit input file

Select weather file

View output files Run EnergyPlus

16

EP-Launch Setup Select desired text editor program (defaults to .txt editor) Select drawing viewer for DXF files (VoloView Express is free from www.autodesk.com) Select desired spreadsheet program to view csv files 17

EP-Launch Options Open only ERR and EIO output files Pause batch file after EnergyPlus execution to read traceback if crash

Wide format for long path names

18

EP-Launch Alternate Layout

19

Results ERR file contains warnings and errors

(always look here!) EIO file contains additional EnergyPlus results, including verification of location, environment, summary reports, etc. View menu – ERR/EIO only (F2) RDD file lists the output variables available from the run 20

Results (cont’d)  ESO file contains the raw output from the run

(users rarely look here)  CSV versions of ESO and MTR files can be opened by clicking on the “Spreadsheet” button 

Can be imported into any spreadsheet program that accepts the CSV format

 DXF file can be viewed by clicking on the

“Drawing File” button 

Can be imported into any CAD program that accepts the DXF format 21

IDF Editor  Not really an “interface”  Reads IDD  Structures data entry based on IDD  Writes objects in IDD order 



e.g. Run Period, Design Days, all Materials, all Constructions, all Zones, all Surfaces Files generated by other means will be rearranged

 CANNOT read IMF files (see EP-Macro) 22

IDF Editor

Select object type from class list Description of entry, max and min when applicable Pull-down list of keywords or references when applicable Objects shown here for selected class 23

WinEPDraw Creates dxf drawing Does not run simulation *.epderr file reports errors Run independently EP-Launch drawing button will run if 

dxf file not present



dxf file older than idf 24

Summary EnergyPlus install includes

documentation and example files Various auxiliary programs can be used with EnergyPlus when a more sophisticated interface is not available, the most important utilities are: 

EP-Launch (launches EnergyPlus)



IDF Editor (edits input files for EnergyPlus) 25

Lecture 2: Simulating Buildings and EnergyPlus Auxiliary Programs


Importance of this Lecture to the Simulation of Buildings  Simulation of buildings requires 3 main steps:  Creation of Building Model (Input Definition)  Utilizing a Simulation Program (Running/Debugging Input)  Analysis of Simulation Results (Output)  Most of the lectures in this course focus on the first

of the three steps since this is where most of your time will be spent  However, using a program and understanding its output is as critical to the proper use of simulation  This lecture focuses on the last two steps since they will be useful throughout the semester and will restrict the discussion to the program we are using this semester: EnergyPlus 2

Purpose of this Lecture Gain an understanding of the following

EnergyPlus related issues 

Simulation Types



EnergyPlus Files



Auxiliary Programs



EnergyPlus Output



Handling Errors in Input

3

Simulation Types  Peak Thermal Load Calculation  Simulation run for an extreme (design) day or several design days  Generally used for determining sizing of equipment such as fans, chillers, boilers, etc.  Building Energy Analysis  Simulation run for an extended period of time: a month, season, year, or several years using weather files  Includes the building response to the entire range of conditions expected at a particular site  Helps evaluate the energy cost of the building over longer periods of time

4

EnergyPlus Files  Let EP-Launch or RunEPlus.bat worry about

getting files into the right place  Simple, console app concept    

Energy+.idd – constant Energy+.ini – working file paths In.idf – input data file In.epw – weather data

 Input files in working directory  Execution “from” working directory 5

Files Overview Simple ASCII files Simple input format (self-contained) User-defined output (comma separated

data) can be interpreted by many programs   

Spreadsheets Databases Custom Programs

Note: be advised that the use of some word processing programs to create input files may result in errors due to their use of non-simple carriage returns. 6 Notepad works well if one is trying to create input files “by hand”.

EP-Launch Assistance in running EnergyPlus Reads EPL-Run.bat file Creates RunEP.bat file and executes Displays run status (eplusout.end) Can view all input and output files Several user options available

7

EP-Launch Access EnergyPlus documentation Select and edit input file

Select weather file

View output files Run EnergyPlus

8

EP-Launch Setup Select desired text editor program (defaults to .txt editor) Select drawing viewer for DXF files (VoloView Express is free from www.autodesk.com) Select desired spreadsheet program to view csv files 9

EP-Launch Options Open only ERR and EIO output files Pause batch file after EnergyPlus execution to read traceback if crash

Wide format for long path names

10

EP-Launch Alternate Layout

11

IDF Editor  Not really an “interface”  Reads IDD  Structures data entry based on IDD  Writes objects in IDD order  e.g. Run Period, Design Days, all Materials, all Constructions, all Zones, all Surfaces  Files generated by other means will be rearranged  CANNOT read IMF files (see EP-Macro)  Some tasks must be done in text editor 12

IDF Editor

Select object type from class list Description of entry, max and min when applicable Pull-down list of keywords or references when applicable Objects shown here for selected class 13

WinEPDraw Creates dxf drawing Does not run simulation *.epderr file reports errors Run independently EP-Launch drawing button will run if 

dxf file not present



dxf file older than idf 14

Results ERR file contains warnings and errors

(always look here!) EIO file contains additional EnergyPlus results, including verification of location, environment, summary reports, etc. View menu – ERR/EIO/BND only (F2) RDD file lists the output variables available from the run 15

Results (cont’d)  ESO file contains the raw output from the run

(users rarely look here)  CSV versions of ESO and MTR files can be opened by clicking on the “Spreadsheet” button 

Can be imported into any spreadsheet program that accepts the CSV format

 DXF file can be viewed by clicking on the

“Drawing File” button 

Can be imported into any CAD program that accepts the DXF format 16

Input Error Detection  Input Processor checks field type, max, min,

required fields, based on IDD specifications  Inputs are not processed sequentially  Simulation modules perform additional checks  Certain errors will terminate program before all input has been retrieved by simulation modules  Previously undetected errors may be reported after fixing other errors 17

Error Diagnostics ERR file reports any errors that may

have occurred during the simulation 



Error messages may be generated during its input phase or during the simulation Error messages usually identify specific object type and name related to the error – Use search command to locate error in IDF file 18

Error Diagnostics (cont’d) Four levels of error severity: 

Message – Informative. No action required.



Warning – Take note. Fix as applicable.



Severe – Should fix. Program may abort.



Fatal – Program will abort

19

Error Diagnostics (cont’d) Running EnergyPlus with CVBbRh.idf

results in the following Err file:

Program Version,EnergyPlus, Version 1.1.1 ** Warning ** Version in IDF="1.1" not the same as expected="1.1.1" ** Warning ** World Coordinate System selected. Some Zone Origins are non-zero. ** ~~~ ** These will be used in Daylighting:Detailed calculations but not in normal geometry inputs. ************* Testing Individual Branch Integrity ************* All Branches passed integrity testing ************* Testing Individual Supply Air Path Integrity ************* All Supply Air Paths passed integrity testing ************* Testing Individual Return Air Path Integrity ************* All Return Air Paths passed integrity testing ************* No node connection errors were found. ** Warning ** The following lines are "Orphan Objects". These objects are in the idf ** ~~~ ** file but are never obtained by the simulation and therefore are NOT used. ** ~~~ ** See InputOutputReference document for more details. ************* Object=FLUIDNAMES=WATER ************* Object=FLUIDPROPERTYTEMPERATURES=GLYCOLTEMPERATURES ************* Object=FLUIDPROPERTYCONCENTRATION=WATER ************* EnergyPlus Completed Successfully-- 3 Warning; 0 Severe Errors; Elapsed Time=00hr 00min 06sec

Only messages and warnings—EnergyPlus ran successfully 20

Error Diagnostics (cont’d) Typo in file BUILDING, NONE, !- Building Name 0.0000000E+00, !- North Axis {deg} Suburbs, !- Terrain 3.9999999E-02, !- Loads Convergence Tolerance Value {W} 0.4000000, !- Temperature Convergence Tolerance Value {deltaC} FullInteriorAndExterior; !- Solar Distribution abcdefg

Typo here

SOLUTION ALGORITHM, CTF; !- SolutionAlgo

21

Error Diagnostics (cont’d) Err file error message Program Version,EnergyPlus 1.1.0.018, 4/23/2003 9:40 AM ************* IDF Line=28 abcdefg ** Severe ** , or ; expected on this line

22

Error Diagnostics (cont’d) *.audit file for context Search for error flag 20

BUILDING, 21 NONE, !- Building Name 22 0.0000000E+00, !- North Axis {deg} 23 Suburbs, !- Terrain 24 3.9999999E-02, !- Loads Convergence Tolerance Value {W} 25 0.4000000, !- Temperature Convergence Tolerance Value {deltaC} 26 FullInteriorAndExterior; !- Solar Distribution 27 Typo here 28 abcdefg ** Severe ** , or ; expected on this line 29

Error message here

23

Error Diagnostics (cont’d) Crashes  



EP-Launch indicates that EnergyPlus crashed EP-Launch→View Menu→Pause During Simulation - adds a pause to view traceback Name of failed routine may provide a clue to where the problem lies, e.g., CalcSimple Cooling Coil

24

Error Diagnostics (cont’d)

25

Error Diagnostics (cont’d)  Reports  Report, Surfaces, DXF  DXF file that will render the surfaces specified in the IDF

file into something viewable



Report, Surfaces, Details  Lists all surfaces with area, azimuth, tilt, construction

and surface type



Report Variable Dictionary  Allows determination of all of the key strings to specify

report variables in the input files (produces RDD file)



Report, Construction  Lists thermal properties of all construction types 26

Error Diagnostics (cont’d) Common Errors 

Missing comma or semicolon



Inappropriate zero value



Upside down roof or floor



HVAC missing components



HVAC misconnected nodes



Empty objects in IDF Editor 27

Summary  Two main simulation categories:  

Thermal load calculations Energy analysis

 Important input files for EnergyPlus:  

Energy+.idd and Energy+.ini In.idf and in.epw

 EP-Launch used to select input files and

weather as well as executing EnergyPlus 28

Summary (cont’d)  Output and error diagnostics: 



 

*.err (and *.audit) messages are not necessarily problems Messages and warnings may or may not be important to the simulation (informational in many cases) Severe and fatal errors need to be addressed Other output files (*.eso, *.csv, *.dxf, *.eio) can also aid in determining problems in user input

29

Lecture 3: Output—Reports, Variables, and Meters


Importance of this Lecture to the Simulation of Buildings Running a simulation program results in

the production of output data Understanding the output data and its format can help avoid mistakes and save time

2

Purpose of this Lecture Gain an understanding of:  



Different output files of EnergyPlus Which output will be the most useful and how to get it Define accumulation “meters” to save time in processing and analyzing results

3

Keywords Covered in this Lecture Report Report Variable Report Meter

4

Output Data Format Same philosophy as for input;

somewhat human readable output files EnergyPlus can perform some output processing to help limit output size User definable variable level reporting

5

Output Reporting Flexibility User can select any variables available

for output User can specify output at time step, hourly, daily, monthly, or environment intervals User can schedule each output variable User can select various meters by resource and end-use 6

Types of Output Report Variables Report Meters Default Reports Optional Reports

7

Output Files  Eplusout.  Filename.  eio

Initialization Output – environments, constructions, global settings

 eso

Standard Output – numeric data

 csv

csv spreadsheet of eso data

 err

Errors Output – always review this!

 rdd

Report Data Dictionary – list of valid report variables for a particular run 8

Output Files (cont’d)  dxf

dxf drawing of building surfaces  mtr Meter output – numeric data  Meter.csv csv spreadsheet of meter data  mtd Meter details – lists which report variables are on which meters  cif Comis input file  zsz Zone sizing report  ssz System sizing report Created using CVBbR h.idf 9

Output Files (cont’d) bnd

Branch and node details dbg Debug output trn Trnsys output sln Vertices of surface For more details see Output Details and Examples 10

Report Commands Report Variable, EAST ZONE, Mean Air Temperature, Timestep;

MAT only for EAST ZONE every timestep

Report Variable, *, Mean Air Temperature, Daily, Report Schedule;

MAT for all zones, daily average, only when “Report Schedule” equals 1

Report, Variable Dictionary;

List all available variables *.rdd

Report, Construction;

List material and construction properties *.eio Produce drawing of surfaces *.dxf List all surfaces with area, tilt, construction, etc.

Report, Surfaces, DXF; Report, Surfaces, Details;

11

Report Commands (cont’d) Report Variable,,Outdoor Dry Bulb,monthly; Report Variable,Zone 1,Zone/Sys Sensible Cooling Energy,monthly; Report Variable,Zone 1,Zone/Sys Sensible Heating Energy,monthly; Report Variable,,Heating Coil Energy,monthly; Report Variable,,DX Coil Sensible Cooling Energy,monthly; Report Variable,,DX Coil Latent Cooling Energy,monthly; Report Variable,,DX Coil Total Cooling Energy,monthly; Report Variable,,DX Cooling Coil Electric Consumption,monthly; Report Variable,,Fan Electric Consumption,monthly; Report Variable,,Zone/Sys Air Temp,monthly; Report,Variable dictionary; Report,surfaces,dxf; Report,surfaces,details; Report,construction;

12

Output Data Dictionary (ESO File) Data Dictionary - Beginning of Output Data File 1,5,Environment Title[],Latitude[degrees],Longitude[degrees],Time Zone[],Elevation[m] 2,6,Day of Simulation[],Month[],Day of Month[],DST Indicator[1=yes 0=no],Hour[],StartMinute[],EndMinute[],DayType 3,3,Cumulative Day of Simulation[],Month[],Day of Month[],DST Indicator[1=yes 0=no],DayType ! When Daily Report Variables Requested 246,2,ZN001:FLR001,Surface Inside Temperature[C] !TimeStep 302,2,ZN002:FLR001,Surface Inside Temperature[C] !TimeStep . . . End of Data Dictionary

13

Output Data (ESO File) Output Data – After the Data Dictionary 1,CHANUTE AFB ILLINOIS SUMMER, 40.30, -88.13, 229.51 2, 1, 7,21, 0, 1, 0.00,10.00,Monday 246,33.3319029536235 302,31.7565160760406 . . .

-6.00,

14

ESO vs. CSV  ESO  “Raw” data in comma separated format  “Stream of conscience” report—variables print as they are determined  Less convenient for viewing variables  CSV  Organized data in comma separated format  Each row contains data in columns for a particular time step  More convenient for viewing variables  Requires an .rvi file and must run post-processing program  EP-Launch handles this automatically

15

CSV File Sample Date/Time Environment:Outdoor ZONE ONE:Zone/Sys Sensible ZONE ONE:Zone/Sys Sensible ZONE ONE:Zone/Sys Air Dry Bulb [C](Monthly) Heating Energy[J](Monthly) Cooling Energy[J](Monthly) Temp[C](Monthly) July 25.58495468 0.00E+00 19028775.23 24.4112152 January -17.77778 253868837.1 0.00E+00 20.28659003 January -4.63546707 4144370093 0.00E+00 20.43495965 February -2.23312872 3151142586 0.00E+00 20.46221742 March 1.603242608 2545318797 0.00E+00 20.54348182 April 8.370677083 1431785319 324853.0522 21.20071107 May 15.30398185 639305402.1 51404202.22 22.43806808 June 21.09550347 164326207.4 145308752.2 23.40095162 July 23.49973118 65628804.19 244539864.1 23.81873695 August 21.75707325 96943677.86 103740404 23.32673507 September 18.11458333 346023544.8 45088296.07 22.40959675 October 11.73642473 1065565115 714539.5928 21.18788477 November 4.232118056 2260965068 0.00E+00 20.49516327 December -2.566599462 3853388966 0.00E+00 20.46126771

16

CSV File Sample (cont’d) Part of the CSV file created when the

CVBbRh.idf file is run in EnergyPlus:

RESISTIVE ZONE:Mean Air Temperatur e[C](Hourly: REPORTSC Date/Time H) 07/21 01:00 32.35558 07/21 02:00 31.81557 07/21 03:00 31.31389 07/21 04:00 30.84865 07/21 05:00 30.42387 07/21 06:00 30.03226 07/21 07:00 29.80721 07/21 08:00 24.12819 07/21 09:00 24.00079 07/21 10:00 24.0007 07/21 11:00 23.99996 07/21 12:00 24.00028 07/21 13:00 23.99991 07/21 14:00 23.99956 07/21 15:00 23.99998 07/21 16:00 24.00017 07/21 17:00 24.00003 07/21 18:00 38.04053 07/21 19:00 36.46327 07/21 20:00 35.54667 07/21 21:00 35.21486 07/21 22:00 34.56882 07/21 23:00 33.78711 07/21 24:00 33.00431

EAST ZONE:Mean Air Temperatur e[C](Hourly: REPORTSC H) 31.84687 31.36997 30.93895 30.52358 30.11834 29.72461 29.84088 24.20936 23.99989 24.0003 24.00012 24.00011 23.99997 24.01824 24.1879 24.35251 24.33324 35.66377 34.70622 33.74085 33.5262 33.18677 32.78502 32.36126

NORTH ZONE:Mean Air Temperatur e[C](Hourly: REPORTSC H) 32.54195 31.94508 31.42794 30.96918 30.52752 30.09109 29.9142 24.22478 23.99957 23.99982 24.00022 24.00003 24.00001 24.0001 24.0387 24.24059 24.34564 35.93962 35.23245 34.69495 34.64345 34.26335 33.74649 33.17585

RESISTIVE ZONE:Zone /Sys Sensible Cooling Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 7969336 1.45E+07 1.51E+07 1.61E+07 1.72E+07 1.81E+07 1.92E+07 1.99E+07 2.03E+07 2.03E+07 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

EAST ZONE:Zone /Sys Sensible Cooling Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.02E+07 1.33E+07 1.39E+07 1.48E+07 1.56E+07 1.62E+07 1.71E+07 1.73E+07 1.75E+07 1.75E+07 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

NORTH ZONE:Zone /Sys Sensible Cooling Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.20E+07 1.83E+07 1.89E+07 1.96E+07 2.04E+07 2.07E+07 2.17E+07 2.23E+07 2.26E+07 2.29E+07 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

RESISTIVE ZONE:Zone /Sys Sensible Heating Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

EAST ZONE:Zone /Sys Sensible Heating Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

NORTH ZONE:Zone /Sys Sensible Heating Energy[J](H ourly:REPO RTSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

ZONE1BAS EBOARD:B aseboard Heating Rate[W](Ho urly:REPOR TSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4065.72 2190.512 1987.641 1708.771 1389.911 1196.966 879.5861 656.8229 516.8994 523.1177 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

ZONE2BAS EBOARD:B aseboard Heating Rate[W](Ho urly:REPOR TSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2024.82 1066.101 869.9992 635.6866 390.1691 270.4863 35.07354 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

ZONE3BAS EBOARD:B aseboard Heating Rate[W](Ho urly:REPOR TSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2997.335 1132.316 944.2528 732.0659 516.0278 460.9324 196.6353 14.17869 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

DETAILED COOLING COIL:Total Water Cooling Coil Rate[W](Ho urly:REPOR TSCH) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 19442.14 18783.6 18799.07 18802.23 18803.26 18783.9 18781.08 18849.89 18973.62 19013.39 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

17

RVI File RVI: Report Variable Input List of variables to take from ESO file

and report to CSV file Example: eplusout.eso eplusout.csv Outdoor Dry Bulb Zone/Sys Air Temp Zone/Sys Sensible Cooling Energy Zone/Sys Sensible Heating Energy FangerPMV PierceTSENS KsuTSV 0

Input file name for post-processor Output file name for post-processor

Report Variables (see IDF or RDD file) to be taken from ESO file and reported in CSV file End of file marker

18

Report Data Dictionary (RDD Files) Lists applicable output variables for a

given input file Must activate with “report, variable dictionary;” command Var Type,Var Report Type,Variable Name [Units] Zone,Average,Outdoor Dry Bulb [C] Zone,Average,Outdoor Barometric Pressure [Pa] Zone,Average,Mean Air Temperature[C] HVAC,Sum,Zone/Sys Sensible Heating Energy[J] HVAC,Average,Zone/Sys Sensible Heating Rate[W]

19

Meters  Accumulate multiple outputs of same form  Appropriate variables are grouped onto “meters” for

reporting purposes  May ease analysis of output  Values are put onto the eplusout.mtr file  Meter component details in eplusout.mtd file  Meter names applicable for the simulation are shown on the Report Data Dictionary file  Meter names are of two forms:  

: :: 20

Meters – Resource Types  Electricity

 Propane

 Gas

 Water

 Gasoline

 Steam

 Diesel

 PurchasedCooling

 Coal

 PurchasedHeating

 FuelOil#1

 EnergyTransfer (coil

 FuelOil#2

& equipment loads)

21

Meters – End Use Types  GeneralLights

 Heating

 TaskLights

 Cooling

 ExteriorLights  ZoneSource  ExteriorEquipment  Fans  Pumps

 HeatRejection  Humidifier  HeatRecovery  DHW  Cogeneration  Miscellaneous 22

Meters – Meter Types Facility (Master Meters) Submeters: 

Zone (lights, plug loads, etc.)



Building (all zones combined plus exterior)



System (air handlers, terminal units)



Plant (chillers, boilers, DHW, etc.)

23

Meters – Meter Types Elec:Zone

Lights:Zone

Zone

Elec:HVAC

Air loop Gas:HVAC Plant Loop

Building System

Elec:Plant

Gas:Plant

24

Input for Meters Report Meter, Electricity:*, Hourly;

All electric meters, for all end uses and all levels

Report Meter, Electricity: Facility, monthly;

Master electric meter

Report Meter, Cooling: Electricity, monthly;

Cooling equipment

25

Input for Meters (cont’d) Report Report Report Report Report Report Report Report

Meter,Fans:Electricity,monthly; Meter,Cooling:Electricity,monthly; Meter,Heating:Electricity,monthly; Meter,Electricity:HVAC,monthly; Meter,Electricity:Facility,monthly; Meter,Heating:Gas,monthly; Meter,Gas:HVAC,monthly; Meter,Gas:Facility,monthly;

26

Meter Details File Lists exactly what is included in each

meter *.mtd output file

For Meter=Electricity:Plant [J], contents are: LITTLE CHILLER:Chiller Electric Consumption [J] BIG CHILLER:Chiller Electric Consumption [J] CIRC PUMP:Pump Electric Consumption [J] COND CIRC PUMP:Pump Electric Consumption [J] HW CIRC PUMP:Pump Electric Consumption [J] BIG TOWER:Tower Fan Electric Consumption [J] 27

Output Files Summary Simple ASCII files Simple input format (self-contained) User-defined output can be interpreted

by many programs 

Spreadsheets



Databases



Custom Programs 28

Summary  ESO (EnergyPlus Standard Output) file

provides user with “raw” output data from EnergyPlus run

 CSV file is a version of the ESO file that is in a

format more readily usable in a spreadsheet program

 Meters and meter output are convenient ways

of grouping data for output analysis

29

Lecture 4: Simulation Control, Location, and Weather Input


Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways:  Location and exterior thermal environment  Construction  HVAC system  Exterior thermal environment is a driving force that

determines how a building will respond  Energy efficient design requires an understanding of and a response to the exterior thermal environment  Thermal simulation requires information on the exterior thermal environment to properly analyze the building from an energy perspective 2

Purpose of this Lecture Gain an understanding of how to control

the exterior environment of the simulation 

Building Location



Weather and Ground Temperature Data



Length of Simulation



Other General Features of the Input

3

Keywords Covered in this Lecture  Version  Run Control  Location  DesignDay  SpecialDayPeriod  RunPeriod  DaylightSavingPeriod  GroundTemperature  GroundReflectance  Snow Ground Reflectance Modifiers 4

Quick Review of Relationship Between IDD and IDF Files IDD: Input Data Dictionary  File which defines what information should be located in the user input file  This file should NOT be modified IDF: Input Data File  User input file containing information about the building and its primary and secondary systems  This file can be modified using a text editor or using the IDF Editor 5

Keyword: Version IDD Description VERSION, \unique-object A1 ; \field Version Identifier \required-field

Notes 



\unique-object means only one of these are allowed per IDF file \required-field means this field must be present in the description 6

Keyword Example: Version  IDF Examples Version, 1.1; ! Shortened input format Version, 1.1; !- Version Identifier

 Notes:  The Version identifier refers to a version of the EnergyPlus program  Updates in the EnergyPlus program may result in changes to the IDD  An error message will result if the IDF file version does not correspond to the version of EnergyPlus being run  This course is based on EnergyPlus Version 1.1 7

Keyword: Location IDD Description (shortened) Location, A1 , \field N1 , \field N2 , \field N3 , \field N4 ; \field

Location Name Latitude Longitude TimeZone Elevation

IDD Description (detailed) Location, Only one per IDF file \unique-object \min-fields 5 All five fields are required A1 , \field Location Name \required-field Information expected: a name \type alpha Field is a character string 8

Keyword: Location IDD Description (detailed, continued) N1 , \field Latitude Building site latitude (global position) \units deg \minimum -90.0 N1 in degrees \maximum +90.0 Limits (-90≤N1≤+90) and Default Value \default 0.0 \note + is North, - is South, degree minutes represented \note in decimal (i.e. 30 minutes is .5) Interpretation \type real Field is a decimal value information N2 , \field Longitude \units deg Building site longitude (global position) \minimum -180.0 \maximum +180.0 \default 0.0 \note - is West, + is East, degree minutes represented \note in decimal (i.e. 30 minutes is .5) 9 \type real

Keyword: Location IDD Description (detailed, continued) N3 , \field Time Zone “Political” time zone \units hr N3 in hours \minimum -12.0 \maximum +12.0 Note \default 0.0 \note Time relative to GMT. Decimal hours. \type real N4 ; \field Elevation Building site elevation \units m N4 in meters \minimum -300.0 \maximum< 6096.0 \default 0.0 \type real 10

Keyword Example: Location  IDF Example Location, DENVER, 39.750, -104.870, -7.0, 1610.26;

or

Location, DENVER COLORADO, 39.750, -104.870, -7.0, 1610.26;

 Notes: 

!!!!!-

LocationName Latitude {deg} Longitude {deg} TimeZone {hr (decimal)} Elevation {m}

Location affects the sun angles, air properties, etc. that the building experiences

11

Keyword: DesignDay IDD Description (shortened) DesignDay, A1 , \field N1 , \field N2 , \field N3 , \field N4 , \field N5 , \field N6 , \field N7 , \field N8 , \field N9 , \field N10, \field N11, \field A2 , \field N12; \field

DesignDayName Maximum Dry-Bulb Temperature Daily Temperature Range Wet-Bulb Temperature At MaxTemp Barometric Pressure Wind Speed Wind Direction Sky Clearness Rain Indicator Snow Indicator Day Of Month Month Day Type Daylight Saving Time Indicator

12

Keyword: DesignDay Purpose: the DesignDay input syntax

defines a single day of weather information Design day simulations are often used for peak load or sizing calculations Data required for this keyword can be found in a variety of places (see next slide) 13

DesignDay Sources  MacroDataSets folder  US, Canada, and International  2001 ASHRAE data  Datasets –  US locations  pre-1997 ASHRAE data, from BLAST library  *.ddy files  Included in weather data zip files on web site  2001 ASHRAE data 14

Keyword: DesignDay IDD Description (detailed) Keyword—note all one word DesignDay, \min-fields 14 14 fields (all) required A1 , \field DesignDayName \type alpha Unique character string \required-field name for design day \reference DesignDays N1 , \field Maximum Dry-Bulb Temperature Other references to \required-field a design day \units C N1 is the maximum in the IDF will \minimum> -70 dry bulb temperature expect an \maximum< 70 experience for this existing \note design day in degrees design day \type real Celsius name 15

Keyword: DesignDay IDD Description (detailed) N2 , \field Daily Temperature Range \required-field Range of temperatures expected \units deltaC \minimum 0 Units are ∆°C Must be zero or greater \type real \note must still produce appropriate maximum dry bulb N3 , \field Wet-Bulb Temperature At MaxTemp \required-field Mean coincident wet-bulb \units C temperature in °C \minimum> -70 \maximum< 70 \type real

16

Keyword: DesignDay IDD Description (detailed) N4 , \field Barometric Pressure \required-field \units Pa \minimum> 70000 \maximum< 120000 \type real \ip-units inHg N5 , \field Wind Speed \required-field \units m/s \minimum 0 \maximum 40 \ip-units miles/hr \type real

Outdoor barometric pressure (assumed constant for entire day) in Pascals IP Units if interface accepts these units Wind speed (assumed constant for entire day) in meters per second

17

Keyword: DesignDay IDD Description (detailed) N6 , \field Wind Direction Wind direction \required-field (assumed constant \units deg for entire day) in \minimum 0 degrees (assumes \maximum 359.9 North is 0, East is \note North=0.0 East=90.0 90, South is 180, \type real etc.) N7 , \field Sky Clearness \required-field Sky clearness \minimum 0.0 (assumed constant Maximum allows for \maximum 1.2 for entire day) altitude adjustment \default 0.0 \note 0.0 is totally unclear, 1.0 is totally clear \type real 18

Keyword: DesignDay IDD Description (detailed) N8 , \field Rain Indicator Rain flag (assumed \minimum 0 constant for entire \maximum 1 day) affects \default 0 exterior convection \note 1 is raining, 0 is not coefficients \type integer Rain flag (assumed N9 , \field Snow Indicator constant for entire \minimum 0 day) affects ground \maximum 1 reflectance \default 0 \note 1 is Snow on Ground, 0 is no Snow on Ground \type integer Should be an integer value not a decimal number

19

Keyword: DesignDay IDD Description (detailed)

Numerical day of N10, \field Day Of Month month (must be \required-field valid for month \minimum 1 chosen) \maximum 31 \type integer \note must be valid for Month field N11, \field Month \required-field Numerical month of \minimum 1 the year \maximum 12 \type integer

20

Keyword: DesignDay Type of day/day of the week for design  day (may affect A2 , \field Day Type schedule values) \required-field \note Day Type selects the schedules appropriate \note for this design day This field is a choice \type choice of one of the \key Sunday options listed as \key Monday \key \key Tuesday

IDD Description (detailed)

\key \key \key \key \key \key \key \key \key

Wednesday Thursday Friday Saturday Holiday SummerDesignDay WinterDesignDay CustomDay1 CustomDay2

This field must equal one of these choices of keywords (note that none of these keywords has spaces) 21

Keyword: DesignDay IDD Description (detailed) N12; \field Daylight Saving Time Indicator \minimum 0 Whether daylight \maximum 1 savings time should be \default 0 in effect for this design \note 1=Yes, 0=No day \type integer

22

Keyword Example: DesignDay IDF Example DesignDay, DENVER COLORADO SUMMER, !- DesignDayName 32.8, !- Maximum Dry-Bulb Temperature {C} 17.8, !- Daily Temperature Range {C} 15.0, !- Wet-Bulb Temperature At MaxTemp {C} 84060.0, !- Barometric Pressure {Pa} 3.97, !- Wind Speed {m/s} 146.0, !- Wind Direction {deg} 1.10, !- Sky Clearness 0, !- Rain Indicator 0, !- Snow Indicator 21, !- Day Of Month 7, !- Month Monday, !- Day Type 0; !- Daylight Saving Time Indicator

23

Keyword: DaylightSavingPeriod  IDD Description (shortened) DaylightSavingPeriod, A1, \field StartDate A2; \field EndDate

 Purpose: define the time frame during which

daylight savings rules should apply  Note that this can be specific to location (not all sites use daylight savings time in the summer)

24

Keyword: DaylightSavingPeriod IDD Description (detailed) Keyword—note all one word DaylightSavingPeriod, \unique-object \min-fields 2 \memo This object sets up the daylight saving period \memo for any RunPeriod. \memo Ignores any daylightsavingperiod values on the \memo weather file and uses this definition. \memo (These are not used with DesignDay objects.) A1, \field StartDate Note: not used for design \required-field days and will override any information found on the Date when daylight weather file savings goes into effect (details on format on next slide) 25

Keyword: DaylightSavingPeriod IDD Description (detailed) Date when daylight A2; \field EndDate savings period ends \required-field \memo Dates can be several formats: \memo / (month/day) Format information \memo for start and end date \memo of daylight savings \memo in in below) \memo can be January, February, March, etc. \memo Months can be the first 3 letters of the month \memo can be Sunday, Monday, Tuesday, etc. \memo can be 1 or 1st, 2 or 2nd, etc. up to 5(?) Date examples: 4/11 OR 11 April OR April 11 1st Sunday in April OR 1 Sunday in Apr Last Sunday in October

26

Keyword Example: DaylightSavingPeriod IDF Examples DaylightSavingPeriod, 1st Sunday in April, !- Start Date Last Sunday in October; !- End Date

or DaylightSavingPeriod, 4/1, !- Start Date 31 October; !- End Date

27

Keyword: SpecialDayPeriod  IDD Description (shortened) SpecialDayPeriod, A1, \field Holiday Name A2, \field StartDate N1, \field duration (number of days) A3; \field SpecialDayType

 Purpose: to set up the occurrence of special

days throughout the year or to override the values set in a weather file

 Note: this information does not apply to

design days

28

Keyword: SpecialDayPeriod IDD Description (detailed) SpecialDayPeriod, Keyword—note all one word \min-fields 4 \memo This object sets up holidays/special days to be \memo used during weather file run periods. \memo (These are not used with DesignDay objects.) \memo Depending on the value in the run period, days \memo on the weather file may also be used. However, \memo the weather file specification will take \memo precedence over any specification shown here. \memo (No error message on duplicate days or \memo overlapping days). Unique identifying name A1, \field Holiday Name \required-field 29

Keyword: SpecialDayPeriod IDD Description (detailed)

A2, \field StartDate Date when period \required-field starts; format \memo Dates can be several formats: similar to dates for \memo / (month/day) daylight savings \memo time \memo \memo in in \memo can be January, February, March, etc. \memo Months can be the first 3 letters of the month \memo can be Sunday, Monday, Tuesday, etc. \memo can be 1 or 1st, 2 or 2nd, etc. up to 5(?) N1, \field duration (number of days) \minimum 1 Length of special \maximum 366 30 period in days \default 1

Keyword: SpecialDayPeriod IDD Description (detailed) A3; \field SpecialDayType \required-field \note SpecialDayType selects the schedules \note appropriate for each day so labeled \type choice \key Holiday Note the \key SummerDesignDay impact on \key WinterDesignDay schedules \key CustomDay1 \key CustomDay2 \default Holiday

Type of day (see choices given in the \key list) this should be considered

31

Keyword Example: SpecialDayPeriod IDF Example SpecialDayPeriod, Memorial Day, Last Monday in May, 1, Holiday;

!!!!-

Holiday Name Start Date duration (number of days) SpecialDayType

32

Keyword: RunPeriod  IDD Description (shortened) RunPeriod, N1 , \field N2 , \field N3 , \field N4 , \field A1 , \field A2, \field A3, \field A4, \field A5, \field A6; \field

Begin Month Begin Day Of Month End Month End Day Of Month Day Of Week For Start Day Use WeatherFile Holidays/Special Days Use WeatherFile DaylightSavingPeriod Apply Weekend Holiday Rule Use WeatherFile Rain Indicators Use WeatherFile Snow Indicators

 Purpose: to define the simulation period for

EnergyPlus (program does not assume entire year simulation) 33

Keyword: RunPeriod IDD Description (detailed) Keyword—note all one word RunPeriod, \min-fields 10 N1 , \field Begin Month \required-field \minimum 1 Starting date for period \maximum 12 to be simulated; \type integer entered as two separate N2 , \field Begin Day Of Month fields, both integer \required-field values \minimum 1 \maximum 31 \type integer

34

Keyword: RunPeriod IDD Description (detailed, continued) N3 , \field End Month \required-field \minimum 1 \maximum 12 \type integer N4 , \field End Day Of Month \required-field \minimum 1 \maximum 31 \type integer

Ending date for period to be simulated; entered as two separate fields, both integer values

35

Keyword: RunPeriod IDD Description (detailed, continued) A1 , \field Day Of Week For Start Day \note = \default UseWeatherFile Day of week for starting Note that \type choice date; can be used to this is not a \key Sunday override day of week “required” \key Monday specified on the weather file field due to \key Tuesday the lack of \key Wednesday the line that \key Thursday Options for day of week says \key Friday for starting date “\required\key Saturday field”; all \key UseWeatherFile fields after this point are also optional

36

Keyword: RunPeriod IDD Description (detailed, continued) A2,

A3,

\field Use WeatherFile Holidays/Special Days \note If yes or blank, use holidays on Weatherfile. \note If no, do not use the holidays on Weatherfile. \note Note: You can still specify holidays/special days \note using the SpecialDayPeriod object(s). \type choice These two input fields are used to override the \default Yes definition of holidays and daylight savings time \key Yes period from the weather file. \key No \field Use WeatherFile DaylightSavingPeriod \note If yes or blank, use period specified on Weatherfile. \note If no, do not use period as specified on Weatherfile. \type choice \default Yes The choices for these fields are \key Yes simply a “yes” or a “no”. 37 \key No

Keyword: RunPeriod IDD Description (detailed, continued) A4,

A5,

A6;

\field Apply Weekend Holiday Rule \note if yes and single day holiday falls on weekend, \note "holiday" occurs on following Monday \type choice These three input \key Yes fields are used to \key No override the \default No \field Use WeatherFile Rain Indicators definition of holiday \type choice weekend rules, \key Yes presence of rain \key No indicators, and \default Yes presence of snow \field Use WeatherFile Snow Indicators indicators from the \type choice weather file. \key Yes \key No \default Yes The choices for these fields are

simply a “yes” or a “no”.

38

Keyword Example: RunPeriod IDF Example RunPeriod, 1, 1, 3, 31;

!!!!-

Begin Month Begin Day Of Month End Month End Day Of Month

or RunPeriod, 1, 1, 3, 31, Tuesday, Yes, Yes,

!- Begin Month !- Begin Day Of Month !- End Month !- End Day Of Month !- Day of Week for Start Day Yes, Yes, Yes; !- Special Weather File Flags 39

Keyword: Run Control IDD Description (shortened) RUN CONTROL, A1, \field A2, \field A3, \field A4, \field A5; \field

Do Do Do Do Do

the the the the the

zone sizing calculation system sizing calculation plant sizing calculation design day simulations weather file simulation

Purpose: overall control of what the

user wants EnergyPlus to simulate (design days and/or weather file runs, perform auto-sizing) 40

Keyword: Run Control IDD Description (detailed) RUN CONTROL, \unique-object A1, \field Do the zone sizing calculation \type choice \key Yes \key No \default No A2, \field Do the system sizing calculation \type choice \key Yes \key No \default No A3, \field Do the plant sizing calculation \type choice \key Yes \key No \default No

Keyword— note that there IS a space between the two words

These will be discussed later in the semester

41

Keyword: Run Control IDD Description (detailed, continued) A4, \field Do the design day simulations \type choice Choices for both fields are \key Yes simply “yes” or “no” \key No \default Yes A5; \field Do the weather file simulation \type choice Fields define whether or not to \key Yes simulate design days (defined by the \key No DesignDay input line) or an attached \default Yes weather file (see RunPeriod input line)

42

Keyword Example: Run Control IDF Example RUN CONTROL, No, No, No, No, Yes;

or RUN CONTROL, No, !No, !No, !No, !Yes; !-

Do Do Do Do Do

the the the the the

zone sizing calculation system sizing calculation plant sizing calculation design day simulations weather file simulation

43

Keyword: GroundTemperatures  IDD Description (shortened) GroundTemperatures, N1 , \field January Ground Temperature N2 , \field February Ground Temperature N3 , \field March Ground Temperature . . . etc . . . N12; \field December Ground Temperature

 Purpose: to set the ground temperatures

experienced at the building location (impact on places where the ground is in contact with the building) 44

Keyword: GroundTemperatures IDD Description (detailed) GroundTemperatures, Keyword—note all one word \unique-object 12 values, one per month \min-fields 12 N1 , \field January Ground Temperature Repeated for \required-field each month of \units C the year \type real \default 13 Temperatures in Celsius; note that these are temperatures at the outside surface not “deep ground” temperatures 45

Keyword Example: GroundTemperatures IDF Example

GroundTemperatures, 20.03, 20.03, 20.13, 20.30, 20.43, 20.52, 20.62, 20.77, 20.78, 20.55, 20.44, 20.20; or GroundTemperatures, 20.03, !- January Ground Temperature {C} 20.03, !- February Ground Temperature {C} 20.13, !- March Ground Temperature {C} 20.30, !- April Ground Temperature {C} 20.43, !- May Ground Temperature {C} 20.52, !- June Ground Temperature {C} 20.62, !- July Ground Temperature {C} 20.77, !- August Ground Temperature {C} 20.78, !- September Ground Temperature {C} 20.55, !- October Ground Temperature {C} 20.44, !- November Ground Temperature {C} 20.20; !- December Ground Temperature {C}

46

Keyword: GroundReflectances IDD Description (shortened) GroundReflectances, N1 , \field January Ground Reflectance N2 , \field February Ground Reflectance N3 , \field March Ground Reflectance . . . etc . . . N12; \field December Ground Reflectance

Purpose: to set the reflectance of the

ground surrounding the building (affects radiation incident on building surfaces) 47

Keyword: GroundReflectances IDD Description (detailed) GroundReflectances, Keyword—note all one word \unique-object 12 values, one per month \min-fields 12 N1 , \field January Ground Reflectance \default 0.2 Repeated for \type real each month of \minimum 0.0 the year \maximum 1.0 \units dimensionless Note: values for reflectance are highly dependent on the type of ground cover around the building—grass, dirt, concrete, asphalt, etc.

48

Keyword Example: GroundReflectances IDF Example

GroundReflectances, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2; or GroundReflectances, 0.2, !- January Ground Reflectance 0.2, !- February Ground Reflectance 0.2, !- March Ground Reflectance 0.2, !- April Ground Reflectance 0.2, !- May Ground Reflectance 0.2, !- June Ground Reflectance 0.2, !- July Ground Reflectance 0.2, !- August Ground Reflectance 0.2, !- September Ground Reflectance 0.2, !- October Ground Reflectance 0.2, !- November Ground Reflectance 0.2; !- December Ground Reflectance

49

Keyword: Snow Ground Reflectance Modifiers  IDD Description (shortened) Snow Ground Reflectance Modifiers, N1, \field Ground Reflected Solar Modifier \minimum 0.0 \default 1.0 N2; \field Daylighting Ground Reflected Solar Modifier \minimum 0.0 \default 1.0

 Purpose: to account for the presence of snow

and how that impacts the ground reflectance (weather files will indicate whether or not there is snow on the ground)

50

Keyword: Snow Ground Reflectance Modifiers IDD Description (detailed) Snow Ground Reflectance Modifiers, N1, \field Ground Reflected Solar Modifier \minimum 0.0 \default 1.0 \note Value for modifying the "normal" ground reflectance \note when Snow is on ground when calculating the \note "Ground Reflected Solar Radiation Value“ a value of \note 1.0 here uses the "normal" ground reflectance \note Ground Reflected Solar = (BeamSolar*CosSunZenith \note + DiffuseSolar)*GroundReflectance \note This would be further modified by the Snow Ground \note Reflectance Modifier when Snow was on the ground \note When Snow on ground, effective GroundReflectance is \note GroundReflectance*"Ground Reflectance Snow Modifier" \note Ground Reflectance achieved in this manner will be 51 \note restricted to [0.0,1.0]

Keyword: Snow Ground Reflectance Modifiers IDD Description (detailed) N2; \field Daylighting Ground Reflected Solar Modifier \minimum 0.0 \default 1.0 \note Value for modifying the "normal“ daylighting \note ground reflectance when Snow is on ground \note When calculating the "Ground Reflected Solar \note Radiation Value“ a value of 1.0 here uses the \note “normal” ground reflectance \note Ground Reflected Solar = (BeamSolar*CosSunZenith \note + DiffuseSolar)*GroundReflectance \note This would be further modified by the Snow Ground \note Reflectance Modifier when Snow was on the ground \note When Snow on ground, effective GroundReflectance is \note GroundReflectance*"Ground Reflectance Snow Modifier" \note Ground Reflectance achieved in this manner will be 52 \note restricted to [0.0,1.0]

Keyword Example: Snow Ground Reflectance Modifiers IDF Example Snow Ground Reflectance Modifiers, 1.5, 2.0;

or

Snow Ground Reflectance Modifiers, 1.5, !- Ground Reflected Solar Modifier 2.0; !- Daylighting Ground Reflected Solar Modifier

53

Summary  Location and exterior thermal environment

play a critical role in determine the thermal loads/energy consumption of a building  Many input keywords in EnergyPlus control what is being simulated 

For example: Version, Run Control, Location, DesignDay, SpecialDayPeriod, RunPeriod, DaylightSavingPeriod, GroundTemperature, GroundReflectance, Snow Ground Reflectance Modifiers

 EnergyPlus flexibility also results in user

responsibility (having to define various parameters in the input file)

54

Lecture 5: Building Envelope Description (Part I)


Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways:  Location/exterior environment  Construction/building envelope  HVAC system  Building envelope/construction determines how a

building will respond to the exterior environment  Thermal simulation requires information about the physical make-up of the building, where various constructions are located and how they are oriented, how the building is subdivided into zones, etc.  Thermal simulation requires information on the building envelope to properly analyze the building from an energy perspective 2

Purpose of this Lecture Gain an understanding of how to

specify the building construction 





Groups of Surfaces (Zones) and Overall Building Characteristics Walls, Roofs, Ceilings, Floors, Partitions, etc. Materials and Groups of Materials (Constructions) 3

Keywords Covered in this and next Lecture Building Zone SurfaceGeometry Surface (all types) Construction Material:Regular Material:Regular-R Material:Air 4

Definitions and Connections  Building:  Entire collection of interior and exterior features of the structure  Buildings may consist of one or more zones  Zones:  Group of surfaces that can interact with each other thermally and have a common air mass at roughly the same temperature  One or more rooms within a building  Zones may consist of one or more surfaces 5

Definitions and Connections (cont’d)  Surfaces:  Walls, Roofs, Ceilings, Floors, Partitions, Windows, Shading Devices  One or more surfaces make up a zone  Surfaces consist of a series of materials called a “construction”  Construction:  Group of homogeneous one-dimensional material layers  Each surface must have a single construction definition  Each construction is made up of one or more materials

6

Definitions and Connections (continued) Materials: 



Define the thermal properties for layers that are used to put together a construction One or more material layers make a construction

7

Envelope Hierarchy Building

Surface

Zone

Zone

Zone

Surface

Surface

Surface

Material

… more surfaces

only one construction per surface

Construction Material

… more zones

Material

Material

… more materials 8

More on Zones Thermal zone definition very generic

and does not answer the following questions:  

How many surfaces to a zone? How many zones should be defined for a particular building?



Should each room be a zone?



Can the entire building be a zone? 9

Defining Thermal Zones by Objective Objectives of a study can dictate the

size and number of thermal zones 

Air flow study: sizing fans and ducts  Several rooms per zone  Zone per system type



“Block loads” or central plant study: sizing of heating and cooling producers  Minimize number of zones (maybe only 1) 10

Ft. Monmouth Education Center

11

Defining Thermal Zones by Design Conditions “∆T” test: if there is an air temperature

difference between adjacent spaces, separate thermal zones are needed 

Might also be seen in different control types

12

Defining Thermal Zones by Design Conditions (cont’d) Space usage/internal gains test: 

Differences in internal gains may result in different conditioning requirements or distribution  Office vs. gymnasium



Space usage differences may alter the ventilation or exhaust requirements of a space  Office vs. kitchen vs. chemistry laboratory 13

Defining Thermal Zones by Design Conditions (cont’d) Environmental conditions test: exposure

to different thermal surroundings/quantifying the effect 

Different space orientations—solar gains



Exposure to the ground



Exposure to the outdoor environment

14

Ft. Monmouth Education Center  “∆T” test:

loading dock

 Space use:

kitchen, dining area

 Outdoor

exposure: west wing solar 15

Loads Features and Capabilities  How does EnergyPlus calculate what it will

take to keep a zone at the desired thermal conditions? 

EnergyPlus contains the heat balance engine from IBLAST, a research version of BLAST with integrated loads and HVAC calculation.  The major enhancements of the IBLAST heat balance

engine include mass transfer and radiant heating and cooling  Essentially identical in functionality to the Loads Toolkit developed under ASHRAE Research Project (RP-987) 16

Loads Features and Capabilities (cont’d) Heat balance engine models room air as

well-stirred with uniform temperature throughout. Room surfaces are assumed to have:    

Uniform surface temperatures Uniform long and short wave irradiation Diffuse radiating and reflecting surfaces Internal heat conduction 17

EnergyPlus Model For Building Loads Conditioned Air Internal Radiation

Heat Transfer (Diffusion and Storage)

Solar Beam Tair Return Air Diffuse Solar Reflected Solar Internal Radiation

Heat & Moisture Source (P eople & Equipment)

Convection

Infiltration (Sensible & Latent)

18

Equipment & People Loads

Sensible and Latent Convection

Radiation

Equipment Occupant 19

Loads Features and Capabilities (cont’d) Three models connected to the main

heat balance routine are based on capabilities from DOE2 

Daylighting simulation  Calculates hourly interior daylight illuminance,

window glare, glare control, electric lighting controls, and calculates electric lighting reduction for the heat balance module

 

WINDOW 5-based window calculation Anisotropic sky 20

Loads Features and Capabilities (cont’d) Several other modules have been

reengineered for inclusion in EnergyPlus:  

Solar shading from BLAST Conduction transfer function calculations from IBLAST

21

Loads Features and Capabilities (cont’d)  Incorporates a simplified moisture model

known as Effective Moisture Penetration Depth (EMPD) 



Estimates moisture interactions among the space air and interior surfaces and furnishings Estimates impacts associated with moisture where detailed internal geometry and/or detailed material properties are not readily available

 User may also select a more rigorous

combined heat and mass transfer model 22

Loads Features and Capabilities (cont’d) Loads and systems portions more

tightly coupled than in BLAST or DOE-2. Loads calculated on a time step basis and passed directly to the HVAC portion. Loads not met result in zone temperature and humidity changes for the next time step. 23

Keyword: Building IDD Description (shortened) BUILDING, A1 , \field N1 , \field A2 , \field N3 , \field N4 , \field A3 ; \field

Building Name North Axis Terrain Loads Convergence Tolerance Value Temperature Convergence Tolerance Value Solar Distribution

Purpose: to control basic information

about the building location, its orientation, its surroundings, and some simulation parameters 24

Keyword: Building IDD Description (detailed) Keyword BUILDING, \unique-object \required-object \min-fields 6 User defined building name A1 , \field Building Name \required-field \default NONE N1 , \field North Axis Allows rotation of the entire \note degrees from true North building for the convenience \units deg of the user \type real True North \default 0.0 Building North North Axis Interpretation:

Angle is North Axis (+45 in this case)

25

Keyword: Building IDD Description (detailed, continued) Allows specification of immediate surroundings A2 , \field Terrain \note Country=FlatOpenCountry of the building \note Suburbs=RoughWoodedCountryTownsSuburbs \note City=CityCenter Note: Terrain \type choice mainly affects \key Country Options and their exterior \key Suburbs approximate descriptions convection \key City correlations \default Suburbs N3 , \field Loads Convergence Tolerance Value \units W Advanced user feature that \type real should be left as the default \minimum> 0.0 in most cases \default .04 26

Keyword: Building IDD Description (detailed, continued) N4 , \field Temperature Convergence Tolerance Value \units deltaC Advanced user feature that \type real should be left as the default \minimum> 0.0 in most cases \default .4 A3 ; \field Solar Distribution \note MinimalShadowing | FullExterior \note FullInteriorAndExterior \type choice \key MinimalShadowing See next two \key FullExterior slides for \key FullInteriorAndExterior descriptions \default FullExterior

27

Solar Distribution Options  Minimal Shadowing  No exterior shadowing except from door and window reveals  All direct beam solar radiation incident on floor  If no floor, direct beam solar distributed to all surfaces  Full Exterior  Exterior shadowing caused by detached shading, wings, overhangs, and door and window reveals  All direct beam solar radiation incident on floor 28

Solar Distribution Options (cont’d)  Full Interior and Exterior  





Exterior shadowing same as Full Exterior Direct beam solar radiation falls on all surfaces in the zone in the direct path of the sun’s rays Solar entering one window can leave through another window Zone must be convex:  A line passing through the zone intercepts no more than

two surfaces  An L-shaped zone is not convex

29

Convex Zones

Convex zones

Non-Convex zones 30

Keyword Example: Building IDF Example BUILDING, NONE, 0.0, Suburbs, 0.4, 0.4, FullExterior;

or BUILDING, NONE, !- Building Name 0.0, !- North Axis {deg} Suburbs, !- Terrain 0.4, !- Loads Convergence Tolerance Value {W} 0.4, !- Temperature Convergence Tolerance Value {C} FullExterior; !- Solar Distribution

31

Summary  EnergyPlus input files contain a hierarchy of

envelope input that includes the Building, Zone, Surface, and Construction definitions  Simulation of the building envelope based on a heat balance applied to a thermal zone  Buildings consist of one or more thermal zones—number of zones based on various factors including space usage, environmental conditions, etc.  EnergyPlus provides access to more detailed simulation of daylighting, windows, moisture, etc. 32

Lecture 6: Building Envelope Description (Part II)











Keywords Covered in this Lecture Zone SurfaceGeometry Surface (all types) Construction Material:Regular Material:Regular-R Material:Air 4

Review of Envelope Hierarchy Building

Surface

Zone

Zone

Zone

Surface

Surface

Surface

Material

… more surfaces

only one construction per surface

Construction Material

… more zones

Material

Material

… more materials 5

Keyword: Zone  IDD Description (shortened) ZONE, A1 , N1 , N2 , N3 , N4 , N5 , N6 , N7 , N8 , A2 ;

\field \field \field \field \field \field \field \field \field \field

Zone Name Relative North (to building) X Origin Y Origin Z Origin Type Multiplier Ceiling Height Volume Zone Inside Convection Algorithm

 Purpose: to define basic properties about a

thermal zone

6

Keyword: Zone IDD Description (detailed) Keyword ZONE, \required-object A1 , \field Zone Name User defined zone name \required-field \type alpha \reference ZoneNames N1 , \field Relative North (to building) \units deg \type real Allows rotation of the zone \default 0 with respect to the building; see north axis for building description 7

Keyword: Zone IDD Description (detailed, continued) N2 , \field X Origin \units m \type real \default 0 N3 , \field Y Origin \units m \type real \default 0 N4 , \field Z Origin \units m \type real \default 0

Origin for the “lower southwest corner” of the zone in Cartesian coordinates

8

Keyword: Zone IDD Description (detailed, continued) N5 , \field Type \maximum 1 \minimum 1 \default 1 N6 , \field Multiplier \type integer \minimum 1 \default 1 N7 , \field Ceiling Height \units m \type real \default 0 N8 , \field Volume \units m3 \type real \default 0

This is a placeholder for a future feature of the program Used to represent similar zone without having to input all of the data multiple times

Volume is used to calculate the amount of thermal capacitance in the zone air and has an impact on how quickly the zone air temperature changes

9

Keyword: Zone IDD Description (detailed, continued) A2 ; \field Zone Inside Convection Algorithm \type choice Determines the interior \key Simple convection correlation used \key Detailed by the program; optional \key CeilingDiffuser parameter \key TrombeWall \note Simple = constant natural convection (ASHRAE) \note Detailed = variable natural convection based \note on temperature difference (ASHRAE) \note CeilingDiffuser = ACH based forced and mixed \note convection correlations for ceiling diffuser \note configuration with simple natural convection \note limit \note TrombeWall = variable natural convection in an \note enclosed rectangular cavity

10

Keyword Example: Zone IDF Example ZONE,ZONE ONE, 0.0, 6.096, 0.0, 0.0, 1, 1, 0.0, 0.0, Detailed;

or ZONE, ZONE ONE, 0.0, 6.096, 0.0, 0.0, 1, 1, 0.0, 0.0, Detailed;

!!!!!!!!!!-

Zone Name Relative North (to building) {deg} X Origin {m} Y Origin {m} Z Origin {m} Type Multiplier Ceiling Height {m} Volume {m3} Zone Inside Convection Algorithm

11

Keyword: SurfaceGeometry  Three dimensional

(3D) Cartesian coordinate system  Right hand coordinate system   

X-axis points east Y-axis points north Z-axis points up

Building and/or Zone North Axis Z Axis

Y Axis

X Axis

12

Keyword: SurfaceGeometry (cont’d)  Vertex-based  Specify 3D coordinates of each corner of a surface  World Coordinates  All coordinates refer to global origin  Building and Zone north axes ignored  Zone origins ignored (except for daylighting)  Relative Coordinates  Zones relative to building  Surfaces relative to zones  Subsurfaces relative to zones 13

Keyword: SurfaceGeometry (cont’d)  Surface starting position, looking from outside  UpperLeft, UpperRight, LowerLeft, LowerRight  Order of vertex entry  Clockwise, Counterclockwise  Coordinate system  WorldCoordinateSystem, RelativeCoordinateSystem  IDF Example: SurfaceGeometry, UpperLeftCorner, CounterClockWise, WorldCoordinateSystem;

!- SurfaceStartingPosition !- VertexEntry !- SurfaceGeometryKey 14

Relative Coordinate Options  Building North Axis  Relative to true north  Rotates about bldg origin

True North

Building North Axis +30 degrees

 Zone North Axis  Relative to building north  Rotates about zone origin

Zone North Axis

 Zone Origin  Relative to building origin (0,0,0) (0,0,0)  Surface vertices in zone Building Origin

coordinates

Zone Origin (x, y, z) 15

Types of Surfaces Surface:HeatTransfer 

Surface:HeatTransfer:Sub



Surface:HeatTransfer:InternalMass

Surface:Shading:Detached 

Surface:Shading:Detached:Fixed



Surface:Shading:Detached:Building

Surface:Shading:Attached 16

Heat Transfer Surface  Surface:HeatTransfer  Walls, Roofs, Floors, Ceilings  Inside environment is always a zone  Outside environment  Exterior with or without wind and sun  Another zone surface (interzone heat transfer)  Adiabatic (internal mass with geometry)  Other Side Coefficients (user control of exterior surface temperature, ignores solar and sky radiant) 17

Heat Transfer Surface (cont’d)  Exterior surfaces cast

shadows 



Shadows only cast in the direction of the outward facing normal A roof extended beyond the walls will not cast shadows downward

 Interior surfaces do not

cast shadows  All surfaces reflect solar as diffuse inside zone 18

Heat Transfer Surface (cont’d) IDD Description (shortened) Surface:HeatTransfer, A1 , \field User Supplied Surface Name A2 , \field Surface Type (FLOOR|WALL|CEILING|ROOF) A3 , \field Construction Name of the Surface A4 , \field InsideFaceEnvironment A5 , \field OutsideFaceEnvironment \note (OtherZoneSurface|ExteriorEnvironment|Ground| \note OtherSideCoeff) A6, \field OutsideFaceEnvironment Object \note Used only if OutsideFaceEnvironment is \note OtherZoneSurface or OtherSideCoeff \note If OtherZoneSurface, specify name of \note corresponding surface in adjacent zone or \note specify current surface name for internal \note partition separating like zones 19

Heat Transfer Surface (cont’d) IDD Description (shortened, continued) A7 , A8, N1, N2 , N3, N4 , N5 , N6, N7, N8, N9, N10, N11, N12, N13, N14;

\field \field \field \field \field \field \field \field \field \field \field \field \field \field \field \field

Sun Exposure (SunExposed|NoSun) Wind Exposure (WindExposed|NoWind) View Factor to Ground Number of Surface Vertex Groups Vertex 1 X-coordinate Vertex 1 Y-coordinate Vertex 1 Z-coordinate Vertex 2 X-coordinate Vertex 2 Y-coordinate Vertex 2 Z-coordinate Vertex 3 X-coordinate Vertex 3 Y-coordinate Vertex 3 Z-coordinate Vertex 4 X-coordinate Vertex 4 Y-coordinate Vertex 4 Z-coordinate

20

Heat Transfer Subsurface Surface:HeatTransfer:Sub Windows, Doors, Glass Doors 



Only windows and glass doors transmit sunlight Can have interior windows

Must be placed on a base surface Cannot completely cover base surface 21

Door and Window Details  Outside reveal

defined by window vertices  WindowFrame AndDivider specifies details of frame, sill, inside reveal, etc.

22

Heat Transfer Subsurface (cont’d) IDD Description (shortened) Surface:HeatTransfer:Sub, A1 , \field User Supplied Surface Name A2 , \field Surface Type (WINDOW|DOOR|GLASSDOOR) A3 , \field Construction Name of the Surface \note To be matched with a construction \object-list ConstructionNames A4 , \field Base Surface Name (that subsurface attached to) A5, \field OutsideFaceEnvironment Object \note Used only if Base OutsideFaceEnvironment is \note OtherZone or OtherSideCoeff \note If OtherZone, specify name of corresponding \note subsurface in adjacent zone or specify current \note subsurface name for internal partition \note separating like zones N1, \field View Factor to Ground 23

Heat Transfer Subsurface (cont’d) IDD Description (shortened, continued) A6,

\field Name of shading control \note used for windows and glass doors only \note If not specified, window or glass door has \note no shading (blind, roller shade, etc.) A7, \field WindowFrameAndDivider Name \note Used only for exterior windows (rectangular) \note and glass doors. \note Unused for triangular windows. \note If not specified (blank), window or glass door \note has no frame or divider and no beam solar \note reflection from reveal surfaces. N2 , \field Multiplier

24

Heat Transfer Subsurface (cont’d) IDD Description (shortened, continued) N3 , N4, N5 , N6 , N7, N8, N9, N10, N11, N12, N13, N14, N15;

\field \field \field \field \field \field \field \field \field \field \field \field \field

Number Vertex Vertex Vertex Vertex Vertex Vertex Vertex Vertex Vertex Vertex Vertex Vertex

of Surface Vertex Groups 1 X-coordinate 1 Y-coordinate 1 Z-coordinate 2 X-coordinate 2 Y-coordinate 2 Z-coordinate 3 X-coordinate 3 Y-coordinate 3 Z-coordinate 4 X-coordinate 4 Y-coordinate 4 Z-coordinate 25

Shading Surface  Three types

Upper Left Corner Vertex for Overhang

 Transmittance

schedule (default is always opaque)  Automatically mirrored to cast shadows in both directions  Must specify vertices

D

A C

B

(0,0,0)

26

Shading Surface (cont’d) IDD Description (shortened) 

Similar for all three shading surface types:  Surface:Shading:Detached:Fixed  Surface:Shading:Detached:Building  Surface:Shading:Attached

Detached shading surfaces are not associated with a base surface

Surface:Shading:Attached, A1 , \field User Supplied Surface Name A2 , \field Base Surface Name A3 , \field Transmittance schedule for shading device N1 , \field Number of Surface Vertex Groups N2 , N3 , N4 , \field Vertex 1 X, Y, Z-coordinates N5 , N6 , N7 , \field Vertex 2 X, Y, Z-coordinates N8 , N9 , N10, \field Vertex 3 X, Y, Z-coordinates N11, N12, N13; \field Vertex 4 X, Y, Z-coordinates

27

Construction List material layers from outside to

inside Convection coefficients (film layers) are added automatically IDF Example: CONSTRUCTION, CEILING39, C5 - 4 IN HW CONCRETE, E4 - CEILING AIRSPACE, E5 - ACOUSTIC TILE;

!!!!-

User Defined Name Outside Layer Layer #2 Inside Layer 28

Materials for Opaque Surfaces  Material:Regular  Has thermal mass  Thickness, conductivity, density, and specific heat  Material:Regular-R  Has no thermal mass  Specify only thermal resistance  Material:Air  Also no thermal mass, just resistance  Cannot be an outside layer, no absorptances  Otherwise, modeled same as Material:Regular-R 29

Material Example MATERIAL:REGULAR, PLASTERBOARD-2, Rough, 0.01, 0.16, 950.0, 840.0, 0.9, 0.6, 0.6;

!!!!!!!!!-

Options: VeryRough, MediumRough, Rough, Name Smooth, MediumSmooth, Roughness Thickness {m} VerySmooth Conductivity {W/m-K} Density {kg/m3} Specific Heat {J/kg-K} Thermal Absorptance Solar Absorptance Visible Absorptance

 Parameters Affecting:   

Convection—Roughness Conduction—Thickness, Conductivity, Density, Specific Heat Radiation—Absorptances

 Material:Regular-R and Material:Air contain a subset

of the above information (see IDD for more details)

30

DataSets for Materials and Constructions EnergyPlus\DataSets\  BLASTMaterials.idf BLASTConstructs.idf  DOE-2Materials.idf DOE-2Constructs.idf  WindowGlassMaterials.idf  WindowGasMaterials.idf  WindowShadeMaterials.idf  WindowConstructs.idf  WindowBlindMaterials.idf 31

Materials for Moisture Transfer MaterialProperty:Moisture:MTF 

Moisture Transfer Function model

MaterialProperty:Moisture:EMPD 

Effective Mean Penetration Depth model

\DataSets\MoistureMaterials.idf

32

Summary  In EnergyPlus…  Buildings are made up of one or more Zones  Zones are made up of one or more Surfaces  Zones are “thermal zones”—basis of the heat balance solution  Surfaces are defined by a Construction  Constructions are made up of one or more Material layers  Accuracy of simulation results directly related

to accuracy of input data

33

Lecture 7: Building Modeling Questions











Potential Questions You Might Have Is every room a zone? How many

zones? How detailed should the building model be? How accurate will my results be? Do I need to do a design day run or an annual run? 4

Defining a Building Getting Started Manual 

A methodology for using EnergyPlus

Four Step Process 

Gather information



Zone the building



Create building model



Create input file 5

Step 1 - Gather Information  Location and design climate  Building description  Wall constructions  Wall sizes  Window, door, overhang details  Wall locations (shading)  Building use information  Equipment and occupancy information  Schedule information 6

Step 1 - Gather Information (cont’d) Building thermostatic controls HVAC equipment information 

Equipment types



Operating schedules



Control information

7

Step 2 – “Zone” the Building Thermal, not geometric, zones Heat storage and heat transfer surfaces Heat transfer  only when expected to

separate spaces of significantly diff temps 

Exterior Walls, Roofs, Floors

Heat storage surfaces  surfaces

separating spaces of same temperature 8

Simplifying EnergyPlus Input Simplify -- Think before typing Layout simple floor plan As few zones as necessary As few surfaces as necessary Surfaces, NOT volumes Is shading important?

9

As Few Zones As Necessary Combine similar zones Use zone multipliers wisely Combine vertically and horizontally

10 ZONES OR 6 OR 4 OR 2? 10

Rules of Thumb Reminder One zone per major exposure minimum Separate zones for different uses Separate zones for different setpoints Separate zones for different fan

systems (and radiant systems) Do not use “rooms” to determine zones

11

Step 3 - Create Building Model Heat transfer and heat storage surfaces Define equivalent surfaces Specify construction elements Compile surface and subsurface info Compile internal space gain data

12

As Few Surfaces As Necessary Combine similar surfaces Combine small surfaces with larger

surfaces Ignore minor details Use internal mass

7 WINDOWS OR 3?

13

Step 4 – Create Input File Materials and Constructions Building Geometry Internal Loads Special Features

14

Case Study  US Army Fort Monmouth education center  Temperate coastal climate, Near New York

City

 Floor area of over 13,000 sq.Ft.  Building height of 10 ft.  Total window area in excess of 1,400 sq.Ft.  May serve as many as 200 people

15

Ft. Monmouth Floor Plan 23 1

2

24

25

22

26

21 20 3

19

4

5

6

12 9

10

18

11 17

13 7

14

15

16

8

How many zones should there be? 16

Option 1: One-Zone Model 50 ft

39 ft (62 ft2) 65 ft 10 ft

(334 ft2)

20 ft

65 ft

20 ft

(113 ft2)

75.3 ft

(209 ft2)

124.6 ft

(84 ft2)

34 ft

(26 ft2)

(82 ft2)

(363 ft2) 16 ft

(42 ft2)

(61 ft2) 50 ft

43.3 ft

101 ft2)

(40 ft2)

113 ft

How accurate is this model? 17

Option 2: Six-Zone Model Five fan systems or zoning thermally Expect higher solar on south and west

Zone 1

Zone 2

Zone 4

Zone 6

Zone 5 Zone 3

18

Modeling Fort Monmouth with EnergyPlus  With appropriate detail:  EnergyPlus can convert a simple model into a powerful energy analysis  Complex interactions modeled for an entire year  Designers can then:  Size systems and plants  Examine performance of various system and plant configurations  Determine more efficient operational schemes  Calculate annual energy consumption 19

Six-Zone Model Loads 90 80

Cooling Load [kBtu/Hr]

70 Zone 1 60 Zone 2 50

Zone 3

40

Zone 4 Zone 5

30

Zone 6 20 10 0 5

6

7

8

9

10

11

12

13

14

15

16

17

18

Hours

How does this compare to 1-zone model? 20

Comparison Between One and Six-Zone Models 300

Cooling Load [Kbtu/hr]

250

200 1 Zone Cooling

150

6 Zone Cooling 100

50

0 1

3

5

7

9

11

13

15

17

19

21

23

Hours

Difference in Total Cooling Load < 10% Difference in Total Heating Load < 1% 21

Simple EnergyPlus Model Produces Incredible Results  Why? EnergyPlus captured the physics ...     

Building exterior remains the same Solar load equivalent Internal loads unchanged Internal mass accurately approximated Identical weather conditions

 Difference: unconditioned spaces

22

Detailed Model Benefits Improved accuracy Better resolution of loads for system

sizing Incredible analytical power

23

Another Aspect to Consider ...  How much of an effect does the thermal mass

of zone surfaces have on zone loads?  Comparison using Ft. Monmouth six zone model  

Standard EnergyPlus run EnergyPlus run using no thermal mass (R values)

 Use output reports from previous run to

change the surface definitions to R values only 24

Key Physical Properties  Exterior Walls  





4” Dense Face Brick 8” Heavyweight Concrete Block 6” Mineral Fiber Insulation 5/8” Gypsum

 Roof  

 

3/4” Roofing 2” Expanded Polystyrene Insulation Airspace 3/4” Acoustic Tile

 Slab on Grade Floor  

4” Concrete Tile Flooring

25

Case 1: Thermal Mass Effects  Cooling loads higher

with no mass  

Total load off by 14% Peak off by 15%

 Larger differences show

up in zones 1, 2, and 3 

Could result in oversizing of systems and plants

 Only thermal mass

changed 

Other EnergyPlus details a factor

Cooling Loads No-Mass vs. Mass Zone Total Peak 1 12% 32% 2 16% 31% 3 16% 40% 5 14% 16% 6 15% 14% All 14% 15% 26

Design Day Calculations Convenient short time period Established design day conditions easy

to obtain Fairly good estimate for system and plant sizing Will design day results be an accurate indication of long term trends?

27

Case 2: Adding Roof Insulation What will the effect of doubling the

amount of roof insulation be? Roof    

3/4” Roofing 2” Expanded Polystyrene Insulation Airspace 3/4” Acoustic Tile

Will a design day tell the whole story? 28

Design Day Heating Load Results 400

Heating Load [Kbtu/hr]

350

300 4in Insulation Roof 2in Insulation Roof

250

200

150 1

3

5

7

9

11

13

15

17

19

21

23

Hours

Daily Decrease for Heating Loads = 8%

29

Design Day Cooling Load Results Cooling Load [Kbtu/hr]

300

200 4in Insulation Roof 2in Insulation Roof 100

0 1

3

5

7

9

11

13

15

17

19

21

23

Hours

Daily Decrease for Cooling Loads = 3%

30

Annual Run Building Loads Why are the cooling loads higher with

more insulation?

Mild summer + High MRT = High summer heat retention Overall reduction in loads, but not as

expected from design day results Heating Load

Cooling Load

Peak Heating

Peak Cooling

Total Loads

Cheap Roof

468000

147500

588

289

615500

Better Roof

417700

150700

561

282

568400

Annual Diff's

10.75%

-2.17%

4.66%

2.42%

7.65%

31

Let's Change the Weather. . .  Champaign, Illinois  Temperate inland climate, south of Chicago  Compare increased roof insulation  Design day heating and cooling loads both

decreased  Annual building loads also decreased  EnergyPlus "changed" the weather for every hour of the year  EnergyPlus never forgets the physics! 32

Summary Simple models can produce good results Thermal mass can have a significant

effect on loads Design day calculations can be misleading Annual runs pick up mild weather effects

33

Lecture 8: Schedules and Internal Heat Gains


Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways:    

Location/exterior environment Construction/building envelope Space usage/interior environment HVAC system

 Thermal simulation requires information about the functions

taking place inside the building and how these might add or subtract heat from the zones  Thermal simulation requires information on air leakage to and from the building to determine its effect on the building heating and cooling needs  Nothing is constant inside a building—people come and go, lights and equipment gets turned on and off, etc.—and the thermal simulation needs details on what is happening through the day and year within a building 2


internal heat gains impact and space and how to specify them 

People, Lights, Equipment, etc.



Infiltration



Schedules

3

Keywords Covered in this Lecture  ScheduleType  DaySchedule  WeekSchedule  Schedule  People and AngleFactorList  Lights  Equipment—Electric, Gas, Hot Water, Steam,

Baseboard (scheduled), Other  Exterior Equipment  Infiltration

4

Schedules  In general, schedules are a way of specifying

how much or many of a particular quantity is present or at what level something should be set, including:     

Occupancy density Occupancy activity Lighting Thermostatic controls Shading element density 5

Schedules (cont’d) For internal gains, schedules allow us to

come a little closer to the real variation of building quantities than single values

% of peak occupancy

peak average

reality how we account for internal gains

6

Schedules in EnergyPlus  EnergyPlus uses a hierarchy of schedule

pieces to create unique schedules  DaySchedule: 24 hour period of schedule values  WeekSchedule: Consists of various DaySchedule definitions for an entire week  Schedule: Consists of various WeekSchedule definitions for an entire year  ScheduleType: Optional feature that allows for some validation and limitation of schedules (avoid mistakes) 7

ScheduleType  Used to validate schedule values (optional) ScheduleType, Any Number; ScheduleType, Fraction, 0.0:1.0, CONTINUOUS; ScheduleType, Temperature, -60:200, CONTINUOUS; ScheduleType, Control Type, 0:4, DISCRETE;

!- ScheduleType Name !- ScheduleType Name !- range !- Numeric Type !- ScheduleType Name !- range !- Numeric Type !- ScheduleType Name !- range !- Numeric Type

Notes: Maximum and minimum of range (inclusive) separated by colon Discrete refers to distinct integer values 8 Continuous to any value in the range

DaySchedule  The day description is

simply a name and the 24 hourly values associated with that name  Other forms   

DaySchedule:Interval DaySchedule:List Can handle subhourly schedule changes

 Hour 1 is Midnight to 1am

DAYSCHEDULE, OC-1, Fraction, 0.0, 0.0, 0.0, 0.0, 0.0, . . . 1.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0;

!!!!!!!-

Name ScheduleType Hour 1 Hour 2 Hour 3 Hour 4 Hour 5

!!!!!!!!-

Hour Hour Hour Hour Hour Hour Hour Hour

17 18 19 20 21 22 23 24

9

WeekSchedule  The week description has an identifier and 12 names

corresponding to previously defined DaySchedules

WEEKSCHEDULE, ActWeekSchd, ActDaySchd2, ActDaySchd1, ActDaySchd1, ActDaySchd1, ActDaySchd1, ActDaySchd1, ActDaySchd2, ActDaySchd3, ActDaySchd4, ActDaySchd4, ActDaySchd3, ActDaySchd3;

!- Name !- Sunday DAYSCHEDULE Name !- Monday DAYSCHEDULE Name !- Tuesday DAYSCHEDULE Name !- Wednesday DAYSCHEDULE Name !- Thursday DAYSCHEDULE Name !- Friday DAYSCHEDULE Name !- Saturday DAYSCHEDULE Name !- Holiday DAYSCHEDULE Name !- SummerDesignDay DAYSCHEDULE Name !- WinterDesignDay DAYSCHEDULE Name !- CustomDay1 DAYSCHEDULE Name !- CustomDay2 DAYSCHEDULE Name 10

Schedule  Annual schedule contains an identifier and the names

and from-thru dates of the week schedules associated with the annual schedule  Up to 52 week schedules can be specified, allowing unique specification of every day of the year  Other forms  

WeekSchedule:Compact Schedule:Compact

SCHEDULE, OCCUPY-1, Fraction, OC-WEEK, 1, 1, 12, 31;

!!!!!!!-

Name ScheduleType Name of WEEKSCHEDULE 1 Start Month 1 Start Day 1 End Month 1 End Day 1

Repeat as needed

11

Complete Schedule Specification Example of an EnergyPlus Schedule: ScheduleType, Any Number; DaySchedule, Weekday, Any Number, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.10, 0.50, 1.00, 1.00, 1.00, 1.00, 0.50, 1.00, 1.00, 1.00, 0.50, 0.10, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00; DaySchedule, Weekend, Any Number, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00; WeekSchedule, Office Occupancy Schedule, Weekend, Weekday, Weekday, Weekday, Weekday, Weekday, Weekend, Weekend, Weekend, Weekend, Weekend, Weekend; Schedule, Office Occupancy Schedule, 1, 1, 12, 31; 12

Types of Internal Gains People Lights Equipment Infiltration See “Input Output Reference” –

Space Gains

13

Heat Additions from Internal Gains  Sensible vs. Latent  Sensible—energy addition associated with (drybulb) temperature change in zone  Latent—energy addition associate with moisture/humidity change in zone  Sensible Heat Gains  Convection  Thermal (Long Wavelength) Radiation  Visible (Short Wavelength) Radiation (generally lights only) 14

People  Peak Value  Schedule  Radiant fraction (remainder of sensible gain is

convection)  Activity level schedule (W/person) 

Total heat gain—broken up into sensible and latent fractions within the program automatically

 Thermal comfort reports  Fanger  Pierce Two-Node  Kansas State University Two-Node 15

People: Example PEOPLE, EAST ZONE, 3.000000, BLDG Sch 1, 0.3000000, Activity Sch, EAST ZONE, ZoneAveraged, , Work Eff Sch, Clothing Sch, Air Velo Sch, Fanger;

!!!!!!!!!!!!-

Zone Name Number of People Number of People SCHEDULE Name (real--fraction) Fraction Radiant Activity level SCHEDULE Name (units W/person) PEOPLE Group Name MRT Calculation Type Surface Name/Angle Factor List Name Work Efficiency SCHEDULE Name (0.0-1.0,real) Clothing Insulation SCHEDULE Name (real) Air Velocity SCHEDULE Name (units m/s, real) Thermal Comfort Report Type (Fanger, Pierce, KSU)

Options are ZoneAveraged, SurfaceWeighted, or AngleFactor; determines the position that MRT is calculated at (center of zone, near a surface, or at a particular point through user supplied angle factors) Apply only to thermal comfort models, not the heat balance 16

People: Other Notes  Estimating the Number of People  Based on type of space/activity  See ASHRAE Standard 62 for estimates  Example: 7 people/100m2 for an office setting  Estimating the Activity Level  Based on activity within the zone  See ASHRAE Handbook of Fundamentals, Thermal Comfort Chapter or Nonresidential Cooling and Heating Load Calculation Procedures Chapter for estimates  Example: 115W/person for seated, light office work  Estimating the Percent Radiant  Common values range from 30-40% (0.3-0.4) 17

AngleFactorList  Allows user to specify angle factors for

various surfaces to define influence on Mean Radiant Temperature (MRT) for thermal comfort evaluation

AngleFactorList, West Wing Angle Factors, West Wing, Zone001:Surf001, 0.20, Zone001:Surf002, 0.20, Zone001:Surf003, 0.20, Zone001:Ceiling001, 0.15, Zone001:Floor001, 0.25;

!!!!!!!!!!!!-

Angle Factor Zone Name Surface Name Angle Factor Surface Name Angle Factor Surface Name Angle Factor Surface Name Angle Factor Surface Name Angle Factor

List Name 1 1 2 2 3 3 4 4 5 5

MRT =

Number of Surfaces

∑ (AF) T i =1

i

i

18

Lights Peak Value (all sensible) Schedule Radiant, visible, replaceable, return air

fractions (remainder is convection) Meter end use category LIGHTS, EAST ZONE, BLDG Sch 3, 1464.375, 0.0000000E+00, 0.2000000, 0.2000000, 0.0000000E+00, GeneralLights;

!!!!!!!!-

Zone Name SCHEDULE Name Design Level {W} Return Air Fraction Fraction Radiant Fraction Visible Fraction Replaceable LightsEndUseKey

19

Lights: Other Notes Estimating the Input for Lighting Level  Count the number and wattage of bulbs in zone  Estimate using information from:  Typically ranges from 1.0 – 2.0 W/ft2,

example: 1.3 W/ft2 for office setting  ASHRAE Standard 90.1  ASHRAE Handbook of Fundamentals, Nonresidential Cooling and Heating Load Calculation Procedures Chapter 20

Electric Equipment Peak Value Schedule Latent fraction is fraction of total Radiant and lost fractions of sensible

only (remainder of sensible is convection) ELECTRIC EQUIPMENT,

Basically, energy that does not affect the zone heat balance (vented to exterior environment)

NORTH ZONE, BLDG Sch 2, 2928.751, 0.0, 0.3, 0.0;

!!!!!!-

Zone Name SCHEDULE Name Design Level {W} Fraction Latent Fraction Radiant Fraction Lost

21

Electric Equipment: Other Notes  Estimating the Input for Design Level 



See ASHRAE Handbook of Fundamentals, Nonresidential Cooling and Heating Load Calculation Procedures Chapter for approximate levels for individual components Note: Nameplate ratings are generally not good estimates of power consumption of electrical equipment (example—nameplates might add up to 35 W/m2 but actual consumption might only be 8W/m2 in an office setting) 22

Other Types of Equipment Other equipment types in EnergyPlus

that have same input format as Electric Equipment (just a different keyword) 

Gas Equipment



Hot Water Equipment



Steam Equipment



Other Equipment

23

“Scheduled” Baseboard Heaters  Moderately controllable baseboard heaters

that do not interact with the rest of the HVAC system  Keyword is “Baseboard Heat”  Baseboard Heat is first priority and will react based on outside dry-bulb temperature and input definition  Baseboard that interacts with the HVAC system and controlled based on zone temperature under the following keywords:  

BASEBOARD HEATER:Water:Convective BASEBOARD HEATER:Electric:Convective 24

Baseboard Heat Example Example of Baseboard Heat usage: BASEBOARD HEAT, North Zone , !- Zone Name Baseboard Availability Schedule , !- SCHEDULE Name 15000, !- Capacity at low temperature in W (> 0) 32, !- Low Temperature in degrees C 0, !- Capacity at high temperature in W (>= 0) 65, !- High Temperature in degrees C 0.3; !- Fraction Radiant (remainder of heat is convective)

Response:

Baseboard Output (W) 15000 10000 5000 0 30

40

50

60

70

Outside Dry-Bulb Temperature

25

Exterior Equipment Convenient way to account for elements

on exterior of building that add to overall energy consumption of site but do not affect heat balance of any zones 

ExteriorLights



ExteriorFuelEquipment

ExteriorWaterEquipment ExteriorLights, Outside Lighting, ExtLightingSched, 200.0;

!!!!-

only used for reporting, does not affect loads Descriptive Name SCHEDULE Name Design Level (Watts)

26

Infiltration What is it? 

Definition: uncontrolled or unintended flow of outdoor air into a building due to…  Cracks and other unintentional openings  Normal use of exterior doors  Through building materials

27

Infiltration (cont’d) What it’s not: 



Exfiltration: uncontrolled flow of indoor air out of the building, caused by “pressurizing” the building through a mechanical system (no effect on zone heat balance but effect on HVAC system) Ventilation: purposeful opening of windows or doors to promote air exchange with the outside environment (see future lecture) 28

Infiltration: Causes Cause: pressure differential  Flow of mass from higher pressure to lower pressure area Driving forces:  Wind  Buoyancy or “stack” effect  HVAC system  Note: all of these can vary based on location within a building 29

Accounting for Infiltration Heat Gain/Loss Difficult to estimate More sophisticated estimates generally n

take a form similar to: Q=c(∆p)

Estimation based on either ACH or

“crack” method 

See ASHRAE Handbook of Fundamentals, Ventilation and Infiltration Chapter for more details 30

ACH: Air Changes per Hour Definition: fraction of room air volume

exchanged with outside air in a given hour An ACH of 1.0 means that the entire air volume of a space is replaced with outside air each hour  

Heat gain/loss can be significant Effect moderated by energy storage within the building 31

Infiltration in EnergyPlus Example from an IDF file: INFILTRATION, !- Infiltration is specified as a design level which is modified !- by a schedule fraction, temperature difference and wind speed: !- Infiltration = Idesign * Fschedule * !(A + B*|Tzone-Todb| + C*WindSpd + D * WindSpd**2) West Wing, !- Zone Name CONSTANT, !- SCHEDULE Name (Fschedule in Equation) 0.12, !- Design Volume Flow Rate in m3/s (Idesign in Equation) 1.0, !- Constant Term Coefficient (“A” in Equation) 0.0, !- Temperature Term Coefficient (“B” in Equation) 0.0, !- Velocity Term Coefficient (“C” in Equation) 0.0; !- Velocity Squared Term Coefficient (“D” in Equation)

32

Summary  Schedules are a vital part of EnergyPlus input

and play a role in the definition of many different components  Schedules are a hierarchy of:   

Day schedules Week schedules Schedules

 Scheduled heat gains/losses such as People,

Lights, Equipment, Infiltration, etc. can have a significant impact on conditions within a zone and must be taken into account 33

Lecture 9: Windows and Daylighting


Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways:  Location/exterior environment  Construction/building envelope  Space usage/interior environment  HVAC system  Building consume approximately one-third of all

energy used nationally—lighting accounts for about one third of building energy use  Daylighting has the potential to significantly reduce the amount of energy spent on lighting  Proper modeling of windows is important to both daylighting studies and energy analysis since it has a significant impact on both of these areas 2

Purpose of this Lecture Gain an understanding of how to  

Specify windows in EnergyPlus Specify and control daylighting features within a zone

3

Keywords Covered in this Lecture  Material:WindowGlass  Material:WindowGas  Material:WindowGasMixture  Material:WindowShade  Material:WindowBlind  WindowShadingControl  WindowFrameAndDivider  WindowGapAirFlowControl  Daylighting:Simple and Daylighting:Detailed 4

Windows

glass gas 5

Material:WindowGlass Non-opaque solid layer used to

construct windows

More examples from DOE-2 library in file WindowGlassMaterials.idf

MATERIAL:WindowGlass, SPECTRAL PANE, !- Name Spectral, !- Optical Data Type SpectralDataSet1, !- Name of Window Glass Spectral Data Set 0.0099, !- Thickness {m} 0.0, !- Solar Transmittance at Normal Incidence 0.0, !- Solar Reflectance at Normal Incidence: Front Side 0.0, !- Solar Reflectance at Normal Incidence: Back Side 0.0, !- Visible Transmittance at Normal Incidence 0.0, !- Visible Reflectance at Normal Incidence: FrontSide 0.0, !- Visible Reflectance at Normal Incidence: Back Side 0.0, !- IR Transmittance at Normal Incidence 0.84, !- IR Hemispherical Emissivity: Front Side 0.84, !- IR Hemispherical Emissivity: Back Side 0.80; !- Conductivity {W/m-K}

6

Material:WindowGas Non-opaque gaseous layer used to

construct windows 



Gas type can be: Air, Argon, Krypton, Xenon, or Custom Custom requires properties (curve fit coefficients) for conductivity, viscosity, and specific heat as well as the gas molecular weight

More examples from DOE-2 library in file WindowGasMaterials.idf

MATERIAL:WindowGas, WinAirGap, !- Name AIR, !- Gas Type 0.013; !- Thickness {m}

7

Material:WindowGasMixture Allows a custom mixture of gases to

construct a non-opaque gaseous layer used for windows 



Gas type can be: Air, Argon, Krypton, or Xenon User defines up to four gases in mixture Material:WindowGasMixture, MyWinGasMix, !- Name 0.0127, !- Thickness 2, !- Number of gases in mixture Air, !- Gas Type - Gas #1 0.5, !- Fraction - Gas #1 Argon, !- Gas Type – Gas #2 0.5; !- Fraction – Gas #2

8

Constructing Windows Same as a regular construction

definition except using window glass, window gas, and/or window gas mixture

CONSTRUCTION, ELECTRO-CON-DARK, ELECTRO GLASS DARK STATE, WinAirGap, SPECTRAL PANE;

!!!!-

Name Outside Material Layer Material Layer #2 Inside Material Layer

9

Material:WindowShade Allows specification of window shades 

Becomes part of window shading control

More examples from DOE-2 library in file WindowShadeMaterials.idf

MATERIAL:WindowShade, MEDIUM REFLECT - MEDIUM TRANS SHADE, !- Name 0.4, !- Solar transmittance 0.5, !- Solar reflectance 0.4, !- Visible transmittance 0.5, !- Visible reflectance 0.9, !- Thermal emissivity 0.0, !- Thermal transmittance 0.005, !- Thickness {m} 0.1, !- Conductivity {W/m-K} 0.05, !- Shade-to-glass distance {m} 0.5, !- Top opening multiplier 0.5, !- Bottom opening multiplier 0.5, !- Left-side opening multiplier 0.5, !- Left-side opening multiplier 0.0; !- Air-flow permeability 10

Material:WindowBlind Allows specification of window blinds 

Becomes part of window shading control



Example on next slide…



More examples from DOE-2 library in file WindowBlindMaterials.idf

11

Material:WindowBlind MATERIAL:WindowBlind,BLIND WITH HIGH REFLECTIVITY SLATS, HORIZONTAL, !- Slat orientation 0.025, !- Slat width [1"] (m) 0.01875, !- Slat separation [3/4"] (m) 0.001, !- Slat thickness (m) 45.0, !- Slat angle (deg) 0.9, !- Slat conductivity (W/m-K) 0.0, !- Slat beam solar transmittance 0.8, !- Slat beam solar reflectance, front side 0.8, !- Slat beam solar reflectance, back side 0.0, !- Slat diffuse solar transmittance 0.8, !- Slat diffuse solar reflectance, front side 0.8, !- Slat diffuse solar reflectance, back side 0.0, !- Slat beam visible transmittance 0.8, !- Slat beam visible reflectance, front side 0.8, !- Slat beam visible reflectance, back side 0.0, !- Slat diffuse visible transmittance 0.8, !- Slat diffuse visible reflectance, front side 0.8, !- Slat diffuse visible reflectance, back side 0.0, !- Slat IR (thermal) hemispherical transmittance 0.9, !- Slat IR (thermal) hemispherical emissivity, front side 0.9, !- Slat IR (thermal) hemispherical emissivity, back side 0.050, !- Blind-to-glass distance 0.5, !- Blind top opening multiplier 0.5, !- Blind bottom opening multiplier 0.5, !- Blind left-side opening multiplier 0.5, !- Blind right-side opening multiplier , !- Minimum slat angle (deg) ; !- Maximum slat angle (deg)

12

WindowShadingControl Referenced by exterior window surface

definitions Shading types: 





Shade (interior, exterior, or between glass)—WindowShade Blind (interior, exterior, or between glass)—WindowBlind Switchable glazing 13

WindowShadingControl (cont’d)  Reference to either a construction or a

material name  Many shading control variations:  

 



Always on or off or on as per schedule On if high solar, glare, air temperature, cooling load, or combinations of these Meet daylighting illuminance setpoint On at night if heating required or low temperatures with various daytime controls Off at night while on during daytime for cooling conditions and high solar on windows 14

WindowShadingControl (cont’d) Other controls 

Various setpoints



Glare control



Several control options for blind slat angles

WINDOWSHADINGCONTROL, WIN-CONTROL-GLARE, SwitchableGlazing, ELECTRO-CON-DARK, OnIfHighGlare, , 0.0, NO, YES, , , ;

!!!!!!!!!!!-

User Supplied Shading Control Name Shading Type Name of construction with shading Shading Control Type Schedule Name Solar/Load/Temp SetPoint {W/m2, W or deg C} Shading Control Is Scheduled Glare Control Is Active Material Name of Shading Device Type of Slat Angle Control for Blinds Slat Angle Schedule Name

15

WindowFrameAndDivider Used to define information about

frames and dividers Can be significant portion of heat transfer characteristics of window Includes physical properties (width, projections, number of dividers) as well as thermal properties Example on next slide… 16

WindowFrameAndDivider (cont’d) WindowFrameAndDivider, TestFrameAndDivider, !- User Supplied Frame/Divider Name 0.05, !- Frame Width {m} 0.05, !- Frame Outside Projection {m} 0.05, !- Frame Inside Projection {m} 5.0, !- Frame Conductance {W/m2-K} 1.2, !- Ratio of Frame-Edge Glass Conductance to Center-Of-Glass Co 0.8, !- Frame Solar Absorptance 0.8, !- Frame Visible Absorptance 0.9, !- Frame Thermal Hemispherical Emissivity DividedLite, !- Divider Type 0.02, !- Divider Width {m} 2, !- Number of Horizontal Dividers 2, !- Number of Vertical Dividers 0.02, !- Divider Outside Projection {m} 0.02, !- Divider Inside Projection {m} 5.0, !- Divider Conductance {W/m2-K} 1.2, !- Ratio of Divider-Edge Glass Conductance to Center-Of-Glass 0.8, !- Divider Solar Absorptance 0.8, !- Divider Visible Absorptance 0.9; !- Divider Thermal Hemispherical Emissivity 17

WindowGapAirFlowControl Used to allow ventilation of air gap in

windows with either inside or outside air Air can be vented to inside or outside Can be scheduled WindowGapAirflowControl,

!!Zn001:Wall001:Win002, !InsideAir, !OutsideAir, !0.008, !!AlwaysOnAtMaxFlow, !No, !; !-

Used to control forced airflow through a gap between glass layers Name of Associated Window Airflow Source Airflow Destination Maximum Airflow (m3/s per m of glazing width) (5.2 cfm for 1m x 1m window) Airflow Control Type Airflow Has Multiplier Schedule? Name of Airflow Multiplier Schedule 18

Daylighting DAYLIGHTING:SIMPLE 

Specify useful fraction of solar gain

DAYLIGHTING:DETAILED 

Calculates illuminance

Only one type per zone May use different types in same run

19

Daylighting:Simple Effectiveness method 

Fraction beam usable



Fraction diffuse usable



Schedule

LIGHTS 

Fraction replaceable



All lights on one control 20

Daylighting:Simple Light Control Sensible and Latent

Beam Solar Sky Diffuse

Ground Diffuse

21

Daylighting:Detailed Methodology Calculated illuminance level External factors 

Sky condition



Sun position



Ground reflectance



External shading and obstructions

22

Daylighting:Detailed Methodology (cont’) Window factors  Size  Position  Transmittance  Shades Internal factors  Interior surface visible absorptance  Position of daylighting reference point 23

Daylighting:Detailed Light Control 1

Light Control 2

Uncontrolled Sensible and Latent

Beam Solar Sky Diffuse

Reference Pt 2

Ground Diffuse Reference Pt 1

24

Daylighting Calculation Daylight factors

 









Ratios of interior illuminance or luminance to exterior horizontal illuminance Contribution of direct light from each window to each reference point Contribution of reflected light from walls, floor and ceiling Window luminance and window background luminance used to determine glare Factors calculated for hourly sun positions on sun-paths for representative days of the run period 25

Daylighting Calculation (cont’d)  

 



Daylighting calculation performed each heatbalance time step when the sun is up Daylight factors at each reference point interpolated using the current time step’s sun position and sky condition Illuminance found by multiplying daylight factors by exterior horizontal illuminance If glare control, then automatically deploy window shading, if available, to decrease glare below a specified comfort level Similar option uses shades to control solar gain 26

Electric Lighting Control     

Electric lights full-on assumed to provide the setpoint illuminance – regardless of schedule Electric lighting control system simulated to determine fraction of lighting for each lighting zone Based on daylighting illuminance level regardless of actual electric lighting input power Zone lighting electric reduction factor passed to thermal calculation Heat gain from lights and power input reduced

27

Continuous Dimming 1.0 Increasing daylight illuminance

Zero daylight illuminance

Fractional light output

Minimum light output fraction 0 0

1.0 Fractional input power Minimum input power fraction

28

Stepped Lighting Control Step 1 1.0 Step 2 Fractional input power

Step 3

0 0

Daylight illuminance Illuminance set point 29

Daylighting:Detailed Inputs  1 or 2 illuminance reference points  Specific point(s) in zone (X,Y,Z position)  Zone coordinate system – relative to zone origin  If zone origins are all 0,0,0, then equivalent to world coordinates  1 to 3 lighting zones  Controlled by reference point 1  Controlled by reference point 2  Uncontrolled  Specify fraction of lighting power for each zone

30

Daylighting:Detailed Inputs (cont’d) Illuminance setpoint(s) [lux] Lighting control type 

Continuous – stay on at minimum



Continuous – turn off at minimum



Stepped – automatic



Stepped – manual with probability



Minimum lighting output and power levels 31

Daylighting:Detailed Inputs (cont’d) Glare control of window shades 

Direction of view



Maximum glare level

32

Daylighting:Detailed Example DAYLIGHTING:DETAILED, Zone 2, 1, 2.5, 2, 0.8, 2.5, 8, 0.8, 0.4, 0.4, 500, 500, 1, 0, 0, 22, 0.3, 0.2, 1, 1;

!!!!!!!!!!!!!!!!-

Zone Name Total Daylighting Reference Points X,Y,Z-coordinates of first reference point {m} X,Y,Z-coordinates of second reference point {m} Fraction of zone controlled by first ref. point Fraction of zone controlled by second ref. point Illuminance setpoint at first reference point {lux} Illuminance setpoint at second reference point {lux} Lighting control type Azimuth angle of view direction clockwise from zone y-axis (for glare calculation) {deg} Maximum allowable discomfort glare index Minimum input power fraction for continuous control Minimum light output fraction for continuous control Number of steps (excluding off) for stepped control Probability lighting will be reset in manual control

33

Ground Reflectance GroundReflectance 12 monthly values Affects: 

Solar gains



Daylighting

Snow Ground Reflectance Modifiers

34

Daylighting Modeling Guidelines Do not use window multipliers  Different window positions would be lost Zone multipliers  Beneficial to get room proportions correct  Can only use if external shading not affected by zone position Interior surfaces within a zone do not

block direct light for daylighting calcs

35

Representative Room with Zone Multiplier

36

Model Unique Rooms as Individual Thermal Zones

A C

D

B

37

Multiple Lighting Zones Second Reference Point Fraction of Zone Controlled by Second Reference Point = 0.5 First Reference Point Fraction of Zone Controlled by First Reference Point = 0.5

38

Daylighting in Part of a Thermal Zone

B

A

C

D

Interior window – no daylighting passes through First Reference Point

Exterior window 39

Shading Surfaces for Daylighting  Opaque  No daylight transmitted (according to manual, I/O ref. pp 191-192)  However, shadowing surface transmittance schedule does impact daylighting currently in some cases (may be a bug)  Black  Do not reflect light  For example, reflection from top of overhang onto window above not calculated 40

Summary Windows are a means of providing solar

heat gain and natural lighting to spaces within a building EnergyPlus requires specification of the composition of window components as well as any shading strategy being used Daylighting calculations can show the possible reduction in electric lighting

41

Lecture 10: Zone and Modeling Controls, Simple HVAC for Load Calculations


Importance of this Lecture to the Simulation of Buildings  Almost all buildings are “controlled thermal

environments”  To calculate how much energy is required to maintain the appropriate thermal environment, an energy simulation program needs the control strategy  Resulting heating and cooling loads can be a good basis for comparing different envelope designs before addressing HVAC issues  Simulation programs always have “details”— this lecture discusses some of the simulation parameters that might be of importance to some runs

2

Purpose of this Lecture Gain an understanding of how to: 





Obtain heating and cooling loads for zones without defining an entire HVAC system Calculate approximate air flow rates for zones Control some of the modeling details of a thermal simulation using EnergyPlus

3

Keywords Covered in this Lecture  Zone Control:Thermostatic  Single Heating Setpoint, Single Cooling

Setpoint, Dual Setpoint With Deadband  Schedule (review)  Purchased Air (and some affiliated input)  Simulation Control Parameters: TimeStep in Hour, Inside/Outside Convection Algorithm, Sky Radiance Distribution, Solution Algorithm, Shadowing Calculation, Convection Coefficients 4

Thermostatic Control Controls zone to a specified temperature Control options include:

0 – Uncontrolled

No heating or cooling, zone “floats”

1 – Single heating setpoint

Heats to setpoint, no cooling

2 – Single cooling setpoint

Cools to setpoint, no heating

3 – Single heating/cooling setpoint 4 – Dual setpoint with deadband

“Perfect” control

Heating below lower setpoint, Cooling above higher setpoint, Zone “floats” in deadband between setpoints

5

Zone Thermostat Basic Format of EnergyPlus Input: ZONE CONTROL:THERMOSTATIC, Zone Name, Control Type SCHEDULE Name, Control Type #1, !-Single Heating Setpoint  Control type sched = 1 !-Single Cooling SetPoint  Control type sched = 2 !-Single Heating Cooling Setpoint  Control type sched = 3 !-Dual Setpoint with Deadband  Control type sched = 4 Control Type Name #1, …(Repeat for each thermostatic control type in zone)… ;

6

Zone Thermostat - Example ZONE CONTROL:THERMOSTATIC, SPACE1-1 Control, SPACE1-1, Zone Control Type Sched, Single Cooling Setpoint, Cooling Setpoint with Setback, Single Heating Setpoint, Heating Setpoint with Setback;

!!!!!!!-

Thermostat Name Zone Name Control Type SCHEDULE Name Control Type Control Type Name Control Type Control Type Name

Schedules of setpoint temperatures (example on slide 9); allows setpoint temperature to vary (i.e., setback) Schedule of control type parameter (0-4); determines which control type is valid at a particular time

7

Zone Thermostat Control Type Schedule DAYSCHEDULE, Summer Control Type Day Sch, Control Type, 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2; ! 2=single cool SP DAYSCHEDULE, Winter Control Type Day Sch, Control Type, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1; ! 1=single heat SP WEEKSCHEDULE, Summer Control Type Week Sch, Summer Control Type Day Sch, . . . ; WEEKSCHEDULE, Winter Control Type Week Sch, Winter Control Type Day Sch, . . . ;

Control Type Schedule

SCHEDULE, Zone Control Type Sched, Control Type, heating Winter Control Type Week Sch, 1,1, 3,31, Summer Control Type Week Sch, 4,1, 9,30, JFMA Winter Control Type Week Sch, 10,1, 12,31;

cooling

heating

MJJASOND

Values can change hourly if necessary (0-4) to model situations such as heating/cooling during the day and heating only at night for freeze protection

8

Zone Thermostat Heating Setpoint Object SINGLE HEATING SETPOINT, Heating Setpoint with Setback, !- Setpoint control object name Heating Setpoints; !- Setpoint schedule DAYSCHEDULE, Heating Setpoint Day Sch, Temperature, 15.,15.,15.,15.,15.,15.,15.,20.,20.,20.,20.,20.,20.,20.,20.,20.,20., 15.,15.,15.,15.,15.,15.,15.; WEEKSCHEDULE, Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint

Week Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch, Day Sch;

!- Name !- Sunday DAYSCHEDULE Name !- Monday DAYSCHEDULE Name !- Tuesday DAYSCHEDULE Name !- Wednesday DAYSCHEDULE Name !- Thursday DAYSCHEDULE Name !- Friday DAYSCHEDULE Name !- Saturday DAYSCHEDULE Name !- Holiday DAYSCHEDULE Name !- SummerDesignDay DAYSCHEDULE Name !- WinterDesignDay DAYSCHEDULE Name !- CustomDay1 DAYSCHEDULE Name !- CustomDay2 DAYSCHEDULE Name

SCHEDULE, Heating Setpoints, Temperature, Heating Setpoint Week Sch, 1,1, 12,31;

no conditioning 20 15

heating midnight 6am

noon

6pm

9

Set Point Objects - Examples SINGLE HEATING SETPOINT, HeatingSetpoint, Htg-SetP-Sch;

!- Name !- Setpoint Temp SCHEDULE Name

SINGLE COOLING SETPOINT, CoolingSetpoint, Clg-SetP-Sch;

!- Name !- Setpoint Temp SCHEDULE Name

DUAL SETPOINT WITH DEADBAND, DualSetPoint, !- Name Htg-SetP-Sch, !- Heating Setpoint Temp SCHEDULE Name Clg-SetP-Sch; !- Cooling Setpoint Temp SCHEDULE Name

10

Purchased Air  Used to compute zone heating/cooling loads

without modeling an HVAC system  Unlimited capacity at specified temperature and humidity  Controls only Zone dry bulb temperature  Resulting humidity level calculated  Controlled by Zone thermostat (dry bulb setpoint)  Calculates required flow rate at specified supply air temperature

11

Purchased Air – Example PURCHASED AIR, Zone1Air, !- Purchased Air Name NODE_1, !- Zone Supply Air Node Name 50, !- Heating Supply Air Temp {C} 15, !- Cooling Supply Air Temp {C} 0.02, !- Heating Supply Air Humidity Ratio {kg-H20/kg-air} 0.02; !- Cooling Supply Air Humidity Ratio {kg-H20/kg-air} CONTROLLED ZONE EQUIP CONFIGURATION, RESISTIVE ZONE, Zone1Equipment, Zone1Inlets, , NODE_4,NODE_5; ZONE EQUIPMENT LIST, Zone1Equipment, PURCHASED AIR, Zone1Air, 1, 1; NODE LIST, Zone1Inlets, NODE_1;

These keywords will be discussed in more detail in a future lecture; all are required to get purchased air to work Note that the colors in the above example denote the interconnections of these different statements

12

Complete Purchased Air Example (Everything you need to condition a zone) SCHEDULETYPE,ControlType,0:4,DISCRETE; DAYSCHEDULE,Zone Control Day, ControlType,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4; WEEKSCHEDULE, Zone Control Week, Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day, Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day,Zone Control Day; SCHEDULE, Zone Control Type Schedule, ControlType, Zone Control Week,1,1,12,31; DAYSCHEDULE,Heat Temp 5,Temperature, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0; DAYSCHEDULE,Cool Temp 5,Temperature, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6, 25.6; WEEKSCHEDULE,HEAT-DEAD BAND, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5, Heat Temp 5; WEEKSCHEDULE,COOL-DEAD BAND, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5, Cool Temp 5; SCHEDULE,ZONE 1 Heating Setpoints,Temperature,HEAT-DEAD BAND, 1, 1,12,31; SCHEDULE,ZONE 1 Cooling Setpoints,Temperature,COOL-DEAD BAND, 1, 1,12,31; ZONE CONTROL:THERMOSTATIC, ZONE 1 CONTROLS, ZONE 1,Zone Control Type Schedule,DUAL SETPOINT WITH DEADBAND, ZONE 1 SETPOINTS; DUAL SETPOINT WITH DEADBAND, ZONE 1 SETPOINTS,ZONE 1 Heating Setpoints,ZONE 1 Cooling Setpoints; PURCHASED AIR, ZONE 1 PURCHASED AIR, ZONE 1 INLETS, !- Zone Supply Air Node 50, !- Heating Supply Air Temperature {C} 13, !- Cooling Supply Air Temperature {C} 0.015, !- Heating Supply Air Humidity Ratio {kg-H2O/kg-Air} 0.010; !- Cooling Supply Air Humidity Ratio {kg-H2O/kg-Air} CONTROLLED ZONE EQUIP CONFIGURATION, ZONE 1, ZONE 1 EQUIPMENT, ZONE 1 INLETS,, ZONE 1 NODE, ZONE 1 OUTLET; ZONE EQUIPMENT LIST, ZONE 1 EQUIPMENT, PURCHASED AIR, ZONE 1 PURCHASED AIR, 1, 1; NODE LIST, ZONE 1 INLETS,ZONE 1 INLET;

13

TimeStep in Hour EnergyPlus is a “sub-hourly” simulation

program—capable of simulating the building at time steps of less than one hour Example:

TIMESTEP IN HOUR, 4; !- Number of time steps in an hour--validity 1 to 6--4 suggested

Sets time step for zone portion of simulation to 15 minutes; HVAC may run at time steps of less than 15 minutes to insure the stability of the system response (adaptive time step discussed in future lecture)

14

Solution Algorithm User has ability to control the details of

the simulation algorithm 

Options include standard heat transfer only, heat and mass transfer, and detailed (layer-by-layer) heat and mass transfer

SOLUTION ALGORITHM, \memo Determines which Heat Balance Algorithm will be used \unique-object A1 ; \field Solution Algorithm \required-field \type choice \key CTF—Conduction Transfer Functions (heat transfer only) \key MTF—Moisture Transfer Functions (detailed heat+mass) \key EMPD—Effective Moisture Penetration Depth (heat+mass) \default CTF

Note that requesting heat and mass transfer simulations can significantly increase execution time 15

Inside Convection Algorithm User may selection the inside

convection correlation from following options: 

Simple—constant natural convection



Detailed—variable natural convection



CeilingDiffuser—ACH-based correlation



TrombeWall—closed rectangular cavity

from ASHRAE from research

16

Inside Convection Algorithm (cont’d)  ASHRAE Simple Correlation for Interior

Convection  

  

Cool floor or warm ceiling: hconv = 0.948 W/m2-K Tilted surface, reduced: hconv = 2.281 W/m2-K

where reduced means a surface tilted in such a way as to mimic the poorer conditions for natural convection as in the cool floor/warm ceiling situation

Vertical surface: hconv = 3.076 W/m2-K Warm floor or cool ceiling: hconv = 4.040 W/m2-K Tilted surface, enhanced: hconv = 3.870 W/m2-K

where enhanced means a surface tilted in such a way as to mimic the better conditions for natural convection as in the warm floor/cool ceiling situation

17

Inside Convection Algorithm (cont’d)  ASHRAE Detailed Correlation for Interior

Convection

(

1.81 3 Tsurf − Tair



Reduced convection:

hconv =



Vertical surface:

hconv = 1.31 3 Tsurf − Tair



Enhanced convection: hconv =

1.382 + cos ( φsurf

(

(

)

)

)

9.482 3 Tsurf − Tair 7.283 − cos ( φsurf

)

)

where φsurf is the tilt of the surface (φsurf=0 for roof, =90 for vertical wall, =180 for floor)

18

Inside Convection Algorithm (cont’d)  Ceiling Diffuser Correlation

(

)

(

)

(

)



Floor:

hconv = 3.873 + 0.082 ACH0.98



Wall:

hconv = 1.208 + 1.012 ACH0.604



Ceiling: hconv = 2.234 + 4.099 ACH0.503

where ACH is the air changes per hour of the HVAC system 19

Outside Convection Algorithm  User may selection the outside convection

correlation from following options: 

Simple—constant natural convection

2 wind

hconv = Drough + Erough Vwind + Frough V

where D, E, and F vary with surface roughness 

Detailed—variable natural convection

hconv = hnatural + A surf B rough Vwind

where A incorporates surface and wind direction factors while B takes roughness into account and hnatural is identical to the natural convection correlation for the detailed inside convection algorithm 20

ConvectionCoefficients Allows user to set interior and/or

exterior convection coefficients 

Could be used for comparison to other programs or to determine influence of convection coefficients on simulation

ConvectionCoefficients, A1, \field SurfaceName A2, \field Convection Type #1 (either “Interior” or “Exterior”) A3, \field Convection Value Type #1 (either “Value” or “Schedule”) N1, \field Convection value #1 (W/m2-K, only used if A3 is Value) A4, \field Convection Schedule #1 (only used if A3 is Schedule) A5, \field Convection Type #2 (either “Interior” or “Exterior”) A6, \field Convection Value Type #2 (either “Value” or “Schedule”) N2, \field Convection value #2 (W/m2-K, only used if A3 is Value) A7; \field Convection Schedule #2 (only used if A3 is Schedule)

Two per surface to allow specification of both interior and exterior 21

Shadowing Calculation EnergyPlus does shadowing calculation

for periods of time and assumes that the shadow casting over this time period is the same each day User can control how often this is done through Shadowing Calculation input  

Can force EnergyPlus to do this every day Shorter shadowing periods result in longer run times for EnergyPlus

SHADOWING CALCULATIONS, N1 ; \field Shadowing period length in days (0 will use E+ default)

22

Airflow Model This parameter is only needed if the

user is trying to do detailed airflow studies using the EnergyPlus link to COMIS This statement tells EnergyPlus to do the COMIS simulation but much more input data is required (see next lecture) Airflow Model, COMIS; !- Airflow model type (COMIS or Simple, default is Simple) 23

Summary  Zone Thermostat input allows control of the

air temperature within individual zones— control setpoint can change on an hourly basis  Purchased Air can be used as a simple HVAC system when doing initial studies or trying to determine the size of the air handling system  User has the option to control various details of the simulation such as time step, convection algorithms, shading calculations, and air flow modeling 24

Lecture 11: Air Movement in Buildings


Importance of this Lecture to the Simulation of Buildings  Air is critical to sustaining life and also to the thermal

environment inside a building (comfort)  While a zone is defined by a common air mass at a particular temperature, air is not static within a building   

Unintended flow into/out of the building Purposeful flow into/out of the building Exchange between interior spaces

 Air movement may result in energy transfer from one

area to another and thus has an energy impact on the zone and/or building  Understanding the energy impact of air movement is critical to our understanding of how much energy is required to maintain thermally comfortable conditions within a space

2






Define air movement between interior spaces Approximate the effect of ventilating a building (naturally or mechanically) Perform detailed air movement calculations using the EnergyPlus link to COMIS

3

Keywords Covered in this Lecture Mixing Cross Mixing Ventilation COMIS Input Syntax

4

Mixing  Used to move air from one zone to another  Only has an impact on the receiving zone—

user must account for energy impact on source zone through Mixing, Infiltration, etc.

 Can be used to set-up multiple air flow paths

or a “circular” path between more than two zones

 User must specify flow rates and schedule

5

Mixing (cont’d) IDD Description: MIXING, A1 , \field A2 , \field N1 , \field A3 , \field N2 ; \field

Zone Name SCHEDULE Name Design Level of Air Flow in m3/s Source Zone Name Delta Temperature in degrees Celsius “Delta Temperature” controls when mixing air from the source zone is sent to receiving zone; if positive, the temperature of zone from which air is drawn must be ∆T warmer than receiving zone air or no mixing occurs; if negative, the temperature of source zone must be ∆T cooler than receiving zone air or no mixing occurs; if ∆T is zero, mixing occurs regardless of the relative zone temperatures 6

Cross Mixing  Used to exchange equal amount of air

between two zones  Has an (equal) energy impact on both zones  Only needs to be defined once for one of the two zones  Only one cross mixing statement per zone  If mixing occurs with more than one zone, must use Mixing  User must specify flow rates and schedule 7

Cross Mixing (cont’d) IDD Description: CROSS MIXING, A1 , \field Zone Name A2 , \field SCHEDULE Name N1 , \field Design Level of Air Flow in m3/s A3 , \field Source Zone Name N2 ; \field Delta Temperature in degrees Celsius Delta Temperature controls when mixing air from the source zone is sent to the receiving zone.; if positive, the temperature of zone from which air is being drawn (“source zone”) must be ∆T warmer than the zone air or no mixing occurs; if zero, mixing occurs regardless of the relative air temperatures; negative values for “Delta Temperature” are not permitted 8

Mixing and Cross Mixing Examples Zone 1

Zone 3

OK Zone 1

Zone 2

mixing Zone 3

OK Zone 2

Zone 1 cross mixing

mixing

mixing

mixing

mixing

OK

Zone 4

Zone 4

Zone 3

Zone 1 cross mixing Zone 3

Zone 2 cross mixing Zone 4

Zone 2

Illegal

9

Ventilation (Simple)  Intent is to allow simple mechanical

ventilation without specifying an HVAC system or natural ventilation  Amount of ventilation determined by user defined design flow rate, schedule, and equation similar to infiltration (allows for variation based on temperature difference and wind speed)  Type and control of ventilation determined by ventilation specific parameters 10

Ventilation (Simple, cont’d)  Control Parameters:  Minimum Temperature: indoor (zone) air temperature below which ventilation is shut off  Delta Temperature: temperature differential between inside (zone) and outside air below which ventilation is shut off (negative values allowed)  Advantage: can take effect of natural or simple

forced ventilation into account without a lot of input  Disadvantage: user must define the air flow rate (will not figure out how much air flow there will be)  Use COMIS for more serious studies of air movement within the building and between inside and outside 11

Ventilation (Simple, cont’d) Example from an IDF file: VENTILATION, !- Ventilation is specified as a design level which is modified !- by a schedule fraction, temperature difference and wind speed: !- Ventilation = Vdesign * Fschedule * !(A + B*|Tzone-Todb| + C*WindSpd + D * WindSpd**2) West Wing, !- Zone Name CONSTANT, !- SCHEDULE Name (Fschedule in Equation) 0.12, !- Design Volume Flow Rate in m3/s (Vdesign in Equation) 0.0, !- Delta Temperature in degrees C Natural, !- Ventilation Type (Natural | Intake | Exhaust) 0.0, !- Fan Pressure Rise in Pa 0.0, !- Fan Total Efficiency 1.0, !- Constant Term Coefficient (“A” in Equation) 0.0, !- Temperature Term Coefficient (“B” in Equation) 0.03, !- Velocity Term Coefficient (“C” in Equation) 0.0; !- Velocity Squared Term Coefficient (“D” in Equation)

could be used for stack ventilation

could be used for cross ventilation

12

Ventilation (Simple, cont’d)  A few thoughts on how to get the design flow rate for natural

ventilation… 



ACH: consider how many air changes per hour you might expect for natural ventilation (somewhere between infiltration and fan driven flow, probably closer to infiltration) Window area and velocity: area times velocity is volumetric flow rate  Determine window opening area (not necessarily the same as window area—depends on window type)  Multiply by some “standard” velocity (you will use the velocity coefficients so consider 1.0m/s)  Reduce this number to account for the fact that the velocity of air at the window will not be the same as the velocity of the air at the weather station and the fact that the air must go through the building



Adjust the temperature and wind speed parameters in the ventilation input to account for potential variations due to stack effect and/or wind effect on cross ventilation (can only estimate this without more detailed simulations) 13

COMIS Multizone Airflow  COMIS ⇒ Conjunction Of Multizone Infiltration

Specialists  COMIS model incorporated into EnergyPlus  Multizone airflow driven by external wind and stack effect  Does not model HVAC system impact  Computes infiltration and interzone flows which are passed to the thermal simulation  See Input Output Reference - Airflow

14

Overview of the COMIS/EnergyPlus Link  COMIS was developed in 1994 as a stand-alone multizone air

flow program with its own input and output processors. In the COMIS/EnergyPlus link, COMIS is called each time step by the EnergyPlus program. Using inside and outside temperatures and the wind pressure distribution at the beginning of a time step, COMIS calculates air flows through cracks and large openings (such as open windows) between outside and inside and from zone to zone. These are then used by the EnergyPlus thermal calculation to determine surface temperatures and zone air temperatures for that time step (which are then used in the next time step to calculate new air flow values, and so on)

15

The COMIS Input Objects  Airflow Model  COMIS Simulation  COMIS Zone Data  COMIS Surface Data  COMIS Standard Conditions for Crack Data  COMIS Air Flow:Crack  COMIS Air Flow:Opening  COMIS Site Wind Conditions  COMIS External Node  COMIS CP Array  COMIS CP Values

16

Input Object Description  COMIS Simulation defines basic run parameters for the air

flow calculation and specifies whether wind pressure coefficients are input by the user or, for rectangular buildings, calculated by the program (New Feature for Version 1.1.1).  COMIS Zone Data object specifies the ventilation control that applies to all of the openable exterior windows and doors in the corresponding thermal zone.  COMIS Surface Data indicates whether a heat transfer surface (wall, window, etc.) has a crack or opening and references a COMIS Air Flow:Crack or COMIS Air Flow:Opening object that gives the air flow characteristics of that crack or opening. COMIS Surface Data can also be used to specify individual ventilation control for openable exterior windows and doors.

17

Input Object Description (Cont.)  COMIS Standard Conditions for Crack Data is

used to normalize crack information that is based on measurements of crack air flow.  If wind pressure coefficients are input by the user, COMIS Surface Data also has an associated COMIS External Node, that, via the COMIS Site Wind Conditions, COMIS CP Array and COMIS CP Values objects, gives the wind pressure distribution vs. wind direction for that node and, implicitly, for the cracks and openings in the exterior surfaces associated with that node.

18

Relationship Among COMIS Objects Regular EnergyPlus Objects

COMIS Objects COMIS Simulation COMIS Site Wind Conditions COMIS Standard Conditions for Crack Data

Surface:HeatTransfer or Surface:HeatTransfer:Sub

Zone

COMIS Surface Data

COMIS External Node

COMIS Air Flow:Crack or COMIS Air Flow:Opening

COMIS CP Values

COMIS Zone Data

COMIS CP Array

Schedule (of venting temperatures)

19

What COMIS/EnergyPlus Can Do  Air flow through cracks in exterior or interzone surfaces  Air flow through cracks around windows and doors  Natural ventilation, i.e., air flow through open (or partially open)     

exterior windows and doors Control of natural ventilation based on inside/outside temperature or enthalpy difference Modulation of natural ventilation to prevent large temperature swings Interzone air flow, i.e., air flow through open interzone windows and doors, and through cracks in interzone surfaces Account for how air flow depends on buoyancy effects and wind pressure Account for how wind pressure depends on wind speed, wind direction and surface orientation

20

What COMIS/EnergyPlus Cannot Do  Account for the effect of supply-air and/or return-air flows in a

zone when an HVAC air system is present and is operating. This means that the COMIS air flow simulation will give reliable answers only if there is no HVAC system, the HVAC system is off, or the HVAC system is hydronic. Air flow through cracks around windows and doors.

 Air circulation and/or air temperature stratification within a

thermal zone. For example, you should not try to divide a high space, such as an atrium, into subzones separated by artificial horizontal surfaces that have cracks or openings with the expectation that COMIS/EnergyPlus will give you a realistic temperature in each subzone and/or a realistic air flow between subzones.

21

What COMIS/EnergyPlus Cannot Do (Cont.)  Bi-directional flow through large horizontal openings.

See discussion below under COMIS Air Flow:Opening.  Flow through ducts or other elements of an HVAC air system.  Pollutant transport. There are some pollutant-related inputs but they are not used.  Air-flow networks that are not connected. This means you cannot model air flow in two or more separate groups of zones.

22

Simple COMIS Air Flow Network ExternalNode-1 Window-2

Window-1

Zone-1

Door-12

Zone-2 ExternalNode-2 Door-23 Window-3

Zone-3

23

Illegal COMIS Air Flow Network ExternalNode-1 Window-1

Window-2

Zone-2

Zone-1 Door-23 Window-4

ExternalNode-2 Window-3

Zone-3

ExternalNode-3 24

Correcting the Illegal COMIS Air Flow Network  The previous slide shows an Air-flow network that is

illegal in COMIS because there are two separate groups of zones with air flow (one group is Zone-2 plus Zone-3 and the other is Zone-1). To make this legal a link (a crack or opening) between Zone-1 and Zone-2 would have to be added or the zones in one of the groups would have to be “turned off” as COMIS zones.

25

New COMIS Feature Version 1.1.1 Release  For rectangular buildings EnergyPlus will

automatically calculate surface-averaged Cp values for the walls and roof of the building if, in COMIS Simulation, you specify Wind Pressure Coefficients = SURFACE-AVERAGE CALCULATION. In this case you do not have to enter any COMIS CP Values objects.  If not calculated by program, Cp values can be obtained from wind tunnel measurements, CFD calculations, or from published values for different building shapes.

26

COMIS Input AIRFLOW MODEL, COMIS; !- AirFlowModelValue COMIS SIMULATION, VENT, !- Ventilation simulation control NO POL, !- Pollution simulation control NO CONC, !- Concentration simulation control 1.00, !- Under-relaxation factor {dimensionless} 1.0E-06, !- Absolute flow tolerance {kg/s} 1.0E-04, !- Relative flow tolerance {dimensionless} 1.0E-04, !- Error estimate for total flow per zone {kg/s} 1, !- Start number of iterations 1.0E-04, !- Limit for laminar flow approximation {Pa} 1, !- Flag for using old pressures 0, !- Flag for pressure initiation 500, !- Maximum number of iterations 10.0, !- Reference height for recorded wind data {m} 0.14, !- Wind velocity profile exponent {dimensionless} Every 30 Degrees; !- COMIS CP ARRAY Name

27

COMIS Input (Cont.) COMIS SITE WIND CONDITIONS, 0.0, !- Wind direction {deg} 0.20, !- Plan area density {dimensionless} 0.18, !- Exponent of Wind velocity profile {dimensionless} 0.0; !- Surrounding building height {m} COMIS SITE WIND CONDITIONS, 180.0, !- Wind direction {deg} 0.20, !- Plan area density {dimensionless} 0.32, !- Exponent of Wind velocity profile {dimensionless} 15.0; !- Surrounding building height {m} COMIS EXTERNAL NODE, NFacade, !- Name 1.0; !- Outside Pollutant Concentration Factor {dimensionless} . . . COMIS EXTERNAL NODE, WFacade, !- Name 1.0; !- Outside Pollutant Concentration Factor {dimensionless} 28

COMIS Input (Cont.) COMIS STANDARD CONDITIONS FOR CRACK DATA, 20.0, !- Standard temperature for crack data {C} 101.32, !- Standard barometric pressure for crack data {kPa} 5.0; !- Standard humidity ratio for crack data {g/kg} COMIS AIR FLOW:CRACK, CR-1, !- Name 0.01, !- Air mass flow coefficient {kg/s} 0.667, !- Air mass flow exponent {dimensionless} 1.0, !- Crack length {m} 0.0, !- Pollutant #1 Filter Efficiency {dimensionless} 0.0, !- Pollutant #2 Filter Efficiency {dimensionless} 0.0; !- Pollutant #3 Filter Efficiency {dimensionless}

29

COMIS Input (Cont.) COMIS AIR FLOW:OPENING, WiOpen1, !- Name 0.001, !- Air Mass Flow Coefficient When Window or Door Is Closed {kg/s-m} 0.667, !- Air Mass Flow Exponent When Window or Door Is Closed {dimensionless} 1, !- Type of large vertical opening (LVO) 0.0, !- Extra crack length for LVO type 1 with multiple openable pa {m} 2, !- Number of Opening Factor Values 0.0, !- Opening factor #1 {dimensionless} 0.5, !- Discharge coefficient for opening factor #1 {dimensionless} 0.0, !- Width factor for opening factor #1 {dimensionless} 1.0, !- Height factor for opening factor #1 {dimensionless} 0.0, !- Start height factor for opening factor #1 {dimensionless} 1.0, !- Opening factor #2 {dimensionless} 0.6, !- Discharge coefficient for Opening factor #2 {dimensionless} 1.0, !- Width factor for for Opening factor #2 {dimensionless} 1.0, !- Height factor for for Opening factor #2 {dimensionless} 0.0, !- Start height factor for for Opening factor #2 {dimensionless} 0, !- Opening factor #3 {dimensionless} 0, !- Discharge coefficient for for Opening factor #3 {dimensionless} 0, !- Width factor for for for Opening factor #3 {dimensionless} 0, !- Height factor for for for Opening factor #3 {dimensionless} 0, !- Start height factor for for for Opening factor #3 {dimensionless} . . .

30

COMIS Input (Cont.) COMIS ZONE DATA, WEST_ZONE, !- Name of Associated Thermal Zone WindowVentSched, !- Vent Temperature Schedule Temperature, !- Ventilation Control Mode 0.3, !- Limit Value on Multiplier for Modulating Venting Open Factor {dimensionless} 5.0, !- Lower Value on Inside/Outside Temperature Difference for Mo {deltaC} 10.0, !- Upper Value on Inside/Outside Temperature Difference for Mo {deltaC} 0.0, !- Lower Value on Inside/Outside Enthalpy Difference for Modul {J/kg} 300000.0, !- Upper Value on Inside/Outside Enthalpy Difference for Modul {J/kg} Optional Venting Schedule; COMIS SURFACE DATA, Surface_1, !- Name of Associated EnergyPlus Surface CR-1, !- Air Flow Crack or Opening Type SFacade, !- External Node Name 1; !- Crack Actual Value or Window Open Factor for Ventilation {dimensionless} COMIS SURFACE DATA, Window1, !- Name of Associated EnergyPlus Surface WiOpen1, !- Air Flow Crack or Opening Type SFacade, !- External Node Name 0.5; !- Crack Actual Value or Window Open Factor for Ventilation {dimensionless}

31

COMIS Input (Cont.) COMIS Cp ARRAY, Every 30 Degrees, !- Name 10.0, !- Reference height for CP data {m} 0, !- Wind direction #1 {deg} 30, !- Wind direction #2 {deg} . 270, !- Wind direction #10 {deg} 300, !- Wind direction #11 {deg} 330; !- Wind direction #12 {deg} COMIS Cp VALUES, Every 30 Degrees, !- COMIS CP ARRAY Name NFacade, !- External Node Name 0.60, !- Cp value #1 {dimensionless} 0.48, !- Cp value #2 {dimensionless} 0.04, !- Cp value #3 {dimensionless} -0.56, !- Cp value #4 {dimensionless} -0.56, !- Cp value #5 {dimensionless} -0.42, !- Cp value #6 {dimensionless} -0.37, !- Cp value #7 {dimensionless} -0.42, !- Cp value #8 {dimensionless} -0.56, !- Cp value #9 {dimensionless} -0.56, !- Cp value #10 {dimensionless} 0.04, !- Cp value #11 {dimensionless} 0.48; !- Cp value #12 {dimensionless}

32

Ventilation Control Mode 

Ventilation Control M ode 









(4 types of natural ventilation control)

Tout = outside air temperature Tzone = previous time step’s zone air temperature Tset = Vent Temperature Schedule value Hzone = specific enthalpy of zone air Hout = specific enthalpy of outside air Temperature: The windows/doors are opened if Tzone > Tout and Tzone > Tset and Venting Schedule allows venting. Enthalpic: The windows/doors are opened if Hzone > Hout and Tzone > Tset and Venting Schedule allows venting. Constant: Whenever Venting Schedule allows venting, the windows/doors are open, independent of indoor or outdoor conditions. NoVent: The windows/doors are closed at all times independent of indoor or outdoor conditions. Venting Schedule is ignored in this case. 33

Ventilation Schedules 

Field: Vent Temperature Schedule 



The name of a schedule of zone-air temperature set points that controls opening of a window/door to provide natural ventilation. This schedule consists of weeks and days, with the days containing the ventilation temperature setting in ºC for each hour of the day. This ventilation temperature is the temperature above which the window/door will be opened if the conditions described under the following Ventilation Control Mode are met. [This opening control logic does not exist in the original COMIS program.]

Field: Venting Schedule 

The name of a schedule that specifies when venting through this window/door is available. A zero schedule value means venting is not allowed. A value greater than zero means venting can occur if other venting control conditions (specified by Ventilation Control Mode and Vent Temperature Schedule) are satisfied. This schedule should not be confused with Vent Temperature Schedule.

34

Summary Air movement between spaces in

EnergyPlus can either rely on userdefined quantities or more detailed calculations Simple modeling statements: mixing, cross mixing, and ventilation COMIS link provides more detailed analysis of interzone air flow as well as more sophisticated calculation of infiltration

35

Lecture 12: Building Technology and Strategies for Sustainability


Importance of this Lecture to the Simulation of Buildings  Energy consumption of buildings (heating,

cooling, and lights) is a significant fraction of energy consumption worldwide  Many energy sources are finite so we must slow down energy consumption as much as possible  Simulation can help reduce energy consumption by modeling various strategies before they are built thus minimizing energy costs  Knowledge of various techniques for “sustainable design” and what can be simulated is crucial

2

Purpose of this Lecture Gain an understanding of: 





Some basic strategies for reducing the energy cost of buildings Various technology solutions that are currently available A few “green” capabilities of EnergyPlus

3

General Strategies for Reducing Building Heating and Cooling  Non-mechanical system approach 



Should always try to minimize heating and cooling requirements first Mechanical system efficiency important also

 Building Envelope: Insulation and/or Isolation  Solar Strategies (Passive Heating)  Alternate Cooling Strategies

4

Building Envelope: Insulation and/or Isolation  Goal: Attempt to minimize the adverse effects

of the environment on a building  

Note: effect of environment is always changing Note: in some cases (e.g., temperate/mild climates and high internally loaded buildings), we may want to maximize impact of environment because it is beneficial (Climate Specific Strategies)

 Adjust volume to exterior area ratio  Volume/living space desirable (maximize volume)  Minimizing exterior surface area (usually) since it affects conduction, convection, and radiation 5

Building Envelope: Change Wall Construction  Reduce conduction by adding insulation  

Conduction (q=A∆T/R)increase in R decreases q Note differences in R-values of various exterior surfaces and their relative areas

 Windows vs. walls: windows generally have a lower R-value  Walls vs. roofs: building shape determines where to focus attention



Consider the possibility of movable insulation for various surfaces

 Potentially reduce conduction by adding thermal mass 





“Interior” internal mass damps various short term effects, reducing or shifting conditioning needs “Exterior thermal mass delays impact of exterior temperature swings, may send some/much of effect back to exterior side Thermal mass discussed in more detail later in this lecture 6

Building Envelope: Change Exterior Boundary Conditions  Create a local “micro-climate”  Air vs. ground temperature  Ground can be a thermal mass and insulator  Air temperature changes more extreme (harm or help?)  Modification of air temperature using site water resources (evaporative cooling to reduce local air temperature)  Wind exposure  Use of vegetation as wind breaks in winter (evergreens on north side—location specific)  Allow air movement for cooling?  Note surroundings and impact on air movement around building  Surface properties 7

Solar Radiation: Light and Heat  General concepts 



 

Use solar energy when heating required, avoid it when cooling is required Sun angles (particularly altitude) can vary with time of yearthis can work to our advantage Solar adds heat and light, but only during the day Orientation of openings (windows) critical to the success of the design; in general:  Maximize southern exposure  Minimize east/west exposure 8

Solar Radiation: Light and Heat (cont’d) “Passive solar” increasingly important in

design 



A definition: “a system that collects, stores, and redistributes solar energy without the use of fans, pumps, or complex controllers” (Lechner) Lower first costs than active solar systems because they are part of the building rather than an additional syste 9

Solar Radiation: Light and Heat (cont’d)  Using Direct Solar Gain (Windows)  Utilize the “greenhouse effect” of windows which allow solar radiation to be transmitted but block most thermal radiation  Benefit is maximized with south facing windows  Low winter sun more directly impacts this direction  High summer sun has little effect on south windows, can be easily shaded



Potential for overheating during the day and underheating at night  Thermal mass (interior) helps reduce this effect  Need to exercise caution about thermal mass color and location relative to insulators such as carpet, furniture, etc.



Direct gain easy to provide but there are limitsincreasing windows to increase gain also increases heat loss through windows (at night) or heat gain when undesirable (in summer)

10

Solar Radiation: Systems  Trombe Wall Systems (more details later in

this lecture)

 Sunspaces (more details later in this lecture)  Transpired Solar Collector    

Perforated metal wall covering Solar energy heats up wall Fan assists in drawing air through panels Panels reject heat to air, heating the air before introduction into building 11

Solar Radiation: Shading  Attempt to block solar radiation from impacting the building

during cooling season  Devices can be:  

 

Natural or constructed Fixed or variable (trees of differing types, movable shades, etc.) Opaque or somewhat transparent Indoor or outdoor

 Categories/characteristics   

 

Overhang—panels or louvers, can be rotated Fins/wings—panel(s), slanted or rotating “Eggcrate”—reduced depth combined overhang/fin, slanted or rotating Roller shades/awnings Trees/vines—free standing, trellis, “attached” 12

Solar Radiation: General Shading Guidelines Exterior shading more efficient, but weather can take its toll on mechanized variable systems that are outdoors  South windows 

  



East/west windows   



 

Little shading required Desirable and even diffuse daylight Fins typically enough, if needed at all

Skylights can be problematic   



Difficult to shade due to low altitude angles Fins (slanted) more effective or eggcrates Trees best on the east, west, southeast, and southwest (northern hemisphere)

North windows 



Easiest to shade, overhangs very effective Fins may be needed for early morning, late afternoon Trees typically not much help to the south

Potential for leaks is greater Solar/light gain maximized at wrong time of year (summer) Can be more difficult to shade

Other orientations may require combination solutions

13

Alternate Cooling Techniques: Air Movement  Ventilation  Comfort ventilation: increase comfort by increasing air flow rates with the building  Night purge ventilation: ventilate (naturally or mechanically) at night when the outside air temperature is presumably cooler than inside  Technology  Windows (various types of openings)  Cool Towers (Down Draft Coolers)  Thermal Chimney 14

Alternate Cooling Techniques: Roof Cooling  Basic concept: block solar radiation during the day, then take

advantage of radiation to cold sky during the night (clouds will significantly decrease nighttime performance)  Roof Pond 



Simply a layer of water contained on a flat roof or containers of water Daytime operation

 Pond is covered with insulation to deflect solar heat and reduce connection to outside environment  Thermal mass of water soaks up heat from the interior space



Nighttime operation

 Pond is left uncovered to reject heat from water to outside environment  Heat is rejected via convection to surrounding air and to sky via radiation  Cycle can be reversed in winter to provide a Trombe Wall type roofing system 15

Roof Pond: Drawbacks Added cost of system and extra

maintenance Movable insulation systems are typically not very successful Concerns about leaks

16

Alternate Cooling Techniques: Roof Radiator  Similar in concept to roof pond, but replaces

water and movable insulation with a metal deck that is elevated above the roof 



Can use interior movable insulation with a “closed” deck Can be fan assisted with an “open” deck

 Can be used as a heating system in winter if

solar energy is trapped between metal deck and roof 

Hot air is then circulated to interior spaces

 Drawbacks  Added costs of roof deck  Reliability/longevity of movable insulation 17

Roof Radiator: Cooling Operation  Daytime operation  Metal panel reflects a portion of the solar radiation  Insulation blocks heat transfer to building interior  Or ventilation air reduces heat transfer from roof deck to actual roof  Nighttime operation  Roof radiates heat to sky  Roof temperature may be low enough to actually cool outside air even further 18

Earth Coupling: Direct Earth Coupling  Underground or berms  Ground temperatures can be lower than

outside air, making this a good heat sink

 Concerns about winter may require

insulation of ground and/or building surfaces in contact with ground

 Potential moisture problems

19

Earth Coupling: Indirect Earth Coupling  Buried supply air tubes  Inlet air diverted through pipes that are buried  Air is cooled by the cooler ground, providing some free cooling  Pipes must be buried significantly deep  Maintenance and moisture issues  Ground “micro-climate” change using

evaporation 

 

Cool the ground surrounding a building using evaporation Ground connected buildings Elevated buildings

20

EnergyPlus Modeling Capabilities Thermal Mass Trombe Wall Sunspaces Movable/transparent insulation

21

Thermal Mass/Energy Storage within Buildings: Theory  Storage energy (heat) within building elements

(exterior or interior) for use or release at a later time/date (analogy of a sponge or a rechargeable battery)  Building materials store heat as “internal energy”  Thermal mass a function of material properties (specific heat and density) as well as volume of material→how much thermal mass is “enough”?  Energy stored in a building material will eventually be release—either to the interior or exterior depending on placement of mass, environmental conditions, etc. 22

Thermal Mass: Examples Traditional Examples  Dense building types with very thick walls  Ice blocks from Lake Michigan More Modern Examples  “Trombe Walls”  Interior Water Walls or Containers  Phase Change Materials 23

Thermal Mass: Seasonal Effects  Cooling Season  



Dampen the effect of outside temperature variations Shift time of highest cooling loads to the night hours (offices) Absorb excessive internal gains during daytime hours (usually combined with night ventilation strategies)

 Heating Season 





Store solar energy absorbed for use during the nighttime hours when temperatures are low and the sun is not visible Avoid potential overheating problems due to excessive direct solar gains Note: thermal mass effects will not show up in a winter design day run—must look at an annual simulation with actual weather data

24

Thermal Mass: Key Terms in EnergyPlus IDF Material:Regular—specification of

specific heat and density Construction—reference to a material layer definition Surface—reference to a construction definition

25

Trombe Walls: Theory  Primarily a passive heating element used to

delay the impact of solar radiation

 Intended to cooperate with direct gain

through windows to provide heating via solar radiation during all parts of the day and night

 Most useful on south, southeast, and

southwest facades

26

Trombe Walls: System components  Thermally massive wall (brick, concrete,

stone, water) painted a dark color to absorb solar radiation

 Air gap  Wall cover (transparent glass) to allow

sun light to get through to the thermal mass and to block some of the heat loss to the outside environment

27

Open vs. Closed Trombe Walls  Open System  Similar to a mini-sunspace where the air in the gap between the cover and the wall mass is allowed to circulate to an interior space  More important if no visual link to the outside  These have fallen out of favor (in US) due to difficulty in controlling the amount of exchange between the air gap and the attached space and due to the loss of delay factor (easier to combine wall with windows); also maintenance issues 28

Open vs. Closed Trombe Walls Closed System 



Air gap between the wall mass and the cover is sealed Heat is trapped and absorbed better into the thermal mass

29

Trombe Walls: Performance  Best for heating when wall mass has both a

high storage capacity and a high thermal conductivity  High thermal conductivity increases heat gain/loss of overall wall assembly  Wall cover should be as transparent as possible but also resistive  Solar must be kept out of the Trombe wall in summer through use of:   

Shading devices Specialized transparent insulation materials Electrochromic or thermochromic glazing

30

Trombe Walls: Examples  Trombe walls are usually but not necessarily

restricted to simple flat south-facing walls (compare Zion National Park Visitor’s Center to NREL Visitor’s Center)

Photos courtesy of www.nrel.gov

31

Trombe Walls: Key Terms in EnergyPlus IDF  Material:WindowGlass—specification of window

properties  Construction—definition of wall and window constructions  Surface—specification of wall and cover (separate) with wall defined as an “interzone partition  Zone—definition of Trombe Wall air gap as a separate thermal zone 





Cover is specified as a window covering a fictitious exterior wall Trombe wall shows up in TWO zones (equal and opposite interzone partition) Zone definition must include syntax to use special Trombe wall coefficients

32

Trombe Walls: Example of Trombe wall syntax (Zone) ZONE, Lounge, 0.0, 10.0, 14.9, 0.0, 1, 1, 4.0, 0.0, TrombeWall;

!!!!!!!!!!-

Zone Zone Zone Zone Zone Zone Zone Zone Zone Zone

Name North Axis (relative to Building) X Origin {m} Y Origin {m} Z Origin {m} Type Multiplier Ceiling Height {m} Volume {m**3} Inside Convection Algorithm

33

Sunspaces and Double Skinned Buildings  Sunspaces and double skinned buildings can also be

modeled as separate zones 



 

Note that in EnergyPlus solar radiation will pass through one space and into another but that once it gets to the second zone it is assumed to be all “diffuse” Both sunspaces and double skinned buildings provide an extra buffer from the outside Sunspaces add potentially usable space For systems which exchange heat through air transport, definition of a MIXING or CROSS MIXING statement required (not very accurate)

34

Movable Insulation: Purpose  Apply insulating layer to exterior (or interior)

of building that can be scheduled for various times of day or year

 Intended to trap heat inside a building or

block heat from coming into a building during certain times

 Many applications, but in reality, most of

these are not feasible due to complexity of the systems 35

Movable Insulation: Process In EnergyPlus, movable insulation can

be applied to the interior or exterior side of a surface (but not windows) Window insulation must be specified as window blinds Exterior insulation may be transparent

36

Movable Insulation: Syntax  Insulation type: must be keyword “Interior” or

“Exterior”  Surface name: surface that insulation will be applied to (link to a surface definition within the input file)  Material name: composition/description of material layer that makes up the insulation (link to a material definition within the input file)  Schedule: when the movable insulation is applied (link to a schedule definition within the input file)

37

Movable Insulation: Example Example of IDD format and IDF: MovableInsulation, A1, \field Insulation Type ( Exterior or Interior ) A2, \field Surface Name (heat transfer surface to which insulation applied) A3, \field MaterialMovInsul- Name of the material used for movable insulation A4; \field SchedMovInsul-Schedule for movable insulation

Schedule controls if insulation is present and acts as a multiplier on the R-value of the material Material layer can be transparent if exterior insulation MovableInsulation, Exterior, Zn001:Wall001, MovableInsulationMaterial, ON; MATERIAL:REGULAR-R,MovableInsulationMaterial,Rough,2.0,0.9,0.7,0.7;

38

Summary  Careful attention to climate and building

heating and cooling needs as well as knowledge of passive strategies can help significantly reduce the amount of energy consumed to condition a building  EnergyPlus “green” building modeling capabilities:    

Thermal Mass Trombe Wall Sunspaces Movable/Transparent Insulation 39

Lecture 13: HVAC Loops, Nodes, and Connections


Importance of this Lecture to the Simulation of Buildings  So far, we have discussed how much heating or

cooling energy is required to maintain a particular thermal environment inside a building  Something must meet these heating and cooling loads in order for the thermal comfort goals to be metHVAC system  “System” or secondary system meets thermal loads of the zones  Primary system (central plant) produces or converts energy for use by the secondary system  Primary and secondary systems are not perfectly efficient and will impact the energy consumption of a buildingthus, we need to simulate these as well

2




Structure of an HVAC (primary and secondary) system How an HVAC system is described within EnergyPlus (big picture)

3

Keywords Covered in this Lecture Branch Branch List Connector List Splitter and Zone Splitter Mixer and Zone Mixer Node List

4

HVAC Input Overview  Hierarchical set of objects      

Loops (air, chilled & hot water, condenser) Supply and demand sides Topology of sides: branches, splitters, and mixers Branches: components along a single duct or pipe Components: specific pieces of equipment Nodes: store components’ inlet & outlet conditions

5

HVAC Input Overview (cont’d) Multiple systems or zone components

can serve each zone EnergyPlus HVAC simulation attempts to satisfy the conflicting demands of: 

Input simplicity & usability



Input flexibility & generality



Simulation robustness

6

EnergyPlus HVAC Loop Overview Loop Types: 

Air Loop



Zone Equipment Loop



Plant Loop Supply Side



Plant Loop Demand Side



Condenser Loop Supply Side



Condenser Loop Demand Side

7

Air Loop Air side of the secondary system Typically contains equipment such as a

fan, coils, mixing box, etc. Where the centralized conditioning of air takes place—before splitting off to zones, before reheat, before individual VAV dampers, etc.

8

Zone Equipment Loop Equipment that is more specific to a

particular thermal zone May include splitters and air distribution units which split up flow from the air loop Can have multiple systems serving individual zones 9

Zone Equipment Schematic Zone Supply Air Splitter

Return Air Path

Dual Duct Constant Volume (CV)

Zone Exhaust Branch (Opt.)

Dual Duct VAV

Air Distribution Unit

Zone 1

Select One

Low Temp Radiant

Select One

High Temp Radiant/ Convective

Local Convective Units

None

Single Duct CV Reheat

Air Distribution Unit Options

Single Duct VAV: Reheat

Diagram from I nput Output Reference p. 208 (not all equipm ent types are included)

Select One

Select One

Low Temp Radiant Panels Low Temp Rad Alternatives

High Temp Radiators

Radiators

Hi Temp Rad/Conv Alternatives

Baseboards

Window AC

Fan Coil

Unit Heater/ Vent ilator

Air -Air HP

Water-Air HP & Ground Source HP

Local Conv. Unit Alternatives

10

Plant Demand Side Water side of coils, radiant systems,

etc. that require conditioned fluid to provide either heating or cooling to the zone (the “demand”) Connects to air loop or zone equipment loop through individual components Connects to plant supply side through direct fluid connection 11

Plant Supply Side  Supplies hot or cold fluid to meet the

demands of the plant demand side  Equipment may include pumps, chillers, boilers, etc.  Typically controls both flow rate (via pump) and temperature (loop setpoint)  Connects directly to plant demand side  Connected indirectly to condenser demand side through components 12

Condenser Supply and Demand Sides  Analogous to plant supply and demand sides  Condenser demand receives heat rejection from plant

supply side equipment  Condenser supply side tries to supply the conditioned fluid by rejecting heat to external environment  Condenser supply side may only be connected to condenser demand side  Condenser demand side also connected indirectly to plant supply side through components and may also be connected to air loop and zone equipment loop through components

13

EnergyPlus HVAC Loop Interaction Building Systems Simulation Manager Zone

Zone

Simulate Building

Conditions Predictor

Conditions

Systems

Corrector

Plant Loop Demand

Supply

Air Loop Main Air Handler

Condenser Loop Coils, Baseb., etc.

Plant Equip.

Demand

Supply

Cond., Coils, etc.

Towers, Wells, etc.

Zones & Equip.

14

EnergyPlus HVAC Loop Structure General rules on EnergyPlus loop

structure:  





Maximum of one “parallel” section per loop Maximum of one splitter and one mixer per loop Equipment may be arranged in series on any particular branch Only one bypass (in a parallel section) per loop 15

Loops, Branches, Components, and Nodes Comp

Branches

Components

… Splitter

Loop

Comp

Comp

Comp

…

…

…

…

Comp

…

Mixer Comp

…

Nodes

16

EnergyPlus Branches  Definition: a collection of components

connected in series  Branches are linked together through connection components (splitters and mixers)  A loop may consist of a single branch or multiple branches  Input keywords:  

Branch Branch List 17

Branch Lists components and nodes associated

with the components on the branch Only used for air branches Example: BRANCH, Zone 3 Reheat Branch, 0, COIL:Water:SimpleHeating, Reheat Coil Zone 3, Zone 3 Reheat Water In Node, Zone 3 Reheat Water Out Node, ACTIVE;

!!!!!!!-

Branch Name Maximum Branch Flow Rate {m3/s} Comp1 Type Comp1 Name Comp1 Inlet Node Name Comp1 Outlet Node Name Comp1 Branch Control Type

Options are: ACTIVE, PASSIVE, and BYPASS; determines which component tried to control the flow on the branch

Repeated for each component on the branch

18

Branch List Used by loops to determine which

branches are a part of the loop Example: BRANCH LIST, Condenser Demand Side Branches, Condenser Demand Inlet Branch, Little Chiller Condenser Branch, Big Chiller Condenser Branch, Condenser Demand Bypass Branch, Condenser Demand Outlet Branch;

!!!!!!-

Branch Branch Branch Branch Branch Branch

List Name Name Name Name Name

Name 1 2 3 4 5

19

Connector List Used by loops to determine which

connectors (splitters and mixers) are a part of the loop Maximum of one each allowed (two total) Connector type must be SPLITTER or MIXER CONNECTOR LIST, Condenser Demand Side Connectors, SPLITTER, Condenser Demand Splitter, MIXER, Condenser Demand Mixer;

!!!!!-

Connector List Name Type of Connector 1 Name of Connector 1 Type of Connector 2 Name of Connector 2

20

Splitter Used to distribute fluid flow into various

parallel legs in a loop Single inlet branch One or more outlet branches (50 max) SPLITTER, CW Loop Splitter, CW Pump Branch, Little Chiller Branch, Big Chiller Branch, Purchased Cooling Branch, Supply Bypass Branch;

!!!!!!-

SplitterName Inlet Branch Name Outlet Branch Name Outlet Branch Name Outlet Branch Name Outlet Branch Name

1 2 3 4 21

Zone Splitter Same as Splitter except used for air

loops Single inlet branch One or more outlet branches (50 max) ZONE SPLITTER, Zone Supply Air Splitter, Zone Equipment Inlet Node, Zone 1 Reheat Air Inlet Node, Zone 2 Reheat Air Inlet Node, Zone 3 Reheat Air Inlet Node;

!!!!!-

Splitter Name Inlet_Node Outlet Node 1 Outlet Node 2 Outlet Node 3

22

Mixer Used to combine or mix several parallel

branches back together again Opposite of a Splitter One outlet, one to 50 inlet branches MIXER, Heating Heating Heating Heating

Supply Mixer, Supply Outlet Branch, Purchased Hot Water Branch, Supply Bypass Branch;

!!!!-

MixerName Outlet Branch Name Inlet Branch Name 1 Inlet Branch Name 2

23

Zone Mixer Same as Mixer except used for air loops Single outlet branch One or more inlet branches (50 max) ZONE MIXER, Zone Return Air Mixer, Return Air Mixer Outlet, Zone 1 Outlet Node, Zone 2 Outlet Node, Zone 3 Outlet Node;

!!!!!-

Mixer Name Outlet Node Inlet Node 1 Inlet Node 2 Inlet Node 3

24

EnergyPlus Components Simple Components  input; initialize; calculate; report Compound Components  assembled from multiple simple components  simulated sequentially with overall control Complex Components  component may be a system 25

EnergyPlus Nodes  A node is the point at

which a component, such as a source or a load, is connected to the system.

CHWR

Chiller

CHWS

Nodes

Load CHWR

CHWS Nodes

26

EnergyPlus Nodes (cont’d) Nodes connect components in HVAC

network Store network state data 

temperature, humidity, flow rate, pressure (air only) at current barometric pressure

Also store control information: set

points Store component input and output data 27

Example Node Diagram 2

1 5

6

7

8

Return Fan

9

4

3 8

2

Mixed Air System Manager

7

MA Damper

3

10

2

12

3

4

5

6

Heat Recovery 6

11

1

13

7

Desiccant Wheel 9

8

Supply Fan 9

Zone

10

12

Splitter

10

11

Heating Coil 12

13

Cooling Coil

28

EnergyPlus Nodes (cont’d) Components have one or more pairs of

inlet/outlet nodes  

Fan: Air inlet node, Air outlet node CHW Coil: Air inlet node, Air outlet node, CHW inlet node, CHW outlet node

29

EnergyPlus Nodes (cont’d) Components read inlet node data and

write outlet node data Most components “know” nothing more than their respective input specifications and inlet/outlet node data Each zone has a single node for the zone air conditions Node data available for output reporting 30

Node List In some cases, a single node or a list of

nodes may be appropriate input Node List allows user to specify a variable length list of nodes as input Name is then referenced elsewhere in the input file NODE LIST, Zone1Inlets, !- Node List Name Zone 1 Reheat Air Outlet Node, !- Node Name 1 Zone 1 Fan Coil Outlet Node; !- Node Name 2

31

Branch and Node Details Output File *.bnd output file Details about branches, nodes, and

other elements of the flow connections Intended for use in debugging potential problems

32

BND File – Node Lists ! #Nodes, #Nodes,72 ! ,,<# Times Node Referenced After Definition> 1,ZONE 1 INLET NODE,2 2,ZONE 2 INLET NODE,2 =============================================================== Suspicious nodes have 0 references. It is normal for some nodes, however. Listing nodes with 0 references (culled from previous list): ! ,,<# Times Node Referenced After Definition> 65,ZONE 1 NODE,0 67,ZONE 2 NODE,0

33

BND File – Branch Lists ! <#Branch Lists>, #Branch Lists,7 ! ,,,, ! <#Branches on Branch List>, ! ,,, ! ,, Branch List,1,AIR LOOP BRANCHES,TYPICAL TERMINAL REHEAT 1,Air #Branches on Branch List,1 ..Branch,1,AIR LOOP MAIN BRANCH,TYPICAL TERMINAL REHEAT 1 ....Branch Inlet/Outlet Nodes,AIR LOOP INLET NODE,AIR LOOP OUTLET NODE Branch List,2,COOLING SUPPLY SIDE BRANCHES,CHILLED WATER LOOP,Plant Supply #Branches on Branch List,6 ..Branch,1,CW PUMP BRANCH,CHILLED WATER LOOP ....Branch Inlet/Outlet Nodes,CW SUPPLY INLET NODE,CW PUMP OUTLET NODE ..Branch,2,LITTLE CHILLER BRANCH,CHILLED WATER LOOP ....Branch Inlet/Outlet Nodes,LITTLE CHILLER INLET NODE,LITTLE CHILLER OUTLET NODE 34

BND File – Supply Air Paths ! <#Supply Air Paths>, #Supply Air Paths,1 ! ,, ! <#Components on Supply Air Path>, ! ,,, Supply Air Path,1,TERMREHEATSUPPLYPATH #Components on Supply Air Path,1 Component,1,ZONE SPLITTER,ZONE SUPPLY AIR SPLITTER ! <#Nodes on Supply Air Path>, ! ,, #Nodes on Supply Air Path,4 Inlet Node,1,ZONE EQUIPMENT INLET NODE Outlet Node,2,ZONE 1 INLET NODE Outlet Node,3,ZONE 2 INLET NODE Outlet Node,4,ZONE 3 INLET NODE

35

BND File – Return Air Paths ! <#Return Air Paths>, #Return Air Paths,1 ! ,, ! <#Components on Return Air Path>, ! ,,, Return Air Path,1,TERMREHEATRETURNPATH #Components on Return Air Path,1 Component,1,ZONE MIXER,ZONE RETURN AIR MIXER ! <#Nodes on Return Air Path>, ! ,, #Nodes on Return Air Path,4 Outlet Node,1,RETURN AIR MIXER OUTLET Inlet Node,2,ZONE 1 OUTLET NODE Inlet Node,3,ZONE 2 OUTLET NODE Inlet Node,4,ZONE 3 OUTLET NODE

36

BND File – Component Sets ! <#Component Sets>, #Component Sets,34 ! ,,,,,,,, Component Set,1,BRANCH,AIR LOOP MAIN BRANCH,FAN:SIMPLE:CONSTVOLUME,SUPPLY FAN 1,AIR LOOP INLET NODE,COOLING COIL AIR INLET NODE,Air Nodes Component Set,2,BRANCH,AIR LOOP MAIN BRANCH,COIL:WATER:DETAILEDFLATCOOLING,DETAILED COOLING COIL,COOLING COIL AIR INLET NODE,AIR LOOP OUTLET NODE,Air Nodes

37

BND File – Air Loops ! <#Primary Air Loops>, #Primary Air Loops,1 ! ,,<# Return Nodes>,<# Supply Nodes>,<# Zones Cooled>,<# Zones Heated>, ! ,,,, ! ,,,, ! ,,, ! ,,, ! ,,,,OA Mixed Air Outlet Node Name> Air Loop,TYPICAL TERMINAL REHEAT 1,1,1,3,0,No Return Node #1,72,RETURN AIR MIXER OUTLET,5,AIR LOOP INLET NODE Supply Node #1,71,ZONE EQUIPMENT INLET NODE,4,AIR LOOP OUTLET NODE Cooled Zone #1,RESISTIVE ZONE,1,ZONE 1 INLET NODE Cooled Zone #2,EAST ZONE,2,ZONE 2 INLET NODE Cooled Zone #3,NORTH ZONE,3,ZONE 3 INLET NODE 38

BND File – Plant Loops ! <# Plant Loops>, #Plant Loops,2 ! ,,,,,, Plant Loop,CHILLED WATER LOOP,Supply,CW SUPPLY INLET NODE,CW SUPPLY OUTLET NODE,COOLING SUPPLY SIDE BRANCHES,COOLING SUPPLY SIDE CONNECTORS Plant Loop,CHILLED WATER LOOP,Demand,CW DEMAND INLET NODE,CW DEMAND OUTLET NODE,COOLING DEMAND SIDE BRANCHES,COOLING DEMAND SIDE CONNECTORS Plant Loop,HOT WATER LOOP,Supply,HW SUPPLY INLET NODE,HW SUPPLY OUTLET NODE,HEATING SUPPLY SIDE BRANCHES,HEATING SUPPLY SIDE CONNECTORS Plant Loop,HOT WATER LOOP,Demand,HW DEMAND INLET NODE,HW DEMAND OUTLET NODE,HEATING DEMAND SIDE BRANCHES,HEATING DEMAND SIDE CONNECTORS

39

BND File – Condenser and Heat Recovery Loops ! <# Condenser Loops>, #Condenser Loops,1 ! ,,,,,, Cond Loop,CHILLED WATER CONDENSER LOOP,Supply,CONDENSER SUPPLY INLET NODE,CONDENSER SUPPLY OUTLET NODE,CONDENSER SUPPLY SIDE BRANCHES,CONDENSER SUPPLY SIDE CONNECTORS Cond Loop,CHILLED WATER CONDENSER LOOP,Demand,CONDENSER DEMAND INLET NODE,CONDENSER DEMAND OUTLET NODE,CONDENSER DEMAND SIDE BRANCHES,CONDENSER DEMAND SIDE CONNECTORS =============================================================== ! <# Heat Recovery Loops>, #Heat Recovery Loops,0 ! ,,,

40

BND File – Controlled Zones ! <# Controlled Zones>, #Controlled Zones,3 ! ,,,,,,<# Inlet Nodes>,<# Exhaust Nodes> ! ,,,,
! ,, Controlled Zone,RESISTIVE ZONE,ZONE1EQUIPMENT,,ZONE 1 NODE,ZONE 1 OUTLET NODE,1,0 Controlled Zone Inlet,1,ZONE 1 INLET NODE,ZONE 1 INLET NODE,N/A Controlled Zone,EAST ZONE,ZONE2EQUIPMENT,,ZONE 2 NODE,ZONE 2 OUTLET NODE,1,0 Controlled Zone Inlet,1,ZONE 2 INLET NODE,ZONE 2 INLET NODE,N/A Controlled Zone,NORTH ZONE,ZONE3EQUIPMENT,,ZONE 3 NODE,ZONE 3 OUTLET NODE,1,0 Controlled Zone Inlet,1,ZONE 3 INLET NODE,ZONE 3 INLET NODE,N/A

41

Examples of EnergyPlus HVAC

Diagrams with Loops, Branches, Components, and Nodes

Simplified Plant Node and Equipment Diagram Typical Plant & Condenser Loop Plant Supply Side

Cond Supply Side Loop

Pump

2 Mix -Cond 3 Splitter

Cond Pump Purchased Heating/ Cooling

Towers, Wells, Etc. Heating or Cooling Equipment

3 Mixer Cooling Tower 2 Split -Cond

Cond Demand Side Loop 43

Example System

44

Non-Conventional Cooling Options Outside Air

Supply Fan

Connect the Cooling Tower Directly to the Cooling Coil

CW Pump

CC Bypas s

Bypass

Mixed Outside Air Box

Relief Air

Cooling Tower

East Zone

North Zone

Zone Air Splitter

Return Air Mixer

Resistive Zone

Cooling Tower

Pump

Bypas s

Connect the Cooling Tower Directly to the Radiant Slab. This would limit the possibility of Condensation in the Zone or "Indoor Rain"

45

Low Intensity Radiant Floor Slab & Conventional Cooling Outside Air

Supply Fan

CW Pump

Plant Supply Side Cooling Loop

CC Plant Demand Side Cooling Loop

Bypass


Bypass

Chiller

Relief Air

Condenser Bypass

East Zone

Zone Air Splitter

Return Air Mixer

Resistive Zone

Cond Demand Side Loop Boiler Cond Pump Pump

Condenser Bypass

Plant Supply Side Heating Loop North Zone

Cooling Tower

Bypass

Cond Supply Side Loop

46

Summary  EnergyPlus uses a loop-node concept to

describe primary and secondary systems  Six main loop types:   

Air Loop and Zone Equipment Loops Plant Supply and Demand Loops Condenser Supply and Demand Loops

 Loops are constructed of branches  Branches contain components in series  Nodes exist at the beginning and ending of

each branch as well as between components 47

Lecture 14a: Introduction to Secondary Systems


Importance of this Lecture to the Simulation of Buildings Simulation is important, but

understanding what one is simulating is equally critical Lack of understanding (treating an HVAC system like a black box) can lead to errors in input

2






Different types of space conditioning systems General characteristics about how they operate and what some of their advantages/disadvantages might be Prepare for upcoming lectures on EnergyPlus system input 3

All-Air Systems: Overview  Provides all sensible and latent cooling, preheating,

and humidification required by the zone(s)  Additional cooling or humidification at the zone rare (industrial systems)  Heating is either provided by the main air stream by the central system or locally at a specific zone  Classified into single- and dual-duct categories as well as constant and variable volume categories  Conditioning depends on air mass flow rate and temperature (enthalpy) difference between supply and room air 4

Single-Duct Systems    

Main heating and cooling coils in series arrangement Ducts supply air to all terminals at a common temperature Capacity varied by varying temperature or flow rate Types of single-duct systems 

Constant Volume

 Single zone  Multiple-zone reheat  Bypass VAV



Variable Air Volume (VAV)     

Throttling Fan-powered Reheat Induction Variable diffusers

5

Dual-Duct Systems  Main heating and cooling coils in parallel  May use separate warm and cold air duct distribution systems, blending

air at the terminal device  May blend air near the main unit and have separate duct for each zone  Most vary supply temperature, limited number (around 1% of all installed systems?) vary flow rate  Types of dual-duct systems 

Single zone (“dual duct”)  Constant volume  Variable air volume  Dual conduit



Multizone

 Constant volume  Variable air volume  Three-deck multizone

6

Variable Volume vs. Variable Temperature  Variable Volume  Throttling back flow when less heating/cooling required  Reduced flow results in reduced fan energy  Potential concerns about outdoor air quantities for IAQ and humidity control  Variable Temperature  Temperature of supply air changes as thermal loading conditions change  Variation in temperature may require additional energy (or use of more outside air) 7

Advantages vs. Other System Types  Flexible: high degree of flexibility on how to

meet loads, distribute air, etc.  Low noise: most equipment kept away from occupied spaces  Control: probably the best control of both temperature and humidity can be achieved with air systems (precise control situations)  Most easily understood and popular  Indoor air quality: IAQ is part of the system (not an “afterthought”) 8

Disadvantages vs. Other System Types  Space: require additional space for air

distribution ductwork (vertically and horizontally) adds to building size in all directions

 Concerns about access to terminal devices  Requires air balancing which can be difficult

on large systems

 Perimeter heating not always available during

construction

9

Single-Zone Constant Volume  Also known as single zone

draw through system  Simplest all-air system, meets all conditioning needs of space  System can be in zone or at a remote location, with or without distribution ductwork  Little or no ductwork means low pressure drop and lower fan energy  Systems can be turned off without affecting adjacent systems 10

Multiple-Zone Reheat (Constant Volume)  Also known as terminal reheat

in some circles  Single air stream at a fixed temperature delivered to various spaces  Local supply temperature is varied by the use of a terminal reheat coil  Main duct temperature typically cooled to cold deck temperature (all year)large amount of energy consumption  When main duct air temperature varies, could have humidity problems

11

Constant Volume Bypass  Bypass replaces reheat coil  Total flow of system remains constant but flow of air

to space is varied  Excess flow is bypassed around zone and directly into return duct  Saves the energy that would be used by the reheat coil  Requires a return fan to avoid air short circuiting back into the room from the bypass; still have contact supply fan energy  Usually only used in smaller applications where humidity control is not as important 12

Variable Air Volume Systems  Objective: reduce flow rate when loads

   

  

are not as high to save fan energy (fan energy proportional to flow rate cubed) Especially effective for perimeter zones that may receive solar heating Temperature is maintain same for all zones, flow rate varied to each Flow rate bounded at lower end by a minimum air fraction Concern 1: indoor air quality—outside air may limit lower bound of VAV flow rate Concern 2: humidity—it may also limit lower bound of VAV flow rate Terminal devices used to further reduce cooling or to provide heating From maximum cooling point, VAV first throttles back flow and then adds reheat (or uses terminal device)

13

Dual-Duct Systems: Overview  Two air streams are conditioned at a central location:

one warm, one cold  Air distributed to spaces through: 



Two ducts (one warm, one cold) and mixed locally, disadvantage of two ducts (both must be sized to handle their maximum flow rate though this may be different for heating and cooling, cost, space) A single duct per zone after mixed centrally, disadvantage(?) of multiple ducts

 Tends to require more energy than a VAV system  Dual-duct can serve one or more thermal zones  May have more than one fan (dual fan—one for each

duct)

14

Dual-Duct Constant Volume  Total air flow rate remains fixed,

but volume through each duct varies with heating/cooling load  Single fan with reheat 









Similar to the terminal reheat system Reheat applied at a central location rather than at each individual zone Air is not cooled and then reheated as in terminal reheat Uses less energy than terminal reheat because some air is heated and other air is cooled Constant volume system—air flow is constant and thus fan energy is always same (high)

15

Dual-Duct Constant Volume (cont’d)  Single fan, no reheat  





Similar to a single-duct system Simply has a cooling coil bypass and is very similar to a single duct system Does not expend energy to reheat air, simply uses a mixture of return and outdoor air Less air is sent through cooling coil, may result in less dehumidification and thus moisture problems during parts of the year (spring/fall)

16

Dual-Duct Variable Air Volume (DDVAV)  Blends warm and cold air in variable

volume combinations  Flow reduced below maximum load and flows mixed at minimum flow rate (which might be limited by outside air or humidity concerns)  Can be combined with single duct VAV systems for zones that are cooling only (interior spaces)  Dual-duct terminal units can also serve as separate VAV systems (one warm, one cold) which can reduce fan energy and heating and cooling energy 17

Single Fan DDVAV  Fan sized for the “coincident peak” of the hot and

cold deck volumes  Control via two static pressure controllers (one in each deck)  Cold deck typically kept at same temperature though it may be varied  Hot deck sometimes adjusted up when temperature outside is low or when humidity is high (to force more air through the cold deck)  Some systems may use a precooling coil for the mixed or outside air 18

Dual Fan DDVAV  Volume of each fan independently controlled  Each fan sized for anticipated maximum

coincident hot or cold volume (not sum of instantaneous peaks)

 Cold deck maintained with either outside air

(free cooling) or mechanical refrigeration

 Hot deck can use return air, heating coil, or

outside air (rare, humidity concerns) to provide heating

19

Dual Conduit  Really a “dual system” configuration  Primary air (constant flow) system:    

Used to meet exterior transmission (perimeter) loads Run only during peak periods Runs without outside air (can be fairly local) Must be sized to account for action of secondary system at minimum air fraction

 Secondary air (variable volume) system:   

 

Runs year-round Serves both interior and perimeter spaces Used to meet the loads from people, lights, equipment, and solar heating Used to bring in outside (fresh) air Variation on this system mixes the two air streams using a dual duct terminal box—in this case the primary system is heating only and the secondary system must meet the entire cooling load 20

Multizone Systems: Overview Similar to a dual-duct system (though

only for more than one zone) Multizone systems share same advantages and disadvantages as dualduct systems Multizone systems can be obtained as “packaged” units (lower first costs) of up to approximately 12 zones 21

Three-Deck Multizone  Has an additional duct for 



 

“unconditioned” air This duct is in addition to the warm and cold air ducts (hence the name) Only two of the ducts unconditioned and either warm or cold used at any given time (seasonal switchover) Generally not used due to the extra initial expenses Can be mimicked by a standard dual-duct by seasonally scheduling coils 22

Summary  Single-duct systems:  Main heating and cooling coils in series arrangement  Ducts supply air to all terminals at a common temperature  Capacity varied by varying temperature or flow rate  Dual-duct systems  Main heating and cooling coils in parallel  May use separate warm and cold air duct distribution systems, blending air at the terminal device  May blend air near the main unit; separate duct for each zone  Most vary supply temperature

23

Lecture 14b: Introduction to Secondary Systems


Special Systems: Dual Air Stream System  Two interconnected all air systems (diagram)  Primary air system used for outside air  Secondary air system used to condition space  Used when there are high space gains or high

air flow rates required

 Both systems might have heating and cooling

coils

25

Special Systems: Under-floor Air Distribution (UFAD)  Also called “up air system”  Air distributed from floor rather than

overhead  Air enters space through floor registers or through furniture  Individual control and high degree of flexibility  Floor surface is also “conditioned” (pseudoradiant system) 26

Special Systems: Evaporative Cooling  Water vapor added to air stream to reduce

the dry bulb temperature

 Raises the humidity level so this tends to only

have application in drier climates

 Cooling can either be direct (of supply or

outside air stream) or indirect (return air with heat exchanger)

 Can offset cooling needs, requires water as a

resource

27

Special Systems: LowTemperature Systems  Concept: lower the supply air temperature for cooling

so that we can reduce the flow rate (less flow means less fan energy)  Typically only used in conjunction with ice storage systems  Ice can be used to produce lower supply air temperatures  Cannot produce colder air directly using chiller because lower evaporator temperatures will make chiller less efficient  Terminal units may be required to maintain a sufficient amount of air movement within the space

28

Terminal Units: Overview  Terminal unit is the last (hence terminal)

device on the air distribution system (between the duct and the conditioned space)  Two types: 



Supply outlet—register or diffuser: goal is to supply air to the space without causing drafts or excessive noise Terminal unit: controls the quantity and temperature of the supply air (by further conditioning the air) 29

Constant Volume Reheat Terminal Units Used mainly in terminal reheat systems Reheat coil adds heat to avoid

overcooling (supply air temperature generally cooled down to around 13°C first) Can lead to excessive energy consumption (frowned upon by ASHRAE Standard 90.1) 30

Variable Air Volume Terminal Units Terminal unit reduces the flow rate in

an attempt to provide only enough cooling to match the actual cooling load Care must be taken to avoid too much flow in areas close to the air handler

31

Throttling Units  Throttling Unit Without Reheat  Air flow rate can be throttled down to meet the cooling load  Sometimes flow can be completely shutoff (air quality concerns)  Concerns about noise from throttling (typically have some sort of sound attenuation)  Throttling Unit With Reheat  Air flow rate can be throttled down to some minimum  Below the minimum, reheat energy would be required  Can also be used in cases where there are actual heating loads  Flow rate reduced first, then reheat added  Some systems will ramp up flow rate again once reheat turned on to avoid excessive reheat energy  Reheat is sometimes replace with a baseboard unit 32

Induction Unit  Flow from room or ceiling induced (Bernoulli

effect) and mixed with primary air stream

 Primary air flow rate reduced while keeping

actual flow relatively constant (avoids stagnant air concerns)

 Requires higher static pressures to achieve

induction effectthis leads to higher fan energy (though overall it should be reduced since this is VAV) 33

Fan-Powered Terminal Unit  Also referred to as “fan-powered VAV box”  Basic idea is to reuse heat from space, lights, etc. to provide the

      

“reheating” (similar to induction except we are now actively moving air with a fan) Better circulation due to increased air movement (over throttling unit) Parallel arrangement—local fan is outside primary air supply stream Series arrangement—local fan is inside primary air stream and runs when space is occupied Various heater options available to provide perimeter heating (coil, baseboard, radiant system) During unoccupied hours, main system can be shut off and local fans can be run to meet loads as needed Increase in fan energy over throttling units possibly offset by reuse of heat from space Noise a potential problem since fan is so close to occupied space

34

In-Room Terminal Systems: Main Characteristics Combined air and water system

components: 

Central air-conditioning equipment



Duct and water distribution systems



Room terminal units

35

In-Room Terminal Systems: Main Characteristics  “Primary” or ventilation air provided either centrally or locally 



  

Central air: handles indoor air quality requirements and latent loads (humidity) Centralized maintenance and lack of moisture condensation in the terminal units Requires ductwork but typically smaller than all-air systems Air can be supplied through the terminal unit or separately from it Moisture addition/removal can be accomplished centrally

 Local air: handles all conditioning requirements locally through

building apertures 





Eliminates requirements for ducts since outside air is introduced through terminal unit Increase in maintenance costs due to outside air handling “distribution” Generally lower first costs

36

In-Room Terminal Systems: Main Characteristics  Water supplied to local coils (“secondary water”) used to

provide additional conditioning beyond that which is done by the central air 





Usually sensible only—latent cooling at the terminal unit would significantly decrease the life of the unit and could lead to odors/bacterial growth Any condensate is typically left in space to get reabsorbed by room air at some later time (drain usually recommended) Can be either heating or cooling

 Applications 

 

Primarily exterior spaces with mainly sensible loads and no strict humidity control requirements Spaces where individual control is important or preferable Common installations: hospitals, hotels, schools, apartment buildings, office buildings, research laboratories

37

In-Room Terminal Systems: Main Characteristics Potential for heating without the

circulation of air (unoccupied periods, similar to baseboard heating) Main categories/arrangements    

Induction units Fan-coil units Two-, Three-, and Four-Pipe arrangements Packaged units 38

Induction Units: Characteristics  (Requires) centrally

supply fan outside air heat recovery

cooling coil

return air

relief air

Mixing Box

humidifier

primary air Zone

reheat/recool coil

induction unit

conditioned “primary” air supplied to unit  Uses Bernoulli effect to draws secondary air through secondary coil  Requires medium to high pressure to achieve secondary air flow  Secondary air flow is simply room air drawn into unit (through filter/screen and coil)  Units typically installed around perimeter of building near windows

induced air

39

Induction Units: Advantage  Individual temperature control on separate

thermostats at fairly low cost (biggest advantage)  Ducts and air handling units can be reduced in size since much of conditioning can be done locally  Moisture addition/removal, filtering, and outside air can be done centrally  Space heating during unoccupied hours does not require fan operation  Components last relatively long (15-25 years) with limited maintenance (cleaning filters and nozzles)

40

Induction Units: Disadvantages  Usually limited to perimeter spaces, requiring another system   

  

for interior spaces Primary air flow is constant and flow to units cannot be shutoff individually (local coils can be shutoff) Secondary air flow dependent on condition of lint screen and nozzle Potentially lower chilled water temperature needed due to reduce air flow to zones and desire to avoid local cooling coil condensation Not appropriate for spaces with high ventilation requirements since primary flow is reduced Local moisture sources (open windows, etc.) can cause unexpected condensation Higher initial costs and higher operating costs (due to high pressure requirements) than most air systems 41

Fan-Coil Units: Characteristics  Components: coils, fan/fan motor, filter, insulated condensate

pan/drain, controls/valves, return and supply air openings  Heating and cooling (though maybe only one at a time)  Forced convection from coil to air using local fan  Outside air locally or (usually) separate from the unit via a central source (example: high-rise hotels) 





Local outside air eliminates balancing problem if windows are opened Local outside air not allowed in commercial buildings because wind pressure changes outside reduce control over outside air Local outside air systems might require coil freeze protection

 Water (hot and/or cold) supplied from central source  Electric heater might be needed for a two-pipe system for

shoulder seasons

42

Fan-Coil Units: Types/Locations  Vertical units  Floor mounted, can also be low profile style  Usually installed at the perimeter under window sill  Low profile units can present maintenance problems  Horizontal units  Ceiling mounted, saving floor space  May use ductwork to distribute air (greater pressure required at fan)\  Can also combine air with central (outside) air  Maintenance and condensate handling more difficult though initial costs lower  Chase-enclosed units  Unit is typically floor to ceiling configuration  More likely to see these in hotels and residential buildings  Back-to-back placement with sound treatment

43

Fan-Coil Units: Selection and Capacity/Control Issues  Common technique is to select a unit that can meet

the cooling needs of a space at the medium speed setting of a three-speed unit (safety factor and less noise during most operation conditions)  Sizes can be reduced if outside air handled separately and introduced at a temperature close to room air conditions (~21°C)/reasonable humidity  Automated control on water flow rate, manual or auto control on air flow rate  On-off control not recommended (noise/circulation issues) 44

Fan-Coil Units: Water Distribution Schemes General considerations 

 



Pipes refer to fluid pipes entering and leaving the unit More pipes increases initial costs Less pipes requires “changeover” strategies and may result in lack of heating or cooling when needed All can be used with central ventilation 45

Fan-Coil Units: Water Distribution Schemes  Two-Pipe  One inlet pipe, one outlet pipe (single coil)  Heating and cooling happen seasonally with changeover from one to the other (problems during intermediate seasons)  Changeover typically determined by outdoor air temperature, all zones changeover at same time  Can result in frequent changeovers  Two-pipe changeover with partial or full electric strip heat can help avoid frequent changeovers by meeting smaller heating loads  Changeovers not necessary if building is dominated by either heating or cooling 46

Fan-Coil Units: Water Distribution Schemes  Three-Pipe  Two inlet pipes, common return pipe (two coils)  Generally not recommended since mixing the hot and cold water return is a waste of energy  Four-Pipe  Two inlet pipes, two outlet pipes (two coils)  Highest initial cost but best performance of fan coil units  May include a deadband between heating and cooling to avoid simultaneous heating/cooling 47

Fan-Coil Units: Advantages Individual control of spaces/central

water production Pipes require less space than ducts (easier for retrofits?) Potential lack of central AHU may also save space

48

Fan-Coil Units: Disadvantages Greater maintenance costs,

maintenance in occupied areas Multiple condensate drains problematic Ventilation may not be uniform or guaranteed if outside air is provided locally

49

Packaged Terminal Systems  Similar in concept to fan-coil units

except that cooling provided locally by “window AC” type unit  Heating can either be through central water/steam source or local (electric coil/heat pump)  Advantages/disadvantages similar to other air/water systems with additional concerns: 





Units have relatively short (appliance) life Concerns about outside air and water leaks into building through unit Noise from compressor can be excessive and variable 50

Summary  Induction Units:  Centrally conditioned “primary” air  Bernoulli effect to draws secondary air through secondary coil  Fan-Coil Units:  Forced convection from coil to air using local fan  Outside air locally or separate from the unit via a central source  Water (hot and/or cold) supplied from central source  Many other system types possible: packaged,

low temperature, evaporative, etc.

51

Lecture 15: Air Primary Loops and Controls


Purpose of this Lecture Gain an understanding of how to:  

Define primary air loops in EnergyPlus Control their operation and availability for conditioning thermal zones

2

Keywords Covered in this Lecture Air Primary Loop System Availability Manager List System Availability Manager:Scheduled System Availability Manager:Night Cycle Controller List Controller:Simple

3

Describing a Central Forced Air System Can be thought of as an “Air Loop” with

2 “sides”: 

Supply side: air primary loop and its associated objects  central fans, coils, etc.



Demand side: controlled zone equip configuration and its associated objects  air terminal units, fan coils, etc.

4

Describing a Central Forced Air System (cont’d) When we say “Air Loop” we will

normally mean the supply side of the overall air loop “Zone Equipment” will mean the demand side: all the stuff specific to a zone If no central air system, then there will be only zone equipment 5

Describing a Central Forced Air System (cont’d) Outside Air

Supply Side/Air Primary Loop

Supply Fan


Cooling Coil

CC

Relief Air

Resistive

Demand Side/Zone Equipment

Return Air Mixer

VAV Box:ReHeat

East

Zone Air Splitter

Zone

Zone VAV Box:ReHeat

North Zone VAV Box:ReHeat

6

Air Loop Simulation Simulates central air distribution, mixing,

and conditioning 



Equipment: supply & return fans, central heating and cooling coils, heat recovery, mixed air box Control: supply air temperature, outside air economizer

7

Air Loop Layout Zone Equipment Group

Main Supply Branch

Cold Branch

Zone Splitter Zones

Splitter Hot Branch

Zone Splitter

Zone Mixer

Zone Equip Group Outlet

Zone Equipm ent Group I nlets 8

Air Loop Layout (cont’d) Outside Air

Supply Fan


Heating/Cooling Coil

Relief Air Air Loop Inlet Node Zone Equip Outlet Node

Air Loop Outlet Node Zone Equip Inlet Node

9

Air Loop Syntax Map

10

Air Primary Loop  Controller List  System Availability Manager List  Branch List  Connector List  Connection to Zone Equipment  ReturnAir AirLoop Inlet Node  ZoneEquipGroup Outlet Node  SupplyAirPath ZoneEquipGroup Inlet Nodes  AirLoop Outlet Nodes 11

Air Primary Loop - Example AIR PRIMARY LOOP, Unitary System, !, !Avail List, !autosize, !Air Loop Branches, !, !Air Loop Inlet Node, !ZONE EQUIP OUTLET NODE, !Zone Equipment Inlet Node,!Air Loop Outlet Node; !-

Primary Air Loop Name Name: Controller List Name: System Availability Manager List Primary air design flow rate {m3/s} Air Loop Branch List Name Air Loop Connector List Name ReturnAir AirLoop Inlet Node ZoneEquipGroup Outlet Node SupplyAirPath ZoneEquipGroup In Nodes AirLoop Outlet Nodes

12

System Control High Level 

Similar to an energy management system



Set Point Managers  algorithms establish fluid loop set points



Availability Managers  make global on/off decisions

13

System Control (cont’d) Component Control 

Controllers  sense state at one point in system  control flow at another point to match set point



Integrated control  control integrated within component

14

System Control (cont’d) Plant: component sequencing & load

management Control is ideal 

PI/PID control is not modeled – would require shorter time steps

15

System Availability Managers Scheduled 

System availability determined by an on/off schedule

Night Cycle 

Used to cycle an air system on when one or more zones becomes too hot or too cold

16

System Availability Manager List Lists all of the applicable system

availability managers for a given air loop

SYSTEM AVAILABILITY MANAGER LIST, Furnace- Avail List, !- Name SYSTEM AVAILABILITY MANAGER:SCHEDULED, !- Type Furnace- Avail; !- System Availability Manager Name 1

17

System Availability Manager:Scheduled Simple on/off schedule SYSTEM AVAILABILITY MANAGER:SCHEDULED, Furnace- Avail, FanAndCoilAvailSched;

!- Name !- Schedule name

18

System Availability Manager:Night Cycle  Applicability schedule name  Fan schedule name  Control type 

Stay Off, Cycle On Any, Cycle On Control Zone, Cycle On Any - Zone Fans Only

 Thermostat on/off tolerance  Cycling run time  Control zone name 19

System Availability Manager:Night Cycle-Example SYSTEM AVAILABILITY MANAGER:NIGHT CYCLE, VAV Sys 1 Avail, !- Name SysAvailApplicSch, !- Applicability schedule name FanAvailSched, !- Fan schedule name Cycle On Any, !- Control type 4.0, !- thermostat on/off tolerance {deltaC} 7200.; !- Cycling run time {s}

20

Set Point Managers  Scheduled 

Uses a schedule to determine one or more set points

 Outside Air 



Sets the supply air temperature according to the outside air temperature using a reset rule Reset schedule determined by the supply air set point temperature at the outside high and low temperature

21

Set Point Managers (cont’d) Single Zone Reheat 

Calculates a set point temperature for the supply air that will satisfy the load of a controlled zone

Single Zone Minimum Humidity 

Calculates the supply air humidity ratio needed to maintain the zone relative humidity at or above a given set point 22

Set Point Managers (cont’d) Mixed Air 

Used to establish a temperature set point at the mixed air node  Set point must take into account any

downstream system fan heat



Outside air controller operates the outside air damper to meet this set point for economizer

23

Controllers  Simple 



Controls variable at one node based on the condition at another node For a cooling coil, the control node might be the outlet air temperature while the actuated variable is the flow rate through the coil

 Outside Air 

Controls mixed air box to use outside air for free cooling whenever possible

24

Controller List CONTROLLER LIST, VAV Sys 1 Controllers,

!- Name

Controller:Simple,

!- Controller Type 1

Central Cooling Coil Controller 1,

!- Controller Name 1

Controller:Simple,


Central Heating Coil Controller 1;


Repeat for each controller

25

Controller:Simple  Control_Node  really the sensed node  Actuator_Node  Controller convergence tolerance  Max actuated flow  Min actuated flow  Action  Reverse for cooling  Normal for heating 26

Controller:Simple - Example CONTROLLER:SIMPLE, Central Heating Coil Controller 1, !- Name TEMP, !- Control variable Normal, !- Action FLOW, !- Actuator variable VAV Sys 1 Outlet Node, !- Control_Node Main Heating Coil 1 Water Inlet Node, !- Actuator_Node 0.002, !- Controller Convergence Tolerance: delta from setpoint autosize, !- Max Actuated Flow {m3/s} 0.0; !- Min Actuated Flow {m3/s}

Action is “Normal” for heating, “Reverse” for cooling. 27

Summary  Central forced air systems in EnergyPlus

consist of an “air loop” (supply side) and a “zone equipment loop” (demand side)

 Primary air loop description contains:

controller list, availability manager, branch list, and connection information

 Setpoint manager used by controllers to

calculate current setpoint for various HVAC components 28

Lecture 16: Zone Air Paths and Air Distribution Units



Define the Zone Equipment (Demand Side) of an Air Loop  Zone Air Supply and Return Paths  Air Distribution Units  Examples of Zone Equipment

2

Keywords Covered in this Lecture Fan:Simple:VariableVolume Zone Air Supply Path Zone Air Return Path Zone Splitter and Zone Mixer (review) Direct Air Air Distribution Unit Single Duct:VAV:Reheat 3

Air Loop Components: Simple Example FAN:SIMPLE:VariableVolume, Supply Fan 1, FanAvailSched, 0.7, 600.0, 1.56, 0.45, 0.9, 1.0, 0.35071223, 0.30850535, -0.54137364, 0.87198823, 0.000, Main Heating Coil 1 Outlet Node, VAV Sys 1 Outlet Node;

!!!!!!!!!!!!!!!-

Fan Name Available Schedule Fan Total Efficiency Delta Pressure {Pa} Max Flow Rate {m3/s} Min Flow Rate {m3/s} Motor Efficiency Motor In Airstream Fraction FanCoefficient 1 FanCoefficient 2 FanCoefficient 3 FanCoefficient 4 FanCoefficient 5 Fan_Inlet_Node Fan_Outlet_Node

4

Zone Equipment Syntax Map Zone Equipment Loop Input Structure/Map Zone Supply Air Path data Component List

Controlled Zone Equip Configuration data Equipment List Inlet Node List Outlet Node List

etc. data

Component: Zone Control: Thermostatic data Control Type Schedule Control Type List

Zone Equipment List Air Distribution Unit Baseboard Window Air Cond

Zone Splitter

Zone Inlet Node List

selects control type from list

name up to 5 node numbers

Zone Outlet Node List

Control Types :

name up to 5 node numbers

Single Heating Setpoint Single Cooling Setpoint Single Heating Cooling Setpoint Dual Setpoint with DeadBand

Zone Return Air Path data Component List

Air Distribution Unit Single Duct:Const Vol:Reheat Dual Duct: Const Vol Dual Duct: VAV etc. data

Components: Zone Mixer

5

Air Path Zone Supply Air Path Zone Return Air Path

6

Zone Supply Air Path  Zone splitter 



Splits the supply air from the main air handler to serve individual zones Dual duct systems require splitters for both the cold and hot air ducts

 Zone supply plenum 



Allows system air to flow through a zone before it reaches the zone(s) to be served One supply plenum per air handler supply duct 7

Zone Supply Air Path Example Zone Supply Air Path 1 Zone Supply Air Splitter 1 Zone Eq In Node

Exhaust Fan

ZONE1 ATU In Node

ZONE2 ATU In Node

ZONE 3 ATU In Node

Supply Fan ZONE1

ZONE2

ZONE3

8

Zone Supply Air Path Example (cont’d) ZONE SUPPLY AIR PATH, Zone Supply Air Path 1, Zone Eq In Node, Zone Splitter, Zone Supply Air Splitter 1; ZONE SPLITTER, Zone Supply Air Splitter 1, Zone Eq In Node, ZONE1 ATU In Node, ZONE2 ATU In Node, ZONE3 ATU In Node;

!- name of object !- supply path inlet node !- type and name of component

!- name !- inlet node !- outlet nodes

9

Zone Return Air Path  Zone Mixer  Mixes the return air streams returning to the main air handler from individual zones  Zone return plenum  Allows system air to flow through a zone before it reaches the main return duct  Allows system air to be mixed from multiple zones, can eliminate the need for a zone mixer  Can mix plenum and ducted returns  Plenums may be in series or parallel (series temperatures lag by a zone time step) 10

Zone Return Air Path Example

Exhaust Fan

Supply Fan ZONE1

ZONE2

ZONE1 Outlet Node Return Air Mixer Outlet

ZONE2 Outlet Node

ZONE3

ZONE 3 Outlet Node

Zone Return Air Mixer Zone Return Air Path

11

Zone Return Air Path – Example with Return Plenum Supply Fan Outside Air

CC

HC


Relief Air

Space1-1

Return Air Plenum Zone

Space2-1

Zone Air Splitter

VAV Box:ReHeat

VAV Box:ReHeat

12

Zone Return Air Path Example (cont’d) ZONE RETURN AIR PATH, TermReheatReturnPath, Return Air Mixer Outlet, Zone Mixer, Zone Return Air Mixer;

!!!!-

Return Air Path Name Return Air Path Outlet Node KEY--System Component Type 1 Component Name 1

ZONE MIXER, Zone Return Air Mixer, Return Air Mixer Outlet, Zone 1 Outlet Node, Zone 2 Outlet Node, Zone 3 Outlet Node;

!!!!!-

Mixer Name Outlet_Node Inlet_Node_1 Inlet_Node_2 Inlet_Node_3

13

Air Loop Zone Equipment Direct Air Air Distribution Units

14

Zone Equipment Schematic Zone Supply Air Splitter

Return Air Path

Dual Duct Constant Volume (CV)

Zone Exhaust Branch (Opt.)

Dual Duct VAV


Zone 1

Select One

Low Temp Radiant

Select One

High Temp Radiant/ Convective

None




Local Convective Units

Select One Select One

Low Temp Radiant Panels Low Temp Rad Alternatives

High Temp Radiators

Radiators

Hi Temp Rad/Conv Alternatives

Baseboards

Window AC

Fan Coil

Unit Heater/ Ventilator

Air- Air HP

Water- Air HP & Ground Source HP

Local Conv. Unit Alternatives

15

Direct Air  Used to model systems in which central

system air is supplied directly to a zone  

Furnace Heat pump

 Central supply air may be controlled to meet

setpoints in a “control zone”  “Slave zones” typically have no individual control  “Slave zones” may have baseboards or other equipment to allow individual control 16

Direct Air - Example

Supply Fan

ZONE1 DirectAir

ZONE2 DirectAir

ZONE1 Inlet Node

ZONE2 Inlet Node

ZONE1 Node

ZONE1

ZONE1 Out Node Control Zone with thermostat

DIRECT AIR, Zone1DirectAir, FanAndCoilAvailSched, Zone 1 Inlet Node, 0.47;

!!!!-

ZONE2 Node

ZONE2

ZONE2 Out Node Slave Zone

Direct Air Name Schedule name for on/off schedule Zone Supply Air Node Name Maximum air flow rate {m3/s}

17

Air Distribution Units Allows equipment within the zone inlet

duct-work to be attached to the supply air stream Includes equipment that controls or tempers the air going into a zone such as dampers, reheat coils, etc. Only one ADU allowed per zone on a given air loop 18

Air Distribution Units (cont’d)  Air Distribution Units 

Single Duct Constant Volume Reheat



Single Duct VAV Reheat



Dual Duct Constant Volume



Dual Duct VAV



Powered Induction Units (Series and Parallel)

19

Air Distribution Units (cont’d) Dual Duct Constant Volume (CV)

Zone 1


Select One

Dual Duct VAV


None



20

Air Distribution Unit Example AIR DISTRIBUTION UNIT, SPACE1-1 ATU, SPACE1-1 In Node, SINGLE DUCT:VAV:REHEAT, SPACE1-1 VAV Reheat;

! ! ! !

Name unit type name

of air distribution unit outlet node of component of component

21

Single Duct:VAV:Reheat Example SINGLE DUCT:VAV:REHEAT, SPACE1-1 VAV Reheat, ReheatCoilAvailSched, SPACE1-1 Zone Coil Air In Node, SPACE1-1 ATU In Node, 0.33, 0.3, ! min air flow

! object name ! availability schedule ! zone heating coil inlet node ! terminal unit inlet node ! max air flow rate m3/s as decimal fraction of max air flow

SPACE1-1 Zone Coil Water In Node, ! water flow control node COIL:Water:SimpleHeating, ! heating component type SPACE1-1 Zone Coil, ! heating component name 0.0003, ! max water flow rate m3/s 0.0, ! min water flow rate m3/s SPACE1-1 In Node, ! terminal unit outlet node 0.001, ! convergence tolerance REVERSE ACTION; ! Damper Heating Action

22

Summary  Zone Equipment loop is the “demand side” of

a forced air system  Main parts of the zone equipment loop include:   

Supply and Return paths Thermostats Air Distribution Unit

 Can also add local radiative or convective

systems that serve the zone apart from the air loop 23

Lecture 17: VAV and Terminal Reheat Systems



Define Air Loops and Zone Equipment input for various types of fan systems  VAV  Terminal Reheat

Review various keywords already

covered and show how they interact to form a complete system definition 2

VAV Systems in EnergyPlus

VAV with Reheat and Outside Air Example Supply Fan

Outside Air

 Air Loop contains the Mixed Air CC


Return Air

Relief Air

Resistive

VAV Box: ReHeat

East Zone

Zone Air Splitter

Zone

R eturn Air M ixer

System, Supply Fan and the Cooling Coil Chilled Water Supply  Outside air system will be discussed later in more detail  Zone Equipment Loop contains the Splitter, VAV Box Air Distribution Unit, the zones, and the Return Air Path with the Mixer.

Chilled Water Return

VAV Box: ReHeat

North Zone VAV Box: ReHeat

4

VAV with Reheat Air Loop Outside Air

Supply Fan CC Mixed Outside Air Box

Relief Air


Chilled Water Supply

Return Air

Air Primary Loop, Typical Terminal Reheat 1, Reheat System 1 Controllers, Reheat System 1 Avail List, 1.3, Air Loop Branches, , Air Loop Inlet Node, Return Air Mixer Outlet Node, Zone Equipment Inlet Node, Air Loop Outlet Node;

!!!!!!!!!!-

Primary Air Loop Name Name: Controller List Name: System Availability Manager List Primary air design volumetric flow rate {m3/s} Air Loop Branch List Name Air Loop Connector List Name ReturnAir AirLoop Inlet Node ZoneEquipGroup Outlet Node SupplyAirPath ZoneEquipGroup Inlet Nodes AirLoop Outlet Nodes 5

VAV with Reheat Controller and Branch Lists Outside Air


Relief Air

Return Air



CONTROLLER LIST, Reheat System 1 Controllers, !- Name Controller:Simple, !- Controller Type 1 Main Cooling Coil Controller; !- Controller Name 1 BRANCH LIST, Air Loop Branches, !- Branch List Name Air Loop Main Branch; !- Branch Name 1

6

VAV with Reheat Main Branch Outside Air


Relief Air



Return Air

BRANCH, Air Loop Main Branch, 1.3, OUTSIDE AIR SYSTEM, OA Sys 1, Air Loop Inlet Node, Mixed Air Node, PASSIVE, FAN:SIMPLE:VariableVolume, Var Vol Supply Fan 1, Mixed Air Node, Cooling Coil Air Inlet Node, ACTIVE, < cont’d on next slide>

!!!!!!!!!!!!-

Branch Name Maximum Branch Flow Rate {m3/s} Comp1 Type Comp1 Name Comp1 Inlet Node Name Comp1 Outlet Node Name Comp1 Branch Control Type Comp2 Type Comp2 Name Comp2 Inlet Node Name Comp2 Outlet Node Name Comp2 Branch Control Type 7

VAV with Reheat Main Branch (cont’d) Outside Air


Relief Air



Return Air

COIL:Water:DetailedFlatCooling, Detailed Cooling Coil, Cooling Coil Air Inlet Node, Air Loop Outlet Node, PASSIVE;

!!!!!-

Comp3 Type Comp3 Name Comp3 Inlet Node Name Comp3 Outlet Node Name Comp3 Branch Control Type

8

VAV with Reheat System Availability Manager Outside Air


Relief Air

Return Air



SYSTEM AVAILABILITY MANAGER LIST, Reheat System 1 Avail List,

!- Name

SYSTEM AVAILABILITY MANAGER:SCHEDULED, !- System Availability Manager type 1 Reheat System 1 Avail;

!- System Availability Manager name 1

SYSTEM AVAILABILITY MANAGER:SCHEDULED, Reheat System 1 Avail,

!- Name

FanAndCoilAvailSched;

!- Schedule name 9

VAV with Reheat Supply Fan FAN:SIMPLE:VariableVolume, Var Vol Supply Fan 1, !- Fan Name CoolingCoilAvailSched, !- Available Schedule 0.7, !- Fan Total Efficiency 600.0, !- Delta Pressure {Pa} 1.3, !- Max Flow Rate {m3/s} Outside Air 0.20, !- Min Flow Rate {m3/s} 0.9, !- Motor Efficiency 1.0, !- Motor In Airstream Fraction 0.35071223, !- FanCoefficient 1 Relief Air 0.30850535, !- FanCoefficient 2 -0.54137364, !- FanCoefficient 3 0.87198823, !- FanCoefficient 4 0.000, !- FanCoefficient 5 Air Loop Inlet Node, !- Fan_Inlet_Node Cooling Coil Air Inlet Node; !- Fan_Outlet_Node


Return Air



10

VAV with Reheat Cooling Coil Outside Air


Relief Air

Return Air

COIL:Water:SimpleCooling, Main Cooling Coil 1, CoolingCoilAvailSched, autosize, autosize, 0.9, Main Cooling Coil 1 Water Inlet Node, Main Cooling Coil 1 Water Outlet Node, Mixed Air Node 1, Main Cooling Coil 1 Outlet Node;



!- Coil Name !- Available Schedule !- UA of the Coil {W/K} !- Max Water Flow Rate of Coil {m3/s} !- Leaving Relative Humidity of Coil !- Coil_Water_Inlet_Node !- Coil_Water_Outlet_Node !- Coil_Air_Inlet_Node !- Coil_Air_Outlet_Node 11

VAV with Reheat Cooling Coil Controller Outside Air


Relief Air

Return Air

Controller:Simple, Main Cooling Coil Controller, TEMP, Reverse, FLOW, Air Loop Outlet Node, Cooling Coil Water Inlet Node, 0.001, 0.0011, 0.0;



!- Name !- Control variable !- Action !- Actuator variable !- Control_Node !- Actuator_Node !- Controller Convergence Tolerance: delta temp from setpoint {C} !- Max Actuated Flow {m3/s} !- Min Actuated Flow {m3/s} 12

VAV with Reheat Zone Supply Air Path Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone

Zone VAV Box: ReHeat


ZONE SUPPLY AIR PATH, TermReheatSupplyPath,

!- Supply Air Path Name

Zone Equipment Inlet Node,

!- Supply Air Path Inlet Node

Zone Splitter,

!- KEY--System Component Type

Zone Supply Air Splitter;

!- Component Name 13

VAV with Reheat Zone Splitter Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE SPLITTER, Zone Supply Air Splitter,

!- Splitter Name


!- Inlet_Node

Zone 1 Inlet Node,

!- Outlet_Node_1

Zone 2 Inlet Node,

!- Outlet_Node_2

Zone 3 Inlet Node;

!- Outlet_Node_3 14

VAV with Reheat Zone Return Air Path Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE RETURN AIR PATH, TermReheatReturnPath,

!- Return Air Path Name

Return Air Mixer Outlet,

!- Return Air Path Outlet Node

Zone Mixer,

!- KEY--System Component Type 1

Zone Return Air Mixer;

!- Component Name 1 15

VAV with Reheat Zone Mixer Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE MIXER, Zone Return Air Mixer,

!- Mixer Name


!- Outlet_Node

Zone 1 Outlet Node,

!- Inlet_Node_1

Zone 2 Outlet Node,

!- Inlet_Node_2

Zone 3 Outlet Node;

!- Inlet_Node_3 16

VAV with Reheat Zone Equip Configuration Resistive Zone VAV Box: Reheat

CONTROLLED ZONE EQUIP CONFIGURATION, RESISTIVE ZONE,

!- Zone Name

Zone1Equipment,

!- List Name: Zone Equipment

Zone1Inlets,

!- List Name: Zone Inlet Nodes

,

!- List Name: Zone Exhaust Nodes

Zone 1 Node,

!- Zone Air Node Name

Zone 1 Outlet Node;

!- Zone Return Air Node Name 17

VAV with Reheat Zone Equipment List Resistive Zone VAV Box: Reheat

ZONE EQUIPMENT LIST, Zone1Equipment,

!- Name

AIR DISTRIBUTION UNIT,

!- KEY--Zone Equipment Type 1

Zone1TermReheat,

!- Type Name 1

1,

!- Cooling Priority

1;

!- Heating Priority

18

VAV with Reheat Air Distribution Unit Resistive Zone VAV Box: Reheat

AIR DISTRIBUTION UNIT, Zone1TermReheat,

!- Air Distribution Unit Name

Zone 1 Reheat Air Outlet Node,

!- Air Dist Unit Outlet Node Name

SINGLE DUCT:VAV:REHEAT,


Zone 1 VAV System;

!- Component Name 1

NODE LIST, Zone1Inlets,

!- Node List Name

Zone 1 Reheat Air Outlet Node;

!- Node_ID_1 19

VAV with Reheat VAV Terminal Unit SINGLE DUCT:VAV:REHEAT, SPACE1-1 VAV Reheat, ReheatCoilAvailSched, SPACE1-1 Zone Coil Air In Node, SPACE1-1 ATU In Node, 0.33, 0.3, SPACE1-1 Zone Coil Water In Node, COIL:Water:SimpleHeating, SPACE1-1 Zone Coil, 0.0003, 0.0, SPACE1-1 In Node, 0.001, REVERSE ACTION;

!!!!!!!!!!!!!!-

Name of System Availability schedule for VAV System Damper Outlet Node Damper Inlet Node Maximum air flow rate {m3/s} Min air flow fraction Control node Reheat Component Object Name of Reheat Component Max Reheat Water Flow {m3/s} Min Reheat Water Flow {m3/s} Reheat Air Outlet Node Convergence Tolerance Damper Heating Action

20

VAV with Reheat Reheat Coil Resistive Zone VAV Box: Reheat

COIL:Water:SimpleHeating, SPACE1-1 Zone Coil, ReheatCoilAvailSched, 300., 0.0003, SPACE1-1 Zone Coil Water In Node, SPACE1-1 Zone Coil Water Out Node, SPACE1-1 Zone Coil Air In Node, SPACE1-1 In Node;

!!!!!!!!-

Coil Name Available Schedule UA of the Coil {W/K} Max Water Flow Rate of Coil {m3/s} Coil_Water_Inlet_Node Coil_Water_Outlet_Node Coil_Air_Inlet_Node Coil_Air_Outlet_Node 21

Terminal Reheat Systems in EnergyPlus

TermReheat Controller and Branch Lists Outside Air


Relief Air

CONTROLLER LIST, Reheat System 1 Controllers, !- Name Controller:Simple, !- Controller Type 1 Main Cooling Coil Controller; !- Controller Name 1 BRANCH LIST, Air Loop Branches, !- Branch List Name Air Loop Main Branch; !- Branch Name 1

23

TermReheat Main Branch Outside Air


Relief Air

BRANCH, Air Loop Main Branch, 1.3, FAN:SIMPLE:VariableVolume, Var Vol Supply Fan 1, Air Loop Inlet Node, Cooling Coil Air Inlet Node, ACTIVE, COIL:Water:DetailedFlatCooling, Detailed Cooling Coil, Cooling Coil Air Inlet Node, Air Loop Outlet Node, PASSIVE;

!!!!!!!!!!!!-

Branch Name Maximum Branch Flow Rate {m3/s} Comp1 Type Comp1 Name Comp1 Inlet Node Name Comp1 Outlet Node Name Comp1 Branch Control Type Comp2 Type Comp2 Name Comp2 Inlet Node Name Comp2 Outlet Node Name Comp2 Branch Control Type 24

TermReheat System Availability Manager Outside Air


Relief Air

SYSTEM AVAILABILITY MANAGER LIST, Reheat System 1 Avail List,

!- Name

SYSTEM AVAILABILITY MANAGER:SCHEDULED, !- System Availability Manager type 1 Reheat System 1 Avail;

!- System Availability Manager name 1

SYSTEM AVAILABILITY MANAGER:SCHEDULED, Reheat System 1 Avail,

!- Name

FanAndCoilAvailSched;

!- Schedule name 25

TermReheat Supply Fan Outside Air


Relief Air

FAN:SIMPLE:ConstVolume, Supply Fan 1, FanAndCoilAvailSched, 0.7, 600.0, 1.3, 0.9, 1.0, Air Loop Inlet Node, Cooling Coil Air Inlet Node;

!!!!!!!!!-

Fan Name Available Schedule Fan Total Efficiency Delta Pressure {Pa} Max Flow Rate {m3/s} Motor Efficiency Motor In Airstream Fraction Fan_Inlet_Node Fan_Outlet_Node 26

TermReheat Cooling Coil Outside Air


Relief Air

COIL:Water:SimpleCooling, Main Cooling Coil 1, CoolingCoilAvailSched, autosize, autosize, 0.9, Main Cooling Coil 1 Water Inlet Node, Main Cooling Coil 1 Water Outlet Node, Mixed Air Node 1, Main Cooling Coil 1 Outlet Node;

!- Coil Name !- Available Schedule !- UA of the Coil {W/K} !- Max Water Flow Rate of Coil {m3/s} !- Leaving Relative Humidity of Coil !- Coil_Water_Inlet_Node !- Coil_Water_Outlet_Node !- Coil_Air_Inlet_Node !- Coil_Air_Outlet_Node 27

TermReheat Cooling Coil Controller Outside Air


Relief Air

Controller:Simple, Main Cooling Coil Controller, TEMP, Reverse, FLOW, Air Loop Outlet Node, Cooling Coil Water Inlet Node, 0.001, 0.0011, 0.0;

!- Name !- Control variable !- Action !- Actuator variable !- Control_Node !- Actuator_Node !- Controller Convergence Tolerance: delta temp from setpoint {C} !- Max Actuated Flow {m3/s} !- Min Actuated Flow {m3/s} 28

TermReheat Zone Thermostat Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE CONTROL:THERMOSTATIC, Zone 1 Thermostat, RESISTIVE ZONE, Zone Control Type Sched, SINGLE HEATING SETPOINT, Heating Setpoint with SB, SINGLE COOLING SETPOINT, Cooling Setpoint with SB;

!!!!!!!-

Thermostat Name Zone Name Control Type SCHEDULE Name Control Type #1 Control Type Name #1 Control Type #2 Control Type Name #2 29

TermReheat Thermostat Setpoints Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



SINGLE HEATING SETPOINT, Heating Setpoint with SB, Heating Setpoints;

!- Name !- Setpoint Temperature SCHEDULE Name

SINGLE COOLING SETPOINT, Cooling Setpoint with SB, Cooling Setpoints;

!- Name !- Setpoint Temperature SCHEDULE Name 30

TermReheat Zone Supply Air Path Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE SUPPLY AIR PATH, TermReheatSupplyPath,

!- Supply Air Path Name


!- Supply Air Path Inlet Node

Zone Splitter,

!- KEY--System Component Type

Zone Supply Air Splitter;

!- Component Name 31

TermReheat Zone Return Air Path Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE RETURN AIR PATH, TermReheatReturnPath,

!- Return Air Path Name


!- Return Air Path Outlet Node

Zone Mixer,


Zone Return Air Mixer;

!- Component Name 1 32

TermReheat Zone Splitter Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE SPLITTER, Zone Supply Air Splitter,

!- Splitter Name


!- Inlet_Node

Zone 1 Inlet Node,

!- Outlet_Node_1

Zone 2 Inlet Node,

!- Outlet_Node_2

Zone 3 Inlet Node;

!- Outlet_Node_3 33

TermReheat Zone Mixer Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



ZONE MIXER, Zone Return Air Mixer,

!- Mixer Name


!- Outlet_Node

Zone 1 Outlet Node,

!- Inlet_Node_1

Zone 2 Outlet Node,

!- Inlet_Node_2

Zone 3 Outlet Node;

!- Inlet_Node_3 34

TermReheat Zone Equip Configuration Resistive Zone VAV Box: ReHeat

CONTROLLED ZONE EQUIP CONFIGURATION, RESISTIVE ZONE,

!- Zone Name

Zone1Equipment,

!- List Name: Zone Equipment

Zone1Inlets,

!- List Name: Zone Inlet Nodes

,

!- List Name: Zone Exhaust Nodes

Zone 1 Node,

!- Zone Air Node Name

Zone 1 Outlet Node;

!- Zone Return Air Node Name 35

TermReheat Zone Equipment List Resistive Zone VAV Box: ReHeat

ZONE EQUIPMENT LIST, Zone1Equipment,

!- Name

AIR DISTRIBUTION UNIT,

!- KEY--Zone Equipment Type 1

Zone1TermReheat,

!- Type Name 1

1,

!- Cooling Priority

1;

!- Heating Priority

36

TermReheat Air Distribution Unit Resistive Zone VAV Box: ReHeat

AIR DISTRIBUTION UNIT, Zone1TermReheat,

!- Air Distribution Unit Name

Zone 1 Reheat Air Outlet Node,

!- Air Dist Unit Outlet Node Name

SINGLE DUCT:VAV:REHEAT,


Zone 1 VAV System;

!- Component Name 1

NODE LIST, Zone1Inlets,

!- Node List Name

Zone 1 Reheat Air Outlet Node;

!- Node_ID_1 37

TermReheat VAV Terminal Unit SINGLE DUCT:VAV:REHEAT, SPACE1-1 VAV Reheat, ReheatCoilAvailSched, SPACE1-1 Zone Coil Air In Node, SPACE1-1 ATU In Node, 0.33, 0.3, SPACE1-1 Zone Coil Water In Node, COIL:Water:SimpleHeating, SPACE1-1 Zone Coil, 0.0003, 0.0, SPACE1-1 In Node, 0.001, REVERSE ACTION;

!!!!!!!!!!!!!!-

Name of System Availability schedule for VAV System Damper Outlet Node Damper Inlet Node Maximum air flow rate {m3/s} Min air flow fraction Control node Reheat Component Object Name of Reheat Component Max Reheat Water Flow {m3/s} Min Reheat Water Flow {m3/s} Reheat Air Outlet Node Convergence Tolerance Damper Heating Action

38

TermReheat Reheat Coil Resistive Zone VAV Box: ReHeat

COIL:Water:SimpleHeating, SPACE1-1 Zone Coil, ReheatCoilAvailSched, 300., 0.0003, SPACE1-1 Zone Coil Water In Node, SPACE1-1 Zone Coil Water Out Node, SPACE1-1 Zone Coil Air In Node, SPACE1-1 In Node;

!!!!!!!!-

Coil Name Available Schedule UA of the Coil {W/K} Max Water Flow Rate of Coil {m3/s} Coil_Water_Inlet_Node Coil_Water_Outlet_Node Coil_Air_Inlet_Node Coil_Air_Outlet_Node 39

Summary This lecture highlighted the EnergyPlus

input necessary to define most VAV and Terminal Reheat systems 

Air loop and zone equipment input



Thermostat input



Fan and coil component input



Controller input

40

Lecture 18: Template Systems and Autosizing


Purpose of this Lecture  Introduce Templates—a time saving feature  Putting an actual system together in EnergyPlus (by hand) can be difficult and time consuming  Templates provide shorthand way of describing systems  Introduce Autosizing  Some components require sizes that the user may not know immediately  Autosizing asks EnergyPlus to size these automatically 2

HVAC System Templates Template Purpose Current Templates Future Templates Template Concepts Using HVAC Templates HVAC Template Structure Typical HVAC Systems Template Example Inputs/Results 3

Template Purpose HVAC system templates provide a

shorthand way of describing selected standard HVAC system configurations

4

Current Templates  Zone Thermostat  Purchased Air  Four Pipe Fan Coil  VAV Single Duct w/ Reheat  Packaged Furnace w/ DX Air Conditioner

5

Current Templates (cont’d)  Purchased Hot and Chilled Water Supply

Loops  Single Boiler and Chiller Supply Loops

6

Future Templates  Constant Volume Dual Duct  Variable Volume Dual Duct  VAV w/ Power Induction Unit  Heat Pumps  Add automatic autosizing to all templates  Provide “IDF Segments” for template systems  Multiple Boiler and Chiller Supply Loops  Multiple Equipment Condenser Loop

7

Template Concepts  Beneficial for setting up the loops, branches,

and nodes

 Not as beneficial for fans, pumps, chillers,

coils, etc.,

 The only "automatic" fields are the object

name, node names, and maybe flow rates.

 For autosized templates the defaults are

already specified

8

Template Concepts (NonAutosized) User assigns a template variable for

each of the remaining fields in the object for Fans, Coils, Chillers, etc… 



Advantage: order-independent keywords to assign values to Disadvantage: mapping the variable names to object fields is messy, and then the user has to go find the object documentation to understand what the variables really mean 9

Using HVAC Templates To describe typical HVAC system

configurations, a combination of system macro commands is used along with the required macro variable definitions prior to each command

10

HVAC Template Structure Input File.imf ##include HVACTemplates.imf Regular EnergyPlus objects RUN PERIOD, 1, 1, 12, 31; ... HVAC Template commands: ##set1 ZoneName = "RESISTIVE ZONE" ##set1 AvailSched = "FanAndCoilAvailSched" ##set1 HeatSuppAirTemp = 50 ##set1 CoolSuppAirTemp = 13 ##set1 HeatSuppAirHR = 0.015 ##set1 CoolSuppAirHR = 0.010 PurchAirZone[] ...

EP-Launch or RunEplus.bat

EP-Macro.exe

EPMIDF File Regular EnergyPlus objects after macro processing (“Clean IDF file”)

EnergyPlus.exe

EnergyPlus output files EnergyPlus output files EnergyPlus output files

11

Typical HVAC Systems Purchased Air System 

ZoneThermostat[ ] (once for each zone)



PurchAirZone[ ] (once for each zone)

Packaged Furnace w/ DX Cooling 




DirectAirZone[ ] (once for each zone)



UnitaryAirLoop[ ] 12

Typical HVAC Systems (cont’d) Single-Duct VAV System w/ OA Option 




VAVZone[ ] (once for each zone)



VAVAirLoop[ ]



ChilledWaterDemand[ ]



HotWaterDemand[ ]

13

Typical HVAC Systems (cont’d) Single Chiller Supply Plant 

ChillerSupply1[ ]



Condenser1[ ]

Single Boiler Supply Plant 

BoilerSupply1[ ]

14

Template Example Inputs Thermostat ##include HVACTemplates.imf ! Master Zone ##set1 ZoneName ##set1 ZoneCtrlSched ##set1 SnglHeatSPSched ##set1 SnglCoolSPSched ##set1 SnglHtClSPSched ##set1 DualSPHeatSched ##set1 DualSPCoolSched ZoneThermostat[]

= = = = = = =

! Command to insert template master file

"RESISTIVE ZONE" ! Zone name "Zone-Control-Type-Sched" ! Cntrl Type Sched "Heating-Setpoints" ! Single Heat SP Sched "Cooling-Setpoints" ! Single Cool SP Sched "None" ! Single Heat/Cool SP Sch "None" ! Dual SP Heat SP Sched "None" ! Dual SP Cool SP Sched

! Trigger the zone thermostat macro

15

Template Example Results Thermostat ZONE CONTROL:THERMOSTATIC, RESISTIVE ZONE Thermostat, RESISTIVE ZONE, Zone-Control-Type-Sched, Single Heating Setpoint, RESISTIVE ZONE SingleHeatSPSched , Single Cooling SetPoint, RESISTIVE ZONE SingleCoolSPSched ; SINGLE HEATING SETPOINT, RESISTIVE ZONE SingleHeatSPSched, Heating-Setpoints; SINGLE COOLING SETPOINT, RESISTIVE ZONE SingleCoolSPSched, Cooling-Setpoints;

16

Template Example Inputs – Direct Air Zone ##set1 ZoneName ##set1 AvailSched ##set1 ZoneSuppAirFlow DirectAirZone[]

= "RESISTIVE ZONE" ! Zone name = "FanAndCoilAvailSched" ! System Avail Sched = 2.0 ! Supply air flow [m3/s]

! Trigger the direct air zone macro

17

Template Example Results – Direct Air Zone CONTROLLED ZONE EQUIP CONFIGURATION, RESISTIVE ZONE, ! zone name RESISTIVE ZONE Equipment, ! zone equipment list RESISTIVE ZONE Inlets, ! inlet node list , ! exhaust node list RESISTIVE ZONE ZoneNode, ! zone node RESISTIVE ZONE OutletNode; ! zone outlet node ZONE EQUIPMENT LIST, RESISTIVE ZONE Equipment, ! name DIRECT AIR, RESISTIVE ZONE Direct Air, 1, 1; NODE LIST, RESISTIVE ZONE Inlets, ! name RESISTIVE ZONE AirTermInletNode; ! zone inlet is the direct air DIRECT AIR, RESISTIVE ZONE Direct Air, !- Direct Air Name FanAndCoilAvailSched, !- Schedule name for on/off schedule RESISTIVE ZONE AirTermInletNode, !- Zone Supply Air Node Name 2.0; !- Maximum air flow rate {m3/s}

18

HVAC Sizing Options Component Sizing Zone Sizing System Sizing Plant Sizing

19

Component Sizing Components are typically autosized

based on specified summer and winter design days. Global sizing factor optional 

Sizing factor typically >1.0



Sizing factor can be any value >0



Default 1.0

SIZING PARAMETERS, 1.2; !- sizing factor 20

Zone Sizing  Calculates required supply air volume to

maintain zone setpoints  Computes maximum cooling load, heating load and air flow for systems sizing and sizing zone components  Only controlled zones are included in zone sizing calculations  OA flow per person based on total number of people for all PEOPLE statements in zone (schedule values are not applied) 21

Zone Sizing (cont’d) ZONE SIZING, ZONE ONE, 14., 50., 0.009, 0.004, flow/person, 0.00944, 0.0, 0.0, design day, 0, design day, 0;

!!!!!!!!!!!!!!!-

Name of a zone Zone cooling design supply air temperature {C} Zone heating design supply air temperature {C} Zone cooling design supply air humidity ratio {kg-H20/kg-air} Zone heating design supply air humidity ratio {kg-H2O/kg-air} Outside air method Outside air flow per person {m3/s} Outside air flow {m3/s} Zone sizing factor Cooling design air flow method Cooling design air flow rate {m3/s} Heating design air flow method Heating design air flow rate {m3/s}

22

System Sizing  Calculates design air flow rates and heating

and cooling capacities based on specified supply air conditions and zone sizing results

 Must use zone sizing objects to force hard

sizes (will not read component sizes)

 Only controlled zones are included in system

sizing calculations

23

System Sizing (cont’d) SYSTEM SIZING, Unitary System, sensible, 0.0, 1.0, 0.0, 13.0, 50.0, noncoincident, no, no, 0.008, 0.008, design day, 0, design day, 0;

!!!!!!!!!!!!!!!!!!-

name of an AIR PRIMARY LOOP object type of load to size on Design (min) outside air volume flow rate {m3/s} minimum system air flow ratio Preheat design set temperature {C} Central cooling design supply air temperature {C} Central heating design supply air temperature {C} Sizing Option Cooling 100% Outside Air Heating 100% Outside Air Central cooling design supply air hum. ratio {kg-H2O/kg-air} Central heating design supply air hum. ratio {kg-H2O/kg-air} cooling design air flow method cooling design air flow rate {m3/s} heating design air flow method heating design air flow rate {m3/s}

24

Auto-Sizing Generate sizing report files (.zsz, .ssz) Outside air options Supply-side equipment sizing Size and “go” runs with computed sizes Uses all design days and selects max size

25

Auto-Sizing Calculation A “Purchased Air” simulation is

performed for each zone using user specified Design Day weather 



Purchased Air: hot or cold air supplied directly to a zone at a fixed temperature and with infinitely variable air flow. The Purchased Air simulation yields zone design air flow rates. 26

Auto-Sizing Calculation (cont’d) The zone design air flow rates are

summed to give central air handler coincident or non-coincident design flow rates. User specified design supply temperatures and the design weather conditions are used to calculate zone and system design heating and cooling capacities. 27

Auto-Sizing Calculation (cont’d) Coil UAs and other component inputs

are obtained by iterating the component models to meet the design outlet conditions Coil water flow rates are summed to obtain plant loop hot and chilled water flow rates

28

Auto-Sizing Input Run Control At least 2 design days Special day schedules for sizing Zone Sizing, System Sizing and Plant

Sizing Indicate with “Autosize” the inputs to be auto-sized 29

Zone Sizing Name of Zone Design cooling supply air temperature Design heating supply air temperature Design cooling supply air humidity ratio Design heating supply air humidity ratio

30

Zone Sizing (cont’d) Outside air method Outside air flow per person Outside air flow Zone sizing factor

31

Zone Sizing (cont’d) Cooling design air flow method Cooling design air flow rate Heating design air flow method Heating design air flow rate

32

Zone Sizing - Example ZONE SIZING, SPACE1-1, 14., 50., 0.009, 0.004, FLOW/PERSON, 0.00944, 0.0, 0.0, design day, 0, design day, 0;

!!!!!!!!!!!!!-

Name of a zone Zone cooling design supply air temperature {C} Zone heating design supply air temperature {C} Zone cooling design supply air humidity ratio Zone heating design supply air humidity ratio outside air method outside air flow per person {m3/s} outside air flow {m3/s} zone sizing factor cooling design air flow method cooling design air flow rate {m3/s} heating design air flow method heating design air flow rate {m3/s}

33

System Sizing Name of an AIR PRIMARY LOOP Type of load to size on 

Sensible, latent or total

Design (min.) outside air volumetric

flow rate Minimum system air flow ratio

34

System Sizing (cont’d) Preheat design set temperature Central cooling/heating design supply

air temperature Sizing Option 

Coincident or non-coincident

35

Plant Sizing Design loop exit temperature Design loop delta T Name of a PLANT LOOP or CONDENSER

LOOP Loop type – heat, cool, condenser

36

Run Control - example RUN CONTROL, Yes, ! zone sizing Yes, ! system sizing Yes, ! plant sizing No, ! design day full simulation Yes; ! weather file full simulation

Note: design days used here just to size 37

Sizing Schedules Example - 1 SCHEDULE, Clg-SetP-Sch, Temperature, Clg-SetP-WSch, 1, 1, 12, 31;

!- Name !- ScheduleType !- Name of WEEKSCHEDULE 1 !- Start Month 1 !- Start Day 1 !- End Month 1 !- End Day 1

38

Sizing Schedules Example - 2 WEEKSCHEDULE, Clg-SetP-Wsch, Clg-SetP-DSch-We, Clg-SetP-DSch-Wd, : Clg-SetP-DSch-Wd, Clg-SetP-DSch-We, Clg-SetP-DSch-We, Clg-SetP-DSch-SumDes, Clg-SetP-DSch-HighLimit, Clg-SetP-DSch-Wd, Clg-SetP-DSch-Wd;

!- Name !- Sunday DAYSCHEDULE Name !- Monday DAYSCHEDULE Name !- Friday DAYSCHEDULE Name !- Saturday DAYSCHEDULE Name !- Holiday DAYSCHEDULE Name !- SummerDesignDay DAYSCHEDULE Name !- WinterDesignDay DAYSCHEDULE Name !- CustomDay1 DAYSCHEDULE Name !- CustomDay2 DAYSCHEDULE Name

39

Sizing Schedules Example - 3 DAYSCHEDULE, Clg-SetP-DSch-SumDes, Temperature, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9, 23.9,

23.9, 23.9, 23.9, 23.9;

No setback for autosizing - will cause

oversizing to meet setback recovery within one timestep

40

What Inputs can be Auto-sized? Indicated in IDD file FAN:SIMPLE:VariableVolume, ….. N3 , \field Max Flow Rate \units m3/s \Autosizeable ….. 41

Asking for Auto-sizing In the IDF file: FAN:SIMPLE:VariableVolume, Supply Fan 1, !Fan Name FanAvailSched, !Fan Schedule 0.7, !Fan Efficiency 600.0, !Delta Pressure [N/M2] Autosize, !Max Vol Flow Rate [m3/S] Autosize, !Min Vol Flow Rate [m3/S] 0.9, !motor efficiency 1.0, !motor in air stream fraction 0.35071223, !Fan Coeff 1 Coeff's for Inlet Vane Dampers 0.30850535, !Fan Coeff 2 -0.54137364, !Fan Coeff 3 0.87198823, !Fan Coeff 4 0.000, !Fan Coeff 5 Main Heating Coil 1 Outlet Node, !Outlet Node VAV Sys 1 Outlet Node; !Inlet Node

42

Summary  Templates are a time saving feature that:  Provides a shorthand way of describing systems  Assists in the process of putting together EnergyPlus input  Autosizing helps the user:  Determine the size of equipment needed based on the building description, thermal loads, etc.  Avoids the need to provide a size for some equipment which may not be of interest but is still needed as input for EnergyPlus 43

Lecture 19: HVAC Outside Air Systems and Modeling Guidelines


Purpose of this Lecture Discuss Outside Air 



IAQ requirements force us to draw fresh air in from the outside environment Outside air (OA) can have a significant impact on the building energy requirements

Show how OA is specified in EnergyPlus

2

Keywords Covered in this Lecture Air Loop Equipment List Outside Air System Outside Air Mixer Controller:Outside Air Outside Air Inlet Node List Review of other related keywords

3

Components: Special Case Outside Air System OUTSIDE AIR SYSTEM is a subsystem component OA System Controller List OA System Equipment List OA System Availability Manager List

4

OA System Equipment List System component type 

outside air mixer, coil, heat exchanger

System component name Repeat for each air loop component

5

Air Loop Equipment List Example AIR LOOP EQUIPMENT LIST, OA Sys 1 Equipment, !- Name OUTSIDE AIR MIXER, !- KEY--System Component 1 OA Mixing Box 1; !- Component Name 1

6

Outside Air System - Example OUTSIDE AIR SYSTEM, OA Sys 1, OA Sys 1 Controllers, OA Sys 1 Equipment, VAV Sys 1 Avail List;

!!!!-

Name Name: Controller List Name of an Air Loop Equipment List Name of a System Availability Manager List

7

Outside Air Mixer Mixed_Air_Node Outside_Air_Stream_Node Relief_Air_Stream_Node Return_Air_Stream_Node

8

Outside Air Mixer - Example OUTSIDE AIR MIXER, OA Mixing Box 1, Mixed Air Node 1, Outside Air Inlet Node 1, Relief Air Outlet Node 1, VAV Sys 1 Inlet Node;

!!!!!-

Name Mixed_Air_Node Outside_Air_Stream_Node Relief_Air_Stream_Node Return_Air_Stream_Node

9

Outside Air Mixer – Controller List CONTROLLER LIST, OA Sys 1 Controllers, CONTROLLER:OUTSIDE AIR, OA Controller 1;

!- Name !- Controller Type 1 !- Controller Name 1

10

Controller:Outside Air Control_Node Actuated_Node Minimum outside air flow rate Maximum outside air flow rate Temperature limit Temperature lower limit

11

Controller:Outside Air Example CONTROLLER:OUTSIDE AIR, OA Controller 1, ECONOMIZER, NO RETURN AIR TEMP LIMIT, NO RETURN AIR ENTHALPY LIMIT, NO LOCKOUT, FIXED MINIMUM, Mixed Air Node 1, Outside Air Inlet Node 1, autosize, autosize, 19., 4., 0.0, Relief Air Outlet Node 1, VAV Sys 1 Inlet Node, Min OA Sched;

!!!!!!!!!!!!!!!!-

Name EconomizerChoice ReturnAirTempLimit ReturnAirEnthalpyLimit Lockout MinimumLimit Control_Node Actuated_Node min outside air flow rate {m3/s} max outside air flow rate {m3/s} temperature limit {C} temperature lower limit {C} enthalpy limit {J/kg} Relief_Air_Outlet_Node Return_Air_Node Minimum Outside Air Schedule Name

12

TermReheat with Outside Air Example Supply Fan

Outside Air

 Air Loop contains the Mixed Air CC


System

Relief Air

Resistive

Return Air Mixer

VAV Box: ReHeat

East

Zone Air Splitter

Zone



13

TermReheat Main Branch with OA System Outside Air


Relief Air

BRANCH, Air Loop Main Branch, 1.3, OUTSIDE AIR SYSTEM, OA Sys 1, VAV Sys 1 Inlet Node, Mixed Air Node, PASSIVE, FAN:SIMPLE:ConstVolume, Supply Fan 1, Mixed Air Node, < cooling coil >

!!!!!!!!!!-

Branch Name Maximum Branch Flow Rate {m3/s} Comp1 Type Comp1 Name Comp1 Inlet Node Name Comp1 Outlet Node Name Comp1 Branch Control Type Comp2 Type Comp2 Name Comp2 Inlet Node Name

14

TermReheat Outside Air Node List Outside Air


Relief Air

OUTSIDE AIR INLET NODE LIST, OutsideAirInletNodes;

!- 1st Node name or node list name

NODE LIST, OutsideAirInletNodes,

!- Node List Name

Outside Air Inlet Node 1;

!- Node_ID_1

15

TermReheat Outside Air System Outside Air


Relief Air

OUTSIDE AIR SYSTEM, OA Sys 1,

!- Name

OA Sys 1 Controllers,

!- Name: Controller List

OA Sys 1 Equipment,

!- Name of an Air Loop Equipment List

VAV Sys 1 Avail List;

!- Name of a System Availability Manager List

16

TermReheat Outside Air Controller List Outside Air


Relief Air

CONTROLLER LIST, OA Sys 1 Controllers,

!- Name

CONTROLLER:OUTSIDE AIR,


OA Controller 1;


17

TermReheat Outside Air Equipment List Outside Air


Relief Air

AIR LOOP EQUIPMENT LIST, OA Sys 1 Equipment,

!- Name

OUTSIDE AIR MIXER,

!- KEY--System Component 1

OA Mixing Box 1;

!- Component Name 1

18

TermReheat Outside Air Controller CONTROLLER:OUTSIDE AIR, OA Controller 1, ECONOMIZER, NO RETURN AIR TEMP LIMIT, NO RETURN AIR ENTHALPY LIMIT, NO LOCKOUT, FIXED MINIMUM, Mixed Air Node 1, Outside Air Inlet Node 1, 0.468, 1.56, 19., 4., 0.0, Relief Air Outlet Node 1, VAV Sys 1 Inlet Node, Min OA Sched;

!- Name !- EconomizerChoice !- ReturnAirTempLimit !- ReturnAirEnthalpyLimit !- Lockout !- MinimumLimit !- Control_Node !- Actuated_Node !- minimum outside air flow rate {m3/s} !- maximum outside air flow rate {m3/s} !- temperature limit {C} !- temperature lower limit {C} !- enthalpy limit {J/kg} !- Relief_Air_Outlet_Node !- Return_Air_Node !- Minimum Outside Air Schedule Name 19

TermReheat Outside Air Mixer Outside Air


Relief Air

OUTSIDE AIR MIXER, OA Mixing Box 1,

!- Name

Mixed Air Node 1,

!- Mixed_Air_Node

Outside Air Inlet Node 1,

!- Outside_Air_Stream_Node

Relief Air Outlet Node 1,

!- Relief_Air_Stream_Node

VAV Sys 1 Inlet Node;

!- Return_Air_Stream_Node 20

Outdoor Air Economizer TermReheatOA.idf example file CONTROLLER:OUTSIDE AIR, OA Controller 1, !- Name ECONOMIZER, !- EconomizerChoice NO RETURN AIR TEMP LIMIT, !- ReturnAirTempLimit NO RETURN AIR ENTHALPY LIMIT, !- ReturnAirEnthalpyLimit NO LOCKOUT, !- Lockout FIXED MINIMUM, !- MinimumLimit Mixed Air Node, !- Control_Node Outside Air Inlet Node, !- Actuated_Node 0.4333, !- minimum outside air flow rate {m3/s} 1.3, !- maximum outside air flow rate {m3/s} 19., !- temperature limit {C} 4., !- temperature lower limit {C} 0.0, !- enthalpy limit {J/kg} Relief Air Outlet Node, !- Relief_Air_Outlet_Node VAV Sys 1 Inlet Node; !- Return_Air_Node

21

Outdoor Air Economizer (cont’d) Scheduled mixed air setpoint SET POINT MANAGER:SCHEDULED, Mixed Air Temp Manager, !- Name TEMP, !- Control variable Seasonal Reset Mixed Air Temp Sch, !- Schedule Name Mixed Air Nodes; !- Name of the set point Node List NODE LIST, Mixed Air Nodes, !- Node List Name Mixed Air Node; !- Node_ID_1

22

Outdoor Air Economizer (cont’d) Mixed air setpoint adjusted for fan heat SET POINT MANAGER:SCHEDULED, Supply Air Temp Manager 1, !- Name TEMP, !- Control variable Seasonal Reset Supply Air Temp Sch, !- Schedule Name Supply Air Temp Nodes 1; !- Name of the set point Node List SET POINT MANAGER:MIXED AIR, Mixed Air Temp Manager 1, !- Name TEMP, !- Control variable: VAV Sys 1 Outlet Node, !- reference set point node name Main Heating Coil 1 Outlet Node, !- fan inlet node name VAV Sys 1 Outlet Node, !- fan outlet node name Mixed Air Node 1; !- Name of the set point Node or Node List NODE LIST, Supply Air Temp Nodes 1, !- Node List Name VAV Sys 1 Outlet Node; !- Node_ID_1 23

Economizer with Furnace/DX Furnace/DX does not set a supply air

setpoint Must use setpoint managers to establish a setpoint

24

Summary Introduction of outside air into a forced

air system is necessary to meet indoor air quality (IAQ) standards Outside air (mixing box) in EnergyPlus is a component on an air loop branch Outside air system also contains controllers that can be operated in economizer mode

25

Lecture 20: Radiant Systems


Importance of this Lecture to the Simulation of Buildings  Forced air systems tend to dominate the US

market  

Systems are relatively easy to understand Control on air temperature pretty straightforward

 Air systems do not guarantee comfort which

is a function of other variables besides air temperature  Other systems, such as radiant systems, may be a better option for some cases  Ability to simulate different system types is critical to the fair and accurate comparison of energy consumption 2




Radiant systems overview: characteristics, types, advantages, and potential problems How to specify different types of radiant systems in EnergyPlus

3

Keywords Covered in this Lecture Low Temp Radiant System:Hydronic Construction With Internal Source Surface:HeatTransfer (review) Radiant System Surface Group Low Temp Radiant System:Electric High Temp Radiant System

4

Radiant Systems Overview

Low Temperature Radiant Systems High Temperature Radiant Systems Hybrid Systems

Radiant System Overview  Conventional Forced Air Systems: aim to affect the

thermal comfort of space occupants by conditioning air and delivering it to a space  

Primary effect is on space air temperature Controls are simple but do not always guarantee comfort

 Radiant Systems: aim to affect the thermal comfort

of space occupants by modifying the radiant field within a space   

Primary effect can be on surface temperatures Some systems are simply direct radiant sources Controls are more complex but inclusion of radiant effects may result in better comfort at lower air temperatures 6

Radiant System Overview (cont’d)  Definition: system which supplies a majority of its

energy to a space via radiation  Main System Types (Temperature Classifications)  

Low Temperature Radiant Systems High (and Medium) Temperature Radiant Systems (heating only)

 Indoor Air Quality (IAQ) Issues  IAQ linked to introduction of outside air, but radiant systems lack an air stream  Dust, dirt, etc. not spread around by forcing air circulation  IAQ concerns may require the use of a “hybrid” system

7

Radiant System Overview (cont’d)  Overall Advantages    

Less extreme water conditions Lack of architectural effect Potential energy savings Warm floor effect

 Market Issues 



While gaining in popularity in US, market percentage is still fairly small (lack of knowledge/understanding about systems, IAQ concerns) Much more popular in Asia and Europe where it is used in much more diverse settings (not just residences)

 Safety/Comfort Issues 



Concerns about high temperature surfaces within space (burns, fires) Limits on wall, floor temperatures (maximum 8

Low Temperature Radiant Systems  System components  Thermostat (air, radiant, or “operative”)  Radiant surface (embedded in a particular building element)  Resistance wires or water tubing  Control valves and headers  Primary system (boiler/chiller)  System classifications  Hydronic (water, air also possible) or electric  Heat source/sink embedded in a surface: floor, wall, ceiling, or panel  High mass or low mass  Heating or cooling (hydronic only) though only one at a time (like a two-pipe air system) 9

Low Temperature Radiant Systems (cont’d)  Energy efficiency issues  Conditioning surfaces not air—may allow more extreme air temperatures while maintaining the same amount of comfort  No fan energy  More “extreme” air temperatures should result in less infiltration heat gain/loss  Heat gain/loss through surfaces—more or less?  Back and edge losses—may require more insulation  Choice of floor covering might decrease system efficiency  Condensation potential (indoor rain)—cooling systems may require an air loop to avoid moisture condensing on the system

10

Low Temperature Radiant Systems (cont’d)  Alternative energy sources  Standard source for heating/cooling system is a boiler or chiller  Potential for using alternative energy sources may be higher than with conventional systems due to less extreme water conditions  Use of mass to shift energy needs  Link to solar hot water heaters (interior or exterior)  Link to ground loop  Link to cooling tower/evaporative cooler (cooling only)  Nighttime ventilation (ventilated slab)  Link to a nearby water source (pond, lake, stream, etc.) 11

Low Temperature Radiant Systems (cont’d)  Applications  







Many—typically used most often in residential Buildings where warm floors are beneficial (e.g., garages) Buildings where air systems might contaminate (other) areas (hospitals, clean rooms, etc.) Buildings where IAQ obtained with minimal air systems Snow/ice melting 12

High Temperature Radiant Systems  General characteristics  Also known as “Infrared Radiant Heating”  High temperature due to characteristic temperatures of radiant heaters (range from 150 to 2760°C)

 Low- and medium-intensity (up to ~1000°C) typically gas-fired  High-intensity (above 1000°C) use electric resistance heating



Highly directional in nature—generally good for spot heating  Can result in spaces with highly variable levels of thermal comfort  Direction depends on type, reflector, and shape

 

Shapes: tube or lamp Heating only—cooling would be provided by some other means 13

High Temperature Radiant Systems (cont’d) System components 

Burner or wire/filament



Housing (shape depends on type)



Reflector (redirects radiation toward space



Power connection or gas inlet/combustion exhaust

14

High Temperature Radiant Systems (cont’d)  Energy efficiency issues  Similar benefits as low temperature radiant heaters: lower air temperatures and no fan energy  Not all radiation is infrared—some might actually go “out the window”  Safety issues of the high temperature surface within a space  Applications  Large spaces: hangars, factories, warehouses, gymnasiums  Open areas: loading docks, outdoor areas (stadiums or restaurants), pools, building entrances  Snow/ice melting

15

Hybrid Systems: Cool Beam  Shaped and positioned like a high

temperature radiant heater but supplied with chilled water (from plant or alternate source)

 Condensate pan to avoid temporary dripping

into space

 Air movement via buoyancy effects or small

fan

 Some radiant effect

16

Hybrid Systems: Combined Forced Air/Radiant System  Sometimes referred to as a “hybrid” system  Usually due to condensation or perhaps for IAQ concerns  Radiant system is run as the primary system for heating and

cooling  In cooling mode, forced air loop turns on when condensation likely (based on moisture levels in the air)  Chilled water sent to forced air coil first and then to radiant system (to help avoid condensation in the space)  Benefits of radiant system but initial costs of two systems

17

Hybrid Systems: UFAD  Sort of a “pseudo-radiant” system

Underfloor air distribution (floor supply

plenum) can turn the floor into a radiant system—in effect a hybrid system Exact effect on comfort not yet studied since technology is still fairly new 18

Radiant Systems in EnergyPlus

Radiant System Overview  Low Temperature Radiant Systems  Two types:

 Hydronic (must be hooked up to a fluid loop—plant or

condenser)  Electric 

System serves as:

 Heat transfer surface with an embedded source or sink

(heating or cooling)  Space conditioning system 

Important keywords:     

Construction With Internal Source Surface:HeatTransfer Low Temp Radiant System:Hydronic Low Temp Radiant System:Electric Radiant System Surface Group

20

Radiant System Overview (cont’d) High Temperature Radiant Systems  Two types:  Electric  Gas 



System is only seen as a space conditioning (heating) system Important keywords:  High Temp Radiant System  Radiant System Surface Group 21

Radiant System Controls  Thermostatic control  Zone Thermostat determines whether system is in heating, cooling, or “float” mode  If zone thermostat says the system is on, the radiant temperature schedule determines the response of the system  System fluid flow varies linearly around the setpoint temperature (user also specifies a throttling range  Fluid loop temperature controlled by plant/condenser loop

Mass Flow Rate

Setpoint Temperature

Heating

Controlling Temperature Throttling Range

Mass Flow Rate

Setpoint Temperature Cooling

Controlling Temperature Throttling Range

22

Radiant System Controls (cont’d)  Control temperature 

In determining the system response, the radiant control setpoint can be compared to a variety of other temperatures depending on the type of control one desires:  Zone Mean Air Temperature  Zone Mean Radiant Temperature  Zone Operative Temperature (average of MAT and MRT)  Outside Air Dry-Bulb Temperature (low temperature

systems only)  Outside Air Wet-Bulb Temperature (low temperature systems only) 23

Radiant System Controls (cont’d)  Single Surface or Serial Control  Radiant system description for each individual surface  Control is staged via priority in zone equipment list  Top priority surface will attempt to meet entire load; when it cannot, next highest priority surface will attempt to meet load, etc.  Multiple Surface or Parallel/Coordinated Control  One radiant system description for a group of surfaces  Control of all surfaces in this group are identical  Split of fluid flow determined by Radiant System Surface Group input RADIANT SYSTEM SURFACE GROUP, Zone 1 Rad Surfs, Zn001:Flr001, 0.75, Zn001:Roof001, 0.25;

!!!!!-

name of surface list Surface name 1 Flow fraction for surface 1 Surface name 2 Flow fraction for surface 224

Low Temperature Surface Input IDF Example: CONSTRUCTION WITH INTERNAL SOURCE, Slab Floor with Radiant, !- Name 3, !- Source present after this layer in definition below 4, !- Temperature calculation requested after this layer 1, !- Dimensions for the CTF calculation (1- or 2-D) 0.1524, !- Tube Spacing {m} CONCRETE - DRIED SAND AND GRAVEL 4 IN, !- Outside Layer INS - EXPANDED EXT POLYSTYRENE R12 2 IN, !- Layer #2 GYP1, !- Layer #3 GYP2, !- Layer #4 FINISH FLOORING - TILE 1 / 16 IN; !- Layer #5

Based on the above input, the tubing (and thus the heat source or sink) would be applied between layers 3 and 4 in this construction 25

Low Temperature Surface Input (cont’d) IDF Example: Surface:HeatTransfer, Zn002:Flr001, !- User Supplied Surface Name Floor, !- Surface Type Slab Floor with Radiant, !- Construction Name of the Surface EAST ZONE, !- Inside Face Environment Ground, !- Outside Face Environment , !- Outside Face Environment Object NoSun, !- Sun Exposure NoWind, !- Wind Exposure 1.000000, !- View Factor to Ground 4, !- Number of Surface Vertice Groups -- Number of (X,Y,Z) group 6.096,0.0,0.0, !- X,Y,Z ==> Vertex 1 6.096,6.096,0.0, !- X,Y,Z ==> Vertex 2 12.192,6.096,0.0, !- X,Y,Z ==> Vertex 3 12.192,0.0,0.0; !- X,Y,Z ==> Vertex 4 26

Hydronic Radiant Input IDF Example:

Could be name of a Radiant System Surface Group

LOW TEMP RADIANT SYSTEM:HYDRONIC, East Zone Radiant Floor, !- name of hydronic low temperature radiant system RadiantSysAvailSched, !- availability schedule East Zone, !- Zone name (name of zone system is serving) Zn002:Flr001, !- Surface name (name of surface tubes embedded in) or list name 0.012, !- Hydronic tubing inside diameter {m} 400.0, !- Hydronic tubing length (total length of pipe embedded) {m} MAT, !- temperature control type (MAT|MRT|OPERATIVE|ODB|OWB) 0.00008, !- maximum hot water flow {m3/s} East Zone Radiant Water Inlet Node, !- heating water inlet node East Zone Radiant Water Outlet Node, !- heating water outlet node 2.0, !- heating control throttling range {C} Radiant Heating Setpoints, !- heating control temperature schedule 0.0012, !- maximum cold water flow {m3/s} Zone 2 Cooling Water Inlet Node, !- cooling water inlet node Zone 2 Cooling Water Outlet Node, !- cooling water outlet node 2.0, !- cooling control throttling range {C} Radiant Cooling Setpoints; !- cooling control temperature schedule

Separate input for heating and cooling

27

Electric Low Temperature Radiant Heating Systems IDF Example: LOW TEMP RADIANT SYSTEM:ELECTRIC, Zone 1 Elec Floor, !- name of electric low temperature radiant system RadPanelAvailSched, !- availability schedule NORTH ZONE, !- Zone name (name of zone system is serving) Zone 1 Rad Surfs, !- Surface name or Radiant System Surface Group name 10000, !- maximum electrical power to panel {W} MRT, !- temperature control type (MAT|MRT|Operative|ODB|OWB) 2.0, !- heating throttling range {C} Radiant Heating Setpoints; !- heating setpoint temperature schedule

Note: Input similar to hydronic radiant system except no fluid loop information and no cooling information

28

High Temperature Radiant Systems Affects thermal comfort directly, then convected to zone air

IDF Example:

Energy has no effect on zone or any surface

HIGH TEMP RADIANT SYSTEM, Zone 1 Radiant Heater, !- name of high temperature radiant system RadiantPanelAvailSched, !- availability schedule NORTH ZONE, !- Zone name (name of zone system is serving) 10000, !- maximum power input {W} GAS, !- type of high temperature radiant heater (GAS|ELECTRIC) 0.85, !- combustion efficiency (ignore for electric radiant heaters) 0.75, !- fraction of input converted to radiant energy 0.00, !- fraction of input converted to latent energy 0.00, !- fraction of input that is lost (vented to outside environment) OPERATIVE, !- temperature control type (MAT|MRT|OPERATIVE) 2.0, !- heating throttling range {C} Radiant Heating Setpoints, !- heating setpoint temperature schedule 0.05, !- fraction of radiant energy incident on people Zn001:Flr001, !- surface to which radiant energy from heater is distributed 0.75, !- fraction of radiant energy from heater distributed to surface Zn001:Wall001, !- surface to which radiant energy from heater is distributed 0.25; !- fraction of radiant energy from heater distributed to surface User-defined output pattern, fraction must add to 1

29

Summary  Radiant systems use radiation as the primary

mode of heat transfer to heat space occupants directly rather than indirectly by conditioning air

 Low and high temperature radiant systems

can be defined in EnergyPlus as zone equipment

 Hydronic radiant systems are connected to a

primary system loop much like a water coil

30

Lecture 21: Introduction to Primary Systems (Central Plants)


Importance of this Lecture to the Simulation of Buildings Primary systems provide hot and chilled

water for the secondary systems as well as other energy sources that are needed by the building Some knowledge of the primary systems (central plants) is required to accurately simulate buildings and to understand what the model input parameters are 2




Basic information about primary plants (central plants) Interconnection between primary plants and the rest of the building

3

Cooling Equipment

Chillers: Compression-Based and Absorption Heat Pumps Rooftop/DX Packaged Units Thermal Energy Storage (Water and Ice)

Compression-Based Liquid Chilling Systems  Compression Chillers and Heat Pumps both work on

what is commonly referred to as a “vapor compression cycle”  

Thermodynamic cycle through which refrigerant goes Refrigerant is enclosed within cycle components

 Components  Condenser  Compressor  Evaporator (aka Liquid Cooler)  Expansion Valve  Primary and secondary fluids (refrigerant, water, etc.)

5

Compression Cycle Typical compression cycle diagram: Condenser

High Pressure Low Pressure

QC Compressor

Work

Expansion Valve

Evaporator

QE 6

Compression-Based Liquid Chilling Systems (cont’d)  Cycle Details  High pressure side: from compressor outlet through condenser to expansion valve inlet  Low pressure side: from expansion valve outlet through evaporator to compressor inlet  Utilize the fact that the boiling point of the refrigerant changes as the fluid pressure changes: lower pressure means a lower boiling temperature  Refrigerant picks up heat in the evaporator (refrigerant evaporates) because the chilled fluid temperature is higher than the refrigerant temperature  Refrigerant rejects heat in the condenser (refrigerant condenses) because condenser fluid temperature is lower than refrigerant temperature  Compressor drives the cycle by compressing the refrigerant through the addition of work  First Law of Thermodynamics

7

Chillers/Heat Pumps for Conditioning  Cooling: Normal operation mode  Goal is to provide cooling at the evaporator where there is chilled water or air that is produced  Coefficient of performance (COP) equal to cooling achieved at the evaporator over the work required at the compressor  Heating: Reverse operation (heat pumps)  Goal is to provide heating at the condenser where there is hot water or air that is produced  Typically this requires a reversal of refrigerant flow  Coefficient of performance (COP) equal to heating achieved at the condenser over the work required at the compressor 8

Chillers/Heat Pumps for Conditioning (cont’d)  Efficiency and Energy Issues  Work is required because we are trying to get heat to flow in a direction that is counter the natural flow of heat (natural would be from higher temperature to lower temperature)  COP is generally greater than 1.0 so we get more kW-h of cooling or heating than electric kW-h that we put into the compressor  Performance (and COP) of the system is highly dependent on the fluid temperatures that the condenser and evaporator are in contact with  Lower evaporator temperatures result in lower COP  Higher condenser temperatures result in lower COP  More extreme temperatures lower COP and can lower available

capacity



Temperature relation to performance can be a hindrance to the system or a potential advantage  Heat pump may struggle and require more energy as outside

temperatures become more extreme  Presence of a more moderate/constant temperature source can keep system running efficiently (e.g., ground)

9

Chillers/Heat Pumps for Conditioning (cont’d)  Chiller vs. Heat Pumps—what’s the

difference?  







Difference in system components: none Chillers are generally cooling only device and are used to produce chilled water for cooling coils (size range can be quite large) Heat pumps can provide both heating and cooling and are typically smaller in size (often residential units) Heat pumps are typically compression cycle only and almost all use electric energy as input Chillers can use various cycles and may actually use other energy sources as the system energy input

10

Condensers  Purpose: to reject heat from refrigerant to

surrounding environment, condensing the refrigerant from a (superheated) vapor to a (subcooled) liquid  Condenser is really a “heat exchanger” which transfers energy from one fluid stream to another without mixing the two streams  Water-Cooled Condensers 



Heat exchanged with water which is circulated to another “component” (ground, lake, pond—natural or constructed, river, cooling tower, etc.) as closed or open loop Condenser temperature depends on water source temperature 11

Condensers (cont’d)  Air-Cooled Condensers  Heat exchanged with outdoor air  Fans required to improve heat transfer  Condenser temperature linked to outside air dry bulb temperature  Evaporative Condensers  Heat exchanged sensibly and latently with outdoor air  Fan and pump required: fan to circulate air through unit, pump to circulate water  Added evaporation process increases performance  Condenser temperature linked to outside wet bulb temperature (less than or equal to dry bulb)  Condenser water and evaporative water kept separat 12

Condensers (cont’d) Cooling Towers 

Similar concept as evaporative condensers



Condenser water “open” in the tower





Some water evaporates, requiring make-up water Some systems eliminate the fan requirement

13

Condenser Examples

14

Condenser Examples (cont.)

15

Digital images on this slide courtesy of: Lisa Fricker, Graduate Student, UIUC

16

Condenser Examples (cont.)

17

Evaporators (Liquid Coolers)  Purpose: to absorb heat in the refrigerant

from the surrounding environment, evaporating the refrigerant from a liquid (or liquid/vapor mixture) to a (superheated) vapor  Evaporator is also a heat exchanger  Evaporator can be a cooling coil itself or a refrigerant (DX or direct expansion coil) to water heat exchanger to the chilled water loop 18

Heat Exchangers  Heat Exchanger Types (largest to smallest):  Shell-and-Tube  Plate/Plate-and-Frame  Tube-in-Tube  Shell-and-Coil  Heat Exchanger Issues:  Larger exposed air means largest UA (more heat transfer)  Fouling can affect performance over time (maintenance issues)  Interior and exterior fins on coils 19

Compressors  Purpose: to compress the refrigerant vapor to a

higher pressure (also increases the temperature)  Mechanical device: power input converted to mechanical energy  Types of Compressors: 

Positive-displacement: “squeeze”—increase pressure be decreasing vapor volume    



Reciprocating Rotary Scroll Trochoidal

Dynamic: “spin”—increase pressure by transferring angular momentum, momentum converted to pressure increase  Centrifugal



Centrifugal tend to be used in larger systems 20

Compressors (cont’d) Motor Types 





Open: motor and compression chamber separated via shaft link Hermetic: motor and compression chamber same, motor shaft and compressor crankshaft integral Semi-hermetic: bolted construction allows field service 21

Compression Cycle: Big Picture Direction of heat transfer

Cooling Tower

Expansion Valve

Condenser

Compressor

Evaporator

Air System

To Zones… Cooling Coil

22

Absorption-Based Liquid Chilling Systems  Concept 





Compression-based chillers use electrical energy (work) to produce heating or cooling (in the opposite direction of natural energy flow) Absorption-based chillers use mixture/solution chemistry and a heat source to produce heating (reverse cycle—also called heat transformer) or cooling (forward cycle—more common)\ Absorption-based systems are most effective when a “free” or very inexpensive source of heat is available  Solar energy  “Waste” heat  Heat source must be high enough quality (temperature) to drive system





No compressor or other large rotating mechanical equipment needed Two “refrigerants”—primary and secondary (absorbent)  Primary—usually water  Secondary—usually ammonia or lithium bromide (LiBr)

23

Absorption Chillers (cont’d)  Components        

Generator (desorber)—high pressure side Condenser—high pressure side Evaporator—low pressure side Absorber—low pressure side Heat Exchanger Pump Expansion valve/flow restrictors Refrigerants 24

Absorption Chillers (cont’d)  Cycle Details (LiBr system)  Pure water (vapor/liquid) in the condenser and evaporator  Primary refrigerant (water) and absorbent mixtures of varying concentrations in generator and absorber  Weak liquid solution is introduced into the generator along with heat from some source  Generator process: boils water out of solution accomplishing two things  Pure water vapor is sent over to condenser side of chamber  Strong(er) solution (liquid) is sent to absorber  Water vapor in condenser is converted to liquid (condensed) by the removal/rejection of heat

25

Absorption Chillers (cont’d)  Cycle Details (LiBr system, cont’d)  Condensed water is pushed to the evaporator as a result of the pressure difference/gravity  Liquid water in the evaporator is boiled off with the addition of heat at low temperature/pressure  Water vapor boiled off from evaporator is sent to absorber  Absorber: Water vapor condenses (potential heat rejection) and gets reabsorbed into the water-LiBr solution, weakening the solution  Absorber sends weakened solution back to generator where cycle starts over again  Pumps used to send solution from absorber to generator and to circulate liquid water over evaporator coil  Heat exchanger used between lines connection generator and absorber— reduces heat addition needed in generator (improving efficiency)  Goal is cooling at the evaporator (forward cycle) or heating at the generator (reverse cycle)  Many slight variations on this basic cycle

26

Absorption Chillers (cont’d)  Performance Issues  Capacities typically range from 180-almost 6000 kW (big!) though smaller units on the range of 18-35 kW available internationally  Typical COP values are much lower than for compression cycle chillers: 0.7-0.8 or lower is common  Low COP not necessarily a problem if heat source is free: COP = Usable cooling/energy input  Other Issues  Is a heat source available that can be used?  Concerns about water in contact with metal inside absorption system (rust formation)  Potential toxicity of absorbent  Noise—far less than a compression cycle chiller 27

Thermal Energy Storage  Concept 

Produce and store energy for use during another time

 Initially, this was as simple as cutting ice blocks from Lake Michigan and storing those until summer  Now, energy storage is produced during off-peak hours when energy costs are lower





Overall dollar effect is a reduction in the conditioning costs for the buildingprimary (or only) benefit is economic Reduction in cost per kW-hr and reduction in demand costs  Costs based on type of power plants running  Cost of start-up and shutdown of power plants

 

Mainly an issue for industrial customers, usually used for cooling Utilities have in the past actually paid (in part) for systems

 Reduced demand reduces need for new power plants  Shift of electric load uses power that might not otherwise be used (hydroelectric, nuclear, etc.)

28

Thermal Energy Storage (cont’d)  System Types  Tempered Water Storage  Storage of hot or cold water in a large tank above or below grade  Water is kept stratified, taking advantage of density differences of water at different temperatures  Inlet diffusers must be designed to avoid mixing  Some energy transfer does occur between hot and cold sides  Water in tank can serve as emergency water source in case of fire  Water temperatures for cooling same as for standard chiller only system  Large tank needs large space, tank losses 29

Thermal Energy Storage (cont’d)  System Types (cont’d) 

Ice Storage  Storage of cooling energy in the form of ice  Latent heat of solidification allows large amount

of energy storage in a much smaller area than a water system  System types:     

Ice-on-coil outside melt (obsolete) Ice-on-coil inside melt Encapsulated ice (ice container) Ice harvester Ice slurry

30

Thermal Energy Storage (cont’d)  Efficiency Issues (Ice Systems)  Process for producing ice less efficient than chilled water production (temperatures required for making ice are much lower, resulting in lower efficiency/COP and capacity of chiller)  This may be offset somewhat be reduced condenser temperatures due to cooler outdoor conditions at night  Systems can produce lower supply air temperatures, reducing the flow rates needed to provide same cooling (which lowers fan energy)  Do ice storage systems save dollars and energy? 31

Thermal Energy Storage Controls  Full Storage (discharging)  Minimizes on-peak energy consumption, maximizes energy consumption shift  Largest storage requirements and perhaps largest chiller (and initial costs)  Probably largest potential savings on operating costs  Partial Storage (discharging)  Types:

 Chiller priority: chiller runs during on-peak only up to some set demand limit, ice meets all other needs  Ice priority: storage meets demand up to some limit and chiller is turned on if the demand is higher than the limit





Some shift of energy consumption to off-peak, also savings on demand costs Smaller chiller requirements than full storage or no storage

32

Thermal Energy Storage Controls (cont’d)  Charging Strategies 



Zero prediction—chiller charges system at its capacity as soon as off-peak period starts “Optimal” strategies  Delay start of charging to take advantage of

presumably cooler outdoor air in early morning hours  And/or run chiller at less than full capacity at whatever its optimal fraction of full load is

33

Heating Equipment

Boiler Furnace Heat Pump

Heating Equipment Electric resistance heating Heat pump in heating mode Solar panels Boiler 

Water



Steam

same basic principle, just a different fluid

Furnace (air) 35

Boilers Definition: equipment whose sole

purpose is to provide hot water or steam for various uses within a building Size (capacity) range: 15 kW  30+ MW Fuels: coal, wood, fuel oil, (natural)

gas, electricity

36

Boiler Uses Steam:  Heating coils (reheat, preheat)  Hot water heat exchangers  Absorption cooling  Laundry  Sterilizers Water:  Heating coils (reheat, preheat)  Domestic hot water 37

water

water

water

water

Boilers: Basic Layout stack/flue/ Goal: chimney Try to get most efficient transfer of heat from flue gas (combustion products) to water burner air/fuel mix 38

Boiler Example (continued)

Digital image on this slide courtesy of: Lisa Fricker, Graduate Student, UIUC

39

Boilers: Types Dry Base/Back Wet Base/Back/Leg 

Base (bottom), back (with respect to multipass boilers), leg (top and sides)

Condensing 



Flue gas condensing due to low return temperature of water More efficient, but potential for rust greatly increased

40

Boilers: Efficiency Fuel Boiler (combustion efficiency) 

Efficiency = (input – stack loss) / input Non-condensing  75-86%



Condensing  88-95+%



Electric Boiler (overall efficiency)  

Efficiency = output / input Range of efficiencies  92-96% 41

Furnaces Heats air indirectly 

Combustion products do not mix with circulated air  dangerous

Fuels: 

Natural gas (most common)



LPG (liquefied petroleum gas)



Oil



Electric 42

Furnaces (continued) Sizes: 

Residential units (smallest) Commercial (44  600+ kW)



Generally smaller than boilers



Various configurations: 

Combustion systems



Air flow variations (single/multi-pass) 43

Furnace (AHU) Example

44

Boiler/Furnace Stack

45

Furnace Efficiency ANSI/ASHRAE Standard 103  Annual Fuel Utilization Efficiency (AFUE) Usable Heat Output AFUE ≈ Fuel Input 



AFUE includes: latent and sensible losses, cyclic effects, infiltration, pilot burner effects, and losses from a standing pilot when furnace not in use AFUE ≈ 78-80% for non-condensing, 90+% for condensing 46

Big Picture Review Zone (Loads)

mix box

air

supply fan

surroundings

Secondary System

heating coil

pump

A Building and its HVAC System

boiler Primary System

cooling coil pump

chiller pump

cooling tower 47

Summary Primary systems convert one form of

energy (fuel, electricity, etc.) to thermal energy Chillers/heat pumps are used to provide cooling (direct expansion or chilled water) Boilers are used to provide steam or hot water for heating coils Furnaces are used to provide hot air

48

Lecture 22: Primary System Loops in EnergyPlus





Water (fluid) side loop structures in EnergyPlus How to control fluid flow rates using the EnergyPlus pump strategies

2

Defining Loops Loops define the movement of mass

and energy within an HVAC system 

Plant loop



Condenser loop



Heat recovery loop

Systems defined by the order of

branches/components on the HVAC loop 3

Defining Loops (cont’d) Main loops divided into “sub-loops” or

“semi-loops” for organizational clarity & simulation logistics Sub-loops are matched pairs that consist of half of the main loop. For example, plant and condenser loops are broken into supply and demand sides. 4

Demand- & Supply-Side Sub-Loops Plant demand-side sub-loop contains

equipment that creates a load on the plant. Plant supply-side sub-loop contains equipment that meets these loads. Each supply-side sub-loop must be connected to a demand-side loop. 5

Demand- & Supply-Side Loops (cont’d) Heating Coil

HW Pump Outlet Node

±

Heating Coil Inlet Node

HW Demand Outlet Node Exit Pipe

Heating Coil Inlet Pipe Outlet Node HW Demand Inlet Node

HW Pump HW Supply inlet Node

Boiler Inlet Node Boiler

HW Supply Outlet Node

Boiler Outlet Node

HW Supply Outlet Pipe

Demand-Side Loop

Supply-Side Loop

6

Branches for Water-Side Loops Maximum Branch Flow Rate (Ignored) Comp1 Type Comp1 Name Comp1 Inlet Node Name Comp1 Outlet Node Name Comp1 Branch Control Type

7

Branches for Water-Side Loops - Example BRANCH, Heating Supply Inlet Branch,

!- Branch Name

,

!- Maximum Branch Flow Rate {m3/s}

PUMP:VARIABLE SPEED,

!- Comp1 Type

HW Circ Pump,

!- Comp1 Name

HW Supply Inlet Node,

!- Comp1 Inlet Node Name

HW Pump Outlet Node,

!- Comp1 Outlet Node Name

ACTIVE;

!- Comp1 Branch Control Type

8

Layout for Individual HVAC Supply or Demand Sub-Loops A

 Elements can be defined in

series, in parallel, or both with some restrictions  Branches are defined as individual legs within the loop structure  Segment between point A & B is defined as a branch, as is the section between points E and F

1 to m Components B n Splitter C1

Cn

...

1 to i Components D1

1 to j Components Dn

n Mixer E 1 to k Components F

9


 The first supply side

component between A & B must be the loop pump, which controls the loop flow.  There may be multiple branches between the splitter and mixer (between points C1 & D1 to Cn & Dn).  Each sub-loop may only have one splitter and one mixer.


Cn

...




10


 Equipment may be in

parallel between the mixer and splitter,  Within any branch, there can only be elements in series.  Sub-loops do not require a splitter or mixer, if all equipment on the sub-loop is in series—a single branch defines the entire sub-loop.


Cn

...




11

Pumping Rules Supply-Side Sub-Loop

 Pumps must be on the

supply side From DemandSide Sub-Loop  Pumps can operate as constant or variable flow  Pumps can run continuously or intermittently To DemandSide Sub-Loop

Loop Pump

Splitter

Components

Mixer

12

Pumping Rules (cont’d)  Single boiler/chiller with NO bypass,

PUMP:CONSTANT SPEED  

Boiler/chiller should be constant flow Pump should be intermittent

 Single boiler/chiller with NO bypass,

PUMP:VARIABLE SPEED 

Boiler/chiller should be variable flow, regardless of whether pump is intermittent or continuous (runs at the minimum if demand is less than minimum, this includes zero.) 13

Pumping Rules (cont’d) Single boiler/chiller with bypass,

PUMP:CONSTANT SPEED 

Boiler/chiller can be constant or variable flow



Pump may be intermittent or continuous as long as the bypass can handle the entire pump volume when the boiler is not operating 14

Pumping Rules (cont’d)  Multiple branches add more complexity, but it

is nothing more than continuity.  If the pump is putting out flow then it has to

have a branch to flow down whether it is a chiller or a bypass.

15

Pumping Rules (cont’d)  You are always safer adding the bypass for a

simulation. If the active machines require the flow the bypass will be dry  Thermodynamically it does not make any

difference if the flow goes through a machine that is OFF or it flows down the bypass.  There is no pressure simulation and flow

losses are not accounted for.

16

Summary of Loop Limitations  Each sub-loop allowed one splitter and one

mixer

 One bypass on each sub-loop optional  No other components may be in series with a

bypass

 Equipment may be in parallel only between

the splitter and mixer

 Equipment may be in series in each branch 17

3-Zone VAV System We are going to look at this system input Loop by Loop Outside Air


Supply Fan CW Pump

Bypass



Bypass

Chiller

Relief Air

VAV Box: ReHeat

North Zone

VAV Box: ReHeat

Return Hot

Water Mixer

Return Air Mixer

East Zone

Plant Demand Side Heating Loop

Hot Water Splitter

VAV Box: ReHeat

Zone Air Splitter

Resistive Zone

Condenser Bypass

Cond . Demand Side Loop Boiler Cond . Pump HW Pump

Condenser Bypass

Plant Supply Side Heating Loop Bypass

Cooling Tower

Cond . Supply Side Loop

18

Cooling Coil & Chilled Water Demand Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

Boiler Cond . Pump


Return Hot

VAV Box: ReHeat

North

Cond . Demand Side Loop

HW Pump

Water Mixer

Return Air Mixer

Splitter

East Zone

Hot Water

VAV Box: ReHeat

Zone Air Splitter

Zone


Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower


19

Cooling Coil & Chilled Water Demand Side CC

Cooling Coil Chilled Water Demand -Side Outlet Node Bypass Chilled Water Demand -Side Inlet Note

Objects required: 

BRANCH LIST



CONNECTOR LIST



SPLITTER



MIXER



BRANCH, VAV Sys 1 ChW-Branch  COIL:Water:DetailedFlatCooling, VAV SYS 1 Cooling Coil 20

Cooling Coil & Chilled Water Demand Side (cont’d) CC

Cooling Coil Chilled Water Demand -Side Outlet Node Bypass Chilled Water Demand -Side Inlet Note

Objects required (cont’d): 

BRANCH, Chilled Water Loop 1 CHW Inlet Branch  PIPE



BRANCH, Chilled Water Loop 1 CHW Outlet Branch  PIPE



BRANCH, Chilled Water Loop 1 CHW Bypass Branch  PIPE 21

Hot Water Demand Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

Boiler Cond . Pump


Return Hot

VAV Box: ReHeat

North

Cond . Demand Side Loop

HW Pump

Water Mixer

Return Air Mixer

Splitter

East Zone

Hot Water

VAV Box: ReHeat

Zone Air Splitter

Zone


Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower


22

Hot Water Coils & Demand Side 



 COIL:Water:SimpleHeating(3) 

BRANCH, HW Outlet Branch

HW Splitter



VAV Box: Reheat

VAV Box: Reheat

BRANCH, HW Inlet Branch



BRANCH, HW Bypass Branch

VAV Box: Reheat

Bypass

 PIPE

Return HW Mixer

 PIPE 

Zone Air Splitter



BRANCH LIST CONNECTOR LIST SPLITTER MIXER BRANCH,Zone X Reheat Branch (3)

Plant Demand Side



Heating Loop

Objects required:

 PIPE 23

Hot Water Loop Supply Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

VAV Box: ReHeat

North


Return Hot Water Mixer

Return Air Mixer

East Zone

Heating Loop

Hot Water Splitter

VAV Box: ReHeat

Zone Air Splitter

Zone

Plant Demand Side

Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower



24

Hot Water Loop Supply Side Hot Water Loop Supply Side

    

PLANT LOOP BRANCH LIST CONNECTOR LIST SPLITTER MIXER BRANCH, Supply Inlet Branch  PUMP:VARIABLE SPEED


Boiler Outlet Node Bypass




Objects required: Boiler Boiler Inlet Node

HW Supply Inlet Node HW Pump

HW Pump Outlet Node

25

Hot Water Loop Supply Side (cont’d) BRANCH, Boiler Branch  BOILER:SIMPLE 

BRANCH, Supply Bypass Branch  PIPE



BRANCH, Supply Outlet Branch


Boiler Boiler Inlet Node

HW Supply Inlet Node

 PIPE 

Boiler Outlet Node Bypass




Objects required:

PLANT OPERATION SCHEME

HW Pump HW Pump Outlet Node

 HEATING LOAD RANGE BASED OPERATION  HEATING LOAD RANGE EQUIPMENT LIST

26

Chilled Water Supply Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

VAV Box: ReHeat

North



Return Air Mixer

East Zone

Plant Demand Side

Hot Water Splitter

VAV Box: ReHeat

Zone Air Splitter

Zone

Heating Loop

Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower



27

Chilled Water Supply Side Plant Supply Side Cooling Loop

CW Pump Bypass

Plant Demand Side Cooling Loop

Chiller

Objects required:     

PLANT LOOP, Chiller Plant Chilled Water Loop BRANCH LIST CONNECTOR LIST SPLITTER MIXER 28

Chilled Water Supply Side (cont’d) Plant Supply Side Cooling Loop

CW Pump Bypass


Chiller


BRANCH, Chiller Plant Cooling Supply Inlet Branch  PUMP:VARIABLE SPEED



BRANCH, Chiller Plant Chiller Branch  CHILLER:Electric



BRANCH, Chiller Plant Cooling Supply Bypass Branch  PIPE 29

Chilled Water Supply Side (cont’d) Plant Supply Side Cooling Loop

CW Pump Bypass


Chiller


BRANCH, Chiller Plant Cooling Supply Outlet Branch  PIPE



PLANT OPERATION SCHEMES  COOLING LOAD RANGE BASED OPERATION  COOLING LOAD RANGE EQUIPMENT LIST

30

Condenser Loop Demand Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

VAV Box: ReHeat

North



Return Air Mixer

East Zone

Plant Demand Side

Hot Water Splitter

VAV Box: ReHeat

Zone Air Splitter

Zone

Heating Loop

Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower



31

Condenser Loop Demand Side Objects required:     

BRANCH LIST CONNECTOR LIST SPLITTER MIXER BRANCH, Condenser Demand Inlet Branch  PIPE



BRANCH, Chiller Condenser Branch


Chiller

Condenser Bypass

 CHILLER:Electric 

BRANCH, Cond. Demand Bypass Branch  PIPE



BRANCH, Cond. Demand Outlet Branch  PIPE

Condenser Supply Side Loop

32

Condenser Supply Side Outside Air


Supply Fan CW Pump


Bypass


Bypass

Chiller

Relief Air

VAV Box: ReHeat

North



Return Air Mixer

East Zone

Heating Loop

Hot Water Splitter

VAV Box: ReHeat

Zone Air Splitter

Zone

Plant Demand Side

Resistive

Condenser Bypass

Condenser Bypass


Cooling Tower



33

Condenser Supply Side Condenser Loop Supply Side Objects required:      

CONDENSER LOOP BRANCH LIST CONNECTOR LIST SPLITTER MIXER BRANCH, Supply Inlet Branch

Condenser Demand Side Loop

Condenser Pump Condenser Bypass

 PIPE 

BRANCH, Condenser Branch  COOLING TOWER:Single Speed

Cooling Tower

34

Condenser Loop Supply Side Condenser Supply Side (cont’d) Objects required (cont’d): 

BRANCH, Cond. Supply Bypass Branch  PIPE



BRANCH, Supply Output Branch  PIPE



Condenser Demand Side Loop

CONDENSER OPERATION SCHEMES  COOLING LOAD RANGE BASED OPERATION  LOAD RANGE EQUIPMENT LIST

Condenser Pump Condenser Bypass

Cooling Tower

35

Summary  Loops are backbone of HVAC simulation  all equipment attached to air or fluid loops  Loop structure permits assembly of any

system through input—not hardwired  Primary system may consist of four different loops: plant supply and demand, condenser supply and demand  Pumps regulate flow while attempting to meet requests on both sides of each loop pair  Individual loops may have components in series and parallel with some limitations

36

Lecture 23: Primary System Loops and Components



EnergyPlus loop controls Some of the many EnergyPlus plant and condenser components

2

Keywords Categories Covered in this Lecture  Plant Loop and Condenser Loop  Plant Operation Schemes, Cooling/Heating

Load Range Based Operation, Load Range Equipment List  Coil  Pump  Boiler  Chiller  Cooling Tower  Curve

3

Plant Loop IDD Description: Control information Flow and temperature limits for both sides of the loop Supply side nodes, branches, and connections Demand side nodes, branches, and connections Control information

PLANT LOOP, A1 , \field A2 , \field A3 , \field A4 , \field N1 , \field N2 , \field N3 , \field N4 , \field N5, \field A5, \field A6, \field A7, \field A8, \field A9, \field A10, \field A11, \field A12, \field A13; \field

Plant Loop Name Fluid Type (Water) Plant Operation Scheme List Name Loop Temperature Setpoint Schedule Name Maximum Loop Temperature in C Minimum Loop Temperature in C Maximum Loop Volumetric Flow Rate in m3/s Minimum Loop Volumetric Flow Rate in m3/s volume of the plant loop in m3 Plant Side Inlet Node Name Plant Side Outlet Node Name Plant Side Branch List Name Plant Side Connector List Name Demand Side Inlet Node Name Demand Side Outlet Nodes Name Demand Side Branch List Name Demand Side Connector List Name Load Distribution Scheme (Optimal|Sequential) 4

Plant Loop Limits Provides upper and lower boundaries

for temperature and flow rate Pump will operate within this range of flows (pump controls actual flow rate) Loop will not be allowed to vary temperature beyond temperature limits

5

Plant Loop Controls: Temperature  Setpoint temperature for plant loop can be

scheduled

 Plant loop will run equipment as needed and

as defined by the remaining controls to meet setpoint temperature

 If not enough equipment capacity, loop

setpoint temperature may not be met (can “catch-up” in future time steps)

 Pump controls will determine loop flow rate 6

Plant Loop Controls: Load Distribution  Sequential  Sequential simply operates equipment in a serial manner based on the loop operation scheme (which assigns priority to different equipment on the loop)  When highest priority equipment is out of capacity, next highest priority equipment tries to meet the load, etc.  Optimal  Parallel operation of equipment  Tries to find an “optimal” balance of the plant loop load between equipment based on the operating characteristics of the equipment on the loop  Not a strict optimization, simply an approximation at what might be the best load distribution from an energy perspective 7

Plant Loop Controls: Operation Scheme  List of load ranges that define which

equipment might try to meet a load  Requires following input: 





Plant Operation Schemes—a list of load range definitions and the schedules for when they are in effect Cooling/Heating Load Range Based Operation—a list of load ranges and the lists of equipment that are operating for those ranges Load Range Equipment List—the equipment lists referenced by the load ranges 8

Plant Loop Controls: Operation Scheme Example PLANT OPERATION SCHEMES, CW Loop Operation, LOAD RANGE BASED OPERATION, Peak Operation, On Peak, LOAD RANGE BASED OPERATION, Off Peak Operation, Off Peak;

Referenced in Plant Loop input !!!!!!!-

Plant Operation Scheme Name KEY--Control Scheme 1 Control Scheme Name 1 Control Scheme Schedule 1 KEY--Control Scheme 2 Control Scheme Name 2 Control Scheme Schedule 2

COOLING LOAD RANGE BASED OPERATION, Peak Operation, !- Name 0, !- Load Range Lower 70000, !- Load Range Upper Chiller Plant, !- Priority Control 70000, !- Load Range Lower 245000, !- Load Range Upper Chiller Plant and Purchased, !- Priority Control 245000, !- Load Range Lower 500000, !- Load Range Upper Purchased Only; !- Priority Control

Limit Limit Equip Limit Limit Equip Limit Limit Equip

1 {W} 1 {W} List Name 1 2 {W} 2 {W} List Name 2 3 {W} 3 {W} List Name 3

COOLING LOAD RANGE BASED OPERATION, Off Peak Operation, !- Name 0, !- Load Range Lower Limit 1 {W} 900000, !- Load Range Upper Limit 1 {W} All Chillers; !- Priority Control Equip List Name 1

9

Plant Loop Controls: Operation Scheme Example LOAD RANGE EQUIPMENT LIST, Chiller Plant, CHILLER:CONST COP, Little Chiller;

!- Equip List Name !- KEY--Plant Equip 1 Type !- Equip Name 1

LOAD RANGE EQUIPMENT LIST, Chiller Plant and Purchased, CHILLER:ELECTRIC, Big Chiller, Purchased:Chilled Water, Purchased Cooling;

!!!!!-

LOAD RANGE EQUIPMENT LIST, Purchased Only, Purchased:Chilled Water, Purchased Cooling;

!- Equip List Name !- KEY--Plant Equip 1 Type !- Equip Name 1

LOAD RANGE EQUIPMENT LIST, All Chillers, CHILLER:ELECTRIC, Big Chiller, CHILLER:CONST COP, Little Chiller;

!!!!!-

Equip List KEY--Plant Equip Name KEY--Plant Equip Name

Equip List KEY--Plant Equip Name KEY--Plant Equip Name

Name Equip 1 Type 1 Equip 2 Type 2

Name Equip 1 Type 1 Equip 2 Type 2

Load Range Equipment Lists referenced on previous slide

10

Example: Plant Loop PLANT LOOP, Chilled Water Loop, !- Plant Loop Name Water, !- Fluid Type CW Loop Operation, !- Plant Operation Scheme List Name CW Loop Temp Schedule, !- Loop Temperature Setpoint Schedule Name 98, !- Maximum Loop Temperature {C} 1, !- Minimum Loop Temperature {C} 0.0011, !- Maximum Loop Volumetric Flow Rate {m3/s} 0, !- Minimum Loop Volumetric Flow Rate {m3/s} autosize, !- volume of the plant loop {m3} CW Supply Inlet Node, !- Plant Side Inlet Node Name CW Supply Outlet Node, !- Plant Side Outlet Node Name Cooling Supply Side Branches, !- Plant Side Branch List Name Cooling Supply Side Connectors, !- Plant Side Connector List Name CW Demand Inlet Node, !- Demand Side Inlet Node Name CW Demand Outlet Node, !- Demand Side Outlet Nodes Name Cooling Demand Side Branches, !- Demand Side Branch List Name Cooling Demand Side Connectors, !- Demand Side Connector List Name Optimal; !- Load Distribution Scheme

11

Coils  COIL:Water:SimpleCooling  COIL:Water:SimpleHeating  COIL:Electric:Heating  COIL:Gas:Heating  COIL:Water:DetailedFlatCooling  COIL:DX:Cooling Bypass Factor-Empirical  Includes the condensing unit  COIL:DX:Heating-Empirical

12

Coil - Example Zone 1 Reheat Air Inlet Node Reheat Coil Zone 1 Zone 1 Reheat Air Outlet Node

Zone 1 Reheat Water Inlet Node Zone 1 Reheat Water Outlet Node

Supply Fan ZONE1

13

Coil – Example (cont’d) COIL:Water:SimpleHeating, Reheat Coil Zone 1, !Name of coil FanAndCoilAvailSched, !Coil Schedule 400.0, !UA of the Coil 1.3, !Max Water Flow Rate of Coil kg/sec Zone 1 Reheat Water Inlet Node, Zone 1 Reheat Water Outlet Node, !Coil Water Side Inlet & Outlet Node Zone 1 Reheat Air Inlet Node, Zone 1 Reheat Air Outlet Node; !Coil Air Side Inlet & Outlet Node

14

Pump – Example Circ Pump Plant Demand Side Cooling Loop

CW Supply Inlet Node


CW Pump Outlet Node Chiller 1

Chiller 2

Cond. Demand Side Loop

15

Pump – Example (cont’d)  PUMP:CONSTANT SPEED  PUMP:VARIABLE SPEED PUMP:VARIABLE SPEED, CW Circ Pump, !- Pump Name CW Supply Inlet Node, !- Inlet_Node CW Pump Outlet Node, !- Outlet_Node .0013, !- Rated Volumetric Flow Rate {m3/s} 300000, !- Rated Pump Head {Pa} 560, !- Rated Power Consumption {W} .87, !- Motor Efficiency 0.0, !- Fraction of Motor Inefficiencies to Fluid Stream 0, !- Coefficient1 of the Part Load Performance Curve 1, !- Coefficient2 of the Part Load Performance Curve 0, !- Coefficient3 of the Part Load Performance Curve 0, !- Coefficient4 of the Part Load Performance Curve 0, !- Min Flow Rate in variable flow capacity;{m3/s} INTERMITTENT; !- Pump Control Type 16

Boilers BOILER:SIMPLE WATERHEATER:SIMPLE 

Storage tank



Heat recovery

PURCHASED:HOT WATER

17

Boiler - Example Heating Coil

± HW Pump Plant Supply Side Heating Loop


Boiler Inlet Node Boiler Boiler Outlet Node

18

Boiler – Example (cont’d) BOILER:SIMPLE, Boiler Plant Boiler,! Boiler Name GAS, ! Fuel Type 25000, ! Nominal Capacity {W} 0.8, ! Theoretical Boiler Efficiency 100, ! Design Boiler Water Outlet Temp {C} 0.0021, ! Max Design Boiler Water Flow Rate {m3/s} 0.10, ! Minimum Part Load Ratio 1.00, ! Maximum Part Load Ratio 1.00, ! Opt Part Load Ratio 1.0, ! Coefficient1 of the fuel use/part load ratio curve 0.0, ! Coefficient2 of the fuel use/part load ratio curve 0.0, ! Coefficient3 of the fuel use/part load ratio curve Boiler Inlet Node, ! Boiler_Water_Inlet_Node Boiler Outlet Node, ! Boiler_Water_Outlet_Node 100, ! Temp Upper Limit Water Outlet {C} ConstantFlow; ! Boiler Flow Mode (v1.0.1)

19

Chillers  CHILLER:ELECTRIC  CHILLER:GAS TURBINE  CHILLER:ABSORPTION  CHILLER:GAS ABSORPTION  Direct-Fired Gas Absorption Chiller-Heater  CHILLER:CONST COP  CHILLER:ENGINEDRIVEN  PURCHASED:CHILLED WATER

20

Chiller – Example Plant Demand Side Cooling Loop


CW Pump

Chiller Inlet Node Chiller

Chiller Outlet Node

Chiller Condenser Outlet Node

Chiller Condenser Inlet Node

Condenser Demand Side Loop 21

Chiller – Example (cont’d) CHILLER:ELECTRIC, Big Chiller, !- Chiller Name WATER COOLED, !- Condenser Type 100000, !- Nominal Capacity {W} 2.75, !- COP Big Chiller Inlet Node, !- Plant_Side_Inlet_Node Big Chiller Outlet Node, !- Plant_Side_Outlet_Node Big Chiller Condenser Inlet Node, !- Condenser_Side_Inlet_Node Big Chiller Condenser Outlet Node, !- Condenser_Side_Outlet_Node .15, !- Minimum Part Load Ratio 1.0, !- Maximum Part Load Ratio .65, !- Opt Part Load Ratio 35.0, !- Temp Design Condenser Inlet {C} 2.778, !- Temp Rise Coefficient 6.67, !- Temp Design Evaporator Outlet {C} 0.0011, !- Design Evaporator Vol Water Flow Rate {m3/s} (v1.0.1) 0.0011, !- Design Condenser Volumetric Water Flow Rate

22

Chiller – Example (cont’d) 0.9949, -0.045954, -0.0013543, 2.333, -1.975, 0.6121, 0.03303, 0.6852, 0.2818, 5; ConstantFlow;

!!!!!!!!!!!-

Coefficient1 of the capacity ratio curve Coefficient2 of the capacity ratio curve Coefficient3 of the capacity ratio curve Coefficient1 of the power ratio curve Coefficient2 of the power ratio curve Coefficient3 of the power ratio curve Coefficient1 of the full load ratio curve Coefficient2 of the full load ratio curve Coefficient3 of the full load ratio curve Temp Lower Limit Evaporator Outlet {C} Chiller Flow Mode (v1.0.1)

2 AvailToNominalCapacityRatio = C1 + C2 ∆temp + C3 ∆temp

FullLoadtoPowerRatio = C1 + C2 AvailToNominalCapRatio + C3 AvailToNominalCapRatio 2

FracFullLoadPower = C1 + C2 PartLoadRatio + C3 PartLoadRatio 2 Power = FracFullLoadPower ∗ FullLoadtoPowerRatio ∗

Q evaporator COP

23

Cooling Tower – Example Plant Supply Side Cooling Loop Condenser Tower Outlet Node

Cond Demand Side Loop

Condenser Tower Inlet Node

Tower

24

Cooling Tower – Example (cont’d) COOLING TOWER:TWO SPEED COOLING TOWER:SINGLE SPEED 

2 Input Methods  UA and Design Water Flow Rate

COOLING TOWER:SINGLE SPEED, Big Tower1, !- Tower Name Condenser Tower 1 Inlet Node, !- Water Inlet Node Name Condenser Tower 1 Outlet Node, !- Water Outlet Node Name .0011, !- Design Water Flow Rate {m3/s} 8.0, !- Design Air Flow Rate {m3/s} 500, !- Fan Power at Design Air Flow Rate {W} 175.0, !- Tower UA Value at Design Air Flow Rate {W/K} 0.0, !- Air Flow Rate in Free Convection Regime {m3/s} 0.0, !- Tower UA Value at Free Convection Air Flow Rate {W/K} UA and Design Water Flow Rate; !- Tower Performance Input Method 25

Cooling Tower – Example (cont’d) 

2 Input Methods (Cont.)  Nominal Capacity

COOLING TOWER:SINGLE SPEED, Big Tower1, !- Tower Name Condenser Tower 1 Inlet Node, !- Water Inlet Node Name Condenser Tower 1 Outlet Node, !- Water Outlet Node Name , !- Design Water Flow Rate {m3/s} autosize, !- Design Air Flow Rate {m3/s} 500, !- Fan Power at Design Air Flow Rate {W} , !- Tower UA Value at Design Air Flow Rate {W/K} 0.0, !- Air Flow Rate in Free Convection Regime {m3/s} 0.0, !- Tower UA Value at Free Convection Air Flow Rate {W/K} Nominal Capacity, !- Tower Performance Input Method 20438., !- Tower Nominal Capacity {W} 0.; !- Tower Free Convection Capacity {W}

26

Curve Objects CURVE:CUBIC CURVE:QUADRATIC CURVE:BIQUADRATIC CURVE:BIQUADRATIC, Sample Curve, 1.000, 0.100, 0.001, 0.200, 0.002, 0.003, 0, 100, 0, 100;

!!!!!!!!!!!-

Name Coeff1 Constant Coeff2 x Coeff3 x**2 Coeff4 y Coeff5 y**2 Coeff6 x*y minimum value of maximum value of minimum value of maximum value of

x x y y 27

Summary  Each component on the primary system loops

has specific input requirements that are unique to that component type  Some components may link between two different loops, for example: 



Coils—air/zone equipment loop and plant demand side Chiller—plant supply side and condenser demand side

 Primary loops have temperature, flow, and

operational controls that must be defined by the program user

28

Lecture 24: Ground Heat Transfer


Importance of this Lecture to the Simulation of Buildings  Almost all buildings have some connection to

the ground  Depending on the building type, ground heat transfer may play a significant role in determining the response of the building to its surroundings  Ground heat transfer is often difficult to calculate and often miscalculated  Better simulation tools can help avoid errors in predicting the effects of the ground on the building 2


Ground heat transfer in EnergyPlus How to use the slab.exe utility program to obtain better ground heat transfer evaluation in EnergyPlus

3

Keywords Covered in this Lecture GroundTemperatures Inputs specific to the slab.exe utility

program

4

Ground Heat Transfer Introduction  It is difficult to link ground heat transfer calculations

to EnergyPlus since the conduction calculations in EnergyPlus are one-dimensional and the ground heat transfer calculations are two or three-dimensional  This causes severe modeling problems for the ground heat transfer calculation. But, it is necessary to be able to relate ground heat transfer calculations to that model  Note that ground heat transfer is highly dependent on soil properties and that soil properties can vary greatly from location to location—even between locations in the same city 5

Ground Temperature Object Specifies the outside surface temp for

surfaces in contact with the ground (e.g., slab floors, basement walls)

GROUNDTEMPERATURES, 12.2, 12.7, 12.7;

!- Jan {C} !- Feb {C} !- Dec {C}

6

Ground Temperatures (cont’d)  Three sets of ground temperatures are tabulated in

the weather file.  Ground temperatures are for “thermally undisturbed” soil with a diffusivity of 2.3225760E-03 {m**2/day}. - Monthly Calculated "undisturbed" Ground Temperatures ° Jan Feb Mar Apr May Jun Jul Aug Sep 0.5 m 9.8 9.5 10.1 11.5 13.4 15.1 16.3 16.7 16.0 2.0 m 11.0 10.4 10.6 11.4 12.6 14.0 15.1 15.7 15.6 4.0 m 12.0 11.4 11.3 11.6 12.4 13.3 14.2 14.8 14.9

Oct Nov Dec 14.6 12.8 11.0 14.8 13.5 12.1 14.5 13.8 12.8

 These values are not appropriate for computing

building floor losses.

7

Ground Temperatures (cont’d)  Use slab.exe utility to compute appropriate

ground temperatures at the exterior side of any surface that is in contact with the ground. 



This is a monthly value that establishes the outside boundary condition (temperature) for a particular surface in contact with the ground. Documentation for slab.exe can be found in AuxiliaryPrograms.pdf .

 Otherwise, take the indoor air temperature

and subtract 2C as a reasonable starting value to use for most commercial applications in the U.S. 8

Ground Temperatures (cont’d) Slab.exe utility will calculate:  Monthly core, perimeter, and average ground temperatures  Given a description of the floor slab, perimeter insulation, the average indoor temperature, the soil conditions and the weather file for a given location  Will only compute temperatures for slabon-grade construction (i.e., not basements) 9

PreProcess Folder PreProcess  BLAST Translator  DOE-2 Translator  IDF Editor  IFCtoIDF  Weather Converter  Ground Temp Calculator 10

Ground Temperatures (cont’d) Slab.exe ground temperature utility

11

Slab.exe Utility Program The slab program used to calculate the

results is included with the EnergyPlus distribution. It requires an input file named GHTin.idf in the input data file format. The needed corresponding idd file is E+SlabGHT.idd. An EnergyPlus weather file for the location is also needed. A sample batch file is shown on the next slide. 12

Slab.exe Batch File Basic Functions echo ===== %0 (Run Slab Generation) ===== Start ===== : Complete the following path and program names. : path names must have a following \ or errors will happen set program_path= set program_name=Slab.exe set input_path= set output_path= set weather_path= IF EXIST %output_path%%1.gtp ERASE %output_path%%1.gtp IF EXIST %output_path%%1.ger ERASE %output_path%%1.ger copy %input_path%%1.idf GHTIn.idf if EXIST %weather_path%%2.epw copy %weather_path%%2.epw in.epw ECHO Begin Slab processing . . . %program_path%%program_name% IF EXIST "SLABSurfaceTemps.txt" MOVE "SLABSurfaceTemps.txt" %output_path%%1.gtp IF EXIST eplusout.err MOVE eplusout.err %output_path%%1.ger ECHO Removing extra files . . . IF EXIST GHTIn.idf DEL GHTIn.idf IF EXIST in.epw DEL in.epw

13

Ground Slab Heat Transfer  The simulation can go from a 1 to x (user

specified) years and uses an explicit finite difference solution technique.  Uses monthly average inside temperatures.  Can use a daily cyclic hourly variation of inside temperatures; main purpose is for user experimentation.  Will shortly have multiple ground temperature capability in EnergyPlus 14

Slab Program Input ! =========== Materials, 2, 0.158, 0.379, 0.9, 0.9, 0.75, 0.03, 6.13, 9.26;

ALL OBJECTS IN CLASS: MATERIALS =========== ! ! ! ! ! ! ! ! !

N1 N2 N3 N4 N5 N6 N7 N8 N9

[NMAT: Number of materials: 2] [ALBEDO: Surface Albedo: No Snow: 0-1] [ALBEDO: Surface Albedo: Snow: 0-1] [EPSLW: Surface Emissivity: No Snow: 0.9] [EPSLW: Surface Emissivity: Snow: 0.9] [Z0: Surface Roughness: No Snow: 0-10 cm] [Z0: Surface Roughness: Snow] [HIN: Indoor HConv: Downward Flow: 4-10 W/m**2-K] [HIN: Indoor HConv: Upward: 4-10 W/m**2-K]

15

Slab Program Input (Cont.) ! =========== MatlProps, 2300, ! 1200, ! 653, ! 1200, ! 0.93, ! 1; !

ALL OBJECTS IN CLASS: MATLPROPS =========== N1[RHO: Slab Material density: Validity: 2300.0 kg/m**3] N2[RHO: Soil Density: 1200.0 kg/m**3] N3[CP: Slab CP: Validity: 650.0 J/kg-K] N4[CP: Soil CP: Validity: 1200.0 J/kg-K] N5[TCON: Slab k: Validity: .9 W/m-K] N6[TCON: Soil k: Vailidity: 1.0 W/m-K]

! =========== BoundConds, ! A1 TRUE, TRUE, ! A2 FALSE; ! A3

ALL OBJECTS IN CLASS: BOUNDCONDS =========== [EVTR: TRUE/FALSE: Is surface evapotranspiration modeled] [FIXBC: TRUE/FALSE: Is the lower boundary at a fixed temp.] [OLDTG: TRUE/FALSE: is there an old ground temperature file]

16

Slab Program Input (Cont.) ! =========== ALL OBJECTS IN CLASS: BLDGPROPS =========== BldgProps, 2, ! N1[IYRS: Number of years to iterate: 10] 0, ! N2[Shape: Slab shape: 0 ONLY] 3.048, ! N3[HBLDG: Building height 0-20 m] 21.4; ! N4[TIN: Indoor temperature set point: 21 C]

! =========== ALL OBJECTS IN CLASS: INSULATION =========== Insulation, 0., ! N1[RINS: R value of under slab insulation 0-2.0 W/m-K] 0., ! N2[DINS: Width of strip of under slab insulation 0-2.0 m] 2.0, ! N3[RVINS: R value of vertical insulation 0-3.0 W/m-K] 1.0, ! N4[ZVINS: Depth of vertical insulation .2 .4 .6 .8 1.0 ! 1.5 2.0 2.5 3.0 m ONLY] 1; ! N5[IVINS: Flag: Is there vertical insulation 1=yes 0=no]

17

Slab Program Input (Cont.) ! =========== ALL OBJECTS IN CLASS: EQUIVSLAB =========== EquivSlab, 5.08, ! N1[APRatio: The area to perimeter ratio for this slab: m] TRUE; ! A1[EquivSizing: Flag: Will the dimensions of an equivalent ! slab be calculated (TRUE) or will the dimensions be input ! directly? (FALSE)] ! =========== ALL OBJECTS IN CLASS: EQUIVAUTOGRID =========== EquivAutoGrid, ! NOTE:EquivAutoGrid only necessary when EquivSizing is true 0.1016, ! N1[SLABDEPTH: Thickness of slab on grade, 0.1 m] 15; ! N2[CLEARANCE: Distance from edge of slab to domain edge, 15.0 m] ! =========== ALL OBJECTS IN CLASS: AUTOGRID =========== AutoGrid, ! NOTE: AutoGrid only necessary when EquivSizing is false , ! N1[SLABX: X dimension of the building slab, 0-60.0 m] , ! N2[SLABY: Y dimension of the building slab, 0-60.0 m] , ! N3[SLABDEPTH: Thickness of slab on grade, 0.1 m] ; ! N4[CLEARANCE: Distance from edge of slab to domain ! edge, 15.0 m]

18

Building Properties IDD Object Slab Program uses the EnergyPlus input philosophy and uses its own IDD. Example is shown below: BldgProps, N1, ! [IYRS: Number of years to iterate: 10] N2, ! [Shape: Slab shape: 0 ONLY] N3, ! [HBLDG: Building height 0-20 m] N4, ! [TIN1: Indoor Average temperature set point for January: 22 C] N5, ! [TIN2: Indoor Average temperature set point for February: 22 C] N6, ! [TIN3: Indoor Average temperature set point for March: 22 C] N7, ! [TIN: Indoor Average temperature set point for April: 22 C] N8, ! [TIN: Indoor Average temperature set point for May: 22 C] N9, ! [TIN: Indoor Average temperature set point for June: 22 C] N10, ! [TIN: Indoor Average temperature set point for July: 22 C] N11, ! [TIN: Indoor Average temperature set point for August: 22 C] N12, ! [TIN: Indoor Average temperature set point for September: 22 C] N13, ! [TIN: Indoor Average temperature set point for October: 22 C] N14, ! [TIN: Indoor Average temperature set point for November: 22 C] N15, ! [TIN: Indoor Average temperature set point for December: 22 C] N16, ! [Daily sine wave variation amplitude: 0 C ] N17; ! Convergence Tollerance : 0.1

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Variable Inside Temperature Monthly Slab Outside Face Temperatures, C Perimeter Area: 304.00 Core Area: 1296.00 Month Average Perimeter Core Inside 1 17.67 16.11 18.03 18.0 2 17.45 15.92 17.81 18.0 3 17.43 16.07 17.74 18.0 4 19.00 17.82 19.27 20.0 5 19.24 18.23 19.48 20.0 6 19.31 18.42 19.52 20.0 7 20.92 20.14 21.11 22.0 8 21.17 20.44 21.35 22.0 9 21.22 20.45 21.40 22.0 10 21.21 20.26 21.44 22.0 11 19.62 18.54 19.88 20.0 12 19.35 17.99 19.67 20.0 20

Heat Fluxes Temperatures Month 1 2 3 4 5 6 7 8 9 10 11 12

Heat Flux W/m^2

Average Perimeter Core Inside Perimeter 17.67 16.11 18.03 18 7.00 17.45 15.92 17.81 18 7.70 17.43 16.07 17.74 18 7.15 19 17.82 19.27 20 8.07 19.24 18.23 19.48 20 6.56 19.31 18.42 19.52 20 5.85 20.92 20.14 21.11 22 6.89 21.17 20.44 21.35 22 5.78 21.22 20.45 21.4 22 5.74 21.21 20.26 21.44 22 6.44 19.62 18.54 19.88 20 5.41 19.35 17.99 19.67 20 7.44

Average 1.22 2.04 2.11 3.70 2.81 2.56 4.00 3.07 2.89 2.93 1.41 2.41 21

Heat Fluxes with Hourly Variation of Inside Temp Month 1 2 3 4 5 6 7 8 9 10 11 12

Average Perimeter

Core

Inside

Perimeter Average Heat Flux Heat Flux W/m^2 W/m^2

17.51

16.03

17.86

18

7.30

1.81

17.29

15.85

17.63

18

7.96

2.63

17.27

16

17.57

18

7.41

2.70

18.87

17.77

19.13

20

8.26

4.19

19.11

18.16

19.34

20

6.81

3.30

19.17

18.34

19.37

20

6.15

3.07

20.81

20.07

20.98

22

7.15

4.41

21.05

20.36

21.21

22

6.07

3.52

21.09

20.38

21.26

22

6.00

3.37

21.08

20.19

21.29

22

6.70

3.41

19.47

18.45

19.71

20

5.74

1.96

19.2

17.92

19.51

20

7.70

2.96

22

Hourly Temperature Variation Slab with Sinusoidal Inside Temp

20 Perim Out Ts

15

Core Out Ts 10

Inside Temp

5

23

21

19

17

15

13

11

9

7

5

3

0

1

Temperature, C

25

hour 23

General Procedure for using slab.exe with EnergyPlus 1.

Run the building in EnergyPlus with an insulated slab or as a partition to obtain monthly inside temperatures.

2.

Put those monthly inside temperatures in the slab program to determine outside face temperatures.

3.

Use resulting outside face temperatures in EnergyPlus.

4.

Repeat 2 and 3 if inside temperatures change significantly. 24

Example Results 100 X 300 ft Warehouse, Minneapolis

25

Slab Results Month Average Perimeter Core 1 4.78 3.90 4.99 2 4.68 3.85 4.87 3 6.13 5.40 6.30 4 10.54 9.90 10.69 5 17.56 16.83 17.73 6 22.56 21.73 22.75 7 24.96 24.14 25.16 8 24.31 23.51 24.50 9 20.03 19.33 20.19 10 12.89 12.31 13.03 11 7.07 6.56 7.19 12 5.17 4.51 5.33

Inside 4.4 4.5 6.3 11.8 20.0 25.1 27.1 25.6 20.1 11.9 5.8 4.4

Convergence has been gained. 26

Temperature Differences between EnergyPlus Runs Inside Temperature Difference, Step 2 to step 3 0.3 0.2 0.1 0 -0.1

1

2

3

4

5

6

7

8

9

10

11

12

-0.2 -0.3 -0.4 -0.5 -0.6 -0.7 month

27

Summary Almost all buildings have some thermal

connection to the ground, but ground heat transfer can be difficult to simulate Slab Program allows more accurate calculation of ground temperatures for use with EnergyPlus Use of Slab Program—EnergyPlus combination may require iteration between the two programs

28

EnergyPlus University Course

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