Induction Course for new M & E Engineers Air-Conditioning and Mechanical Ventilation 21st September 2013 Ir. NG YONG KONG, P.Eng., GBIF, MASHRAE Email:
[email protected] Tel: +6012 – 201 201 9319
1.ASHRAE Handbook – Handbook – SI SI and Imperial Units a.Fundamentals 2013 b.HVAC Systems and Equipment 2012 c.HVAC Applications 2011 d.Refrigeration 2010 2. Air Conditioning System Design - CARRIER 3. Handbook of A/C Design – Design – TRANE TRANE 4. CIBSE 5. MS 1525:2007 COP on Energy Efficiency and Use of Renewable Energy for Non-Residential Buildings ( 1 st Revision) 5. Uniform Building By – By – Laws 1984 (UBBL) 6. Guide to Fire Protection in Malaysia
1.ASHRAE Handbook – Handbook – SI SI and Imperial Units a.Fundamentals 2013 b.HVAC Systems and Equipment 2012 c.HVAC Applications 2011 d.Refrigeration 2010 2. Air Conditioning System Design - CARRIER 3. Handbook of A/C Design – Design – TRANE TRANE 4. CIBSE 5. MS 1525:2007 COP on Energy Efficiency and Use of Renewable Energy for Non-Residential Buildings ( 1 st Revision) 5. Uniform Building By – By – Laws 1984 (UBBL) 6. Guide to Fire Protection in Malaysia
INDUCTION COURSE IN AIR-CONDITIONING 1) 2) 3) 4) 5) 6) 7) 8) 9)
INTR NTRODUCTI CTION TO AIR-CO R-COND NDIITIO TIONIN NING PRINCIPLES OF REFRIGERATION PSYCHROMETRICS COO COOLING ING LO LOAD ES ESTIMA TIMAT TION ION & SOFTW FTWARE ARE REFRIGERANT IS ISSUE TYPES YPES OF AIR AIR COND CONDIT ITIO IONI NING NG SY SYST STE EMS AHRI AH RI 550 50/5 /590 90 or MS2 S24449 FOR FOR CHI CHILLER LLERS S MS1525:2007 Gre reeen Building In Index ( GBI )
1.) Introduction to Air Conditioning What is Comfort? Definition: A State of Ease and Contentment” • “A satisfying and enjoyable experience” The feeling of comfort is clearly subjective. Main components that determine comfort : • • • •
Climatic conditions Outdoor environment Indoor environment Activities & clothing
Comfort Requirements •
Temperature
•
Humidity
•
Air movement
•
Fresh air
•
Clean air
•
Noise level
•
Lighting
•
Furniture and work surfaces
ASHRAE Standard 55-2010 Specifies conditions likely to be thermally acceptable to at least 80% of the adult occupants in a space
Design to ASHRAE 55-2010 : Thermal Environmental Conditions for Human Occupancy in conjunction relevant localised parameters as listed in MS 1525:2007 Specifies Conditions likely to be thermally acceptable to at least 80% of the adult occupants in a space 6 Primary factors that must be addressed when defining conditions for thermal comfort are: 1.) Metabolic rate 2.) Clothing insulation 3.) Air temperature 4.) Radiant temperature 5.) Air speed 6.) Humidity
2. What is a Refrigerant? A refrigerant is a fluid that absorbs heat and changes from vapor to liquid phase at reasonable pressures and temperatures as encountered in mechanical refrigeration.
Principles of R efrig eration • The science of refrigeration is based upon the fact that a liquid can be vaporised at any desired temperature by changing the pressure on it. • Liquids boiling at low temperatures (Refrigerants) are the most desirable medium for removing heat. • The large quantities of heat is absorbed when liquid is evaporated (Changed to vapour).
2.What is a Refrigerant . PRESSURE psia HCFC-22
HFC-410A
CO2
Propane
0.00186
15.26
26
7.43
145.77
16.1
0
0.0185
38.73
64
21.62
305.80
38.4
40
0.122
82.28
132
49.70
567.50
78.6
100
0.950
210.70
340
138.80
X
188.6
130
2.225
311.60
500
213.40
X
273.3
212
14.696
*CP
*CP
587.20
X
X
F -40
Water
*Critical Point, pressure psia
HFC-134a
Four Laws of System Operation 1. Heat only moves from a higher temperature to a lower temperature 2. A large amount of energy is required to change the state of matter 3. The temperature and energy required to change state are a function of pressure 4. Fluid flow only occurs if a pressure difference exists
Three Types of Heat Transfer Conduction Conduction – Transfer by contact
Convection – May be natural or forced transfer by density currents and fluid motion
Radiation – Transfer by electromagnetic waves
Mechanical refrigeration uses the first two.
Sensible Heat Btu is the heat energy necessary to change one pound of water by 1 Btu – British thermal unit
1 F RISE
1 ton = 12,000 Btu/Hr. = 3.517 kWr
1 lb 1 Btu
F
°
Latent Heat Total Heat = Sensible Heat + Latent Heat 212
F
°
212
F
°
Not measured on a thermometer
Change of State
Refrigeration Cycle • The refrigeration can be obtained by use of the refrigerants. • When the liquid refrigerants are allowed to expose to the atmosphere, it evaporates and refrigeration can be obtained. • To make use of the vaporised refrigerant over and over again it is necessary to use the devices like evaporator, compressor and condenser.
Four Components Are Required
3. Heat rejecting section 4. Pressure/ flow control valve
1. Heat absorbing section
2. Vapor pump
Basic System Components Condenser
Air out: 115
F db
°
108 F 274.7 psia
120 F 274.7 psia
°
°
SCT
SDT Air in: 95
F
°
SST F db / 57.3
°
F wb
°
55 F 90.8 psia °
45 F 90.8 psia °
Evaporator
SET Air in: 80
F db / 67
°
Evaporator Compressor
Compressor
Air out: 59.7
Every system has four basic components
F wb
°
Condenser Rejects the heat from the load and system losses Highly superheated refrigerant condenses in the tubes as heat load is rejected and changes back to a liquid and is subcooled
Why Study Psychrometrics? 1. Determine the temperature at which condensation will occur in walls or on a duct 2. Find all the properties of air by knowing two conditions 3. Calculate the required airflow to the space and for the equipment 4. Determine the sensible and total cooling load the unit should provide 5. Determine the coil depth and temperature to meet the design load conditions Brooklyn Printing Plant
Objectives •
•
•
•
•
Understand the properties of air and water vapor mixtures Build the psychrometric chart Use the psychrometric chart to determine the properties of an air/water vapor mixture Use the psychrometric chart to understand the basic air conditioning processes Understand how the processes can be combined into a system using a system plot diagram and psychrometric chart
Dry-Bulb Thermometer
The temperature of air as measured by a thermometer with a dry sensing bulb
Wet-Bulb Thermometer
The temp. at which water will evaporate into the air sample.
Physically…the temp. of air when measured by a thermometer with a wetted wick over the sensing bulb.
Relative Humidity ( RH )
50%
100% (saturated)
If RH of the air is 50%, it contains one-half the amount of moisture possible at the existing dry-bulb temperature.
Relative Humidity
Relative Humidity
Amount of moisture that a given =
amount of air is holding Amount of moisture that a given amount of air can hold
At the same dry-bulb temperature.
The amount of water vapour in the air, compared to it’s maximum capacity at that dry bulb temperature.
Dry Bulb Temperature Scale
wb dp F °
db
F
°
Psychrometric Chart Enthalpy
Specific Volume Relative Humidity
Wet Bulb Temperature Dew Point Temperature
Specific Humidity
wb dp F °
db
F
°
Dry Bulb Temperature
Sensible Heat qs
1.10 cfm t
db wb dp gr -
Changes Changes Constant Constant
68% rh
COOLING
52 gr
HEATING wb dp F
90 – 60 = 30
°
db
24% rh
F
t
°
60
°
90
°
Sensible Heat Change
Latent Heat q l
0.69
wb dp gr db -
cfm
grains
Changes Changes Changes Constant
68% rh C o n d e n s a t i o n
E v a p o r a t i o n
wb dp F °
db
F
°
75
°
24% rh
grains
89 – 30 = 60
89 gr Latent Heat Change
30 gr
Enthalpy Scale hs = Enthalpy at saturation hs = 27.5 Btu/lb
wb dp F °
db
F
°
Relative Humidity Lines Relative Humidity Approx.
60
132
45% 132 gr
45%
60 gr
wb dp F °
db
F
°
75
°
Dew Point Example 95 F db 100 gr °
100 gr
wb dp F °
db
F
°
55
°
67
°
95
°
Air Conditioning Processes 1. Sensible Heating 2. Sensible Cooling 3. Humidification 4. Dehumidification 5. Cooling and Humidification (Evaporative Cooling) 6. Cooling and Dehumidification 7. Heating and Humidification 8. Heating and Dehumidification wb dp F °
db
F
°
Total Heat qt
qs
ql
Cooling
wb dp F
n o i t a s n e d n o C
°
db
s n i a r G
t
E v a p o r a t i o n
Heating
F
°
75
°
95
°
Sensible Heat Change
89 gr Latent Heat Change
30 gr
Using Enthalpy to Determine Total Heat Removed
Latent Heat 1.7
Sensible Heat 5.0 wb dp F °
db
F
°
55
°
75
°
Total Capacity or Load Formula
GTH = 4.5 cfm
h
Where: GTH 4.5 cfm h
= = = =
Grand Total Heat Constant cubic feet per minute Difference in enthalpy from air entering to air leaving conditions
Cooling Coils Face Area = Length Height Length
Height
Velocity cfm / face area
Rows
Fins Refrigerant Temperature
ASHRAE Comfort Zone
4.) Cooling Load Estimation To design the effective HVAC design, the analysis of heat load is carried out. Cooling Load Components: - Location/altitude/ orientation Transmission through Building Components walls, glass, ceilings, roofs, doors and floors, partitions from non conditioned spaces. •
•
Solar Radiations on - glass, wall, roof, etc.
Human Comfort - Design •
Ventilation Requirements.
•
Latent and Sensible heat losses from people.
•
Lighting and ballasts.
•
Appliances and equipment in the conditioned space.
•
Ducts and motor heat gain from cooling system itself.
•
Infiltration of outdoor air.
7.) TYPES OF AIR CONDITIONING SYSTEMS WRAC
•
•
WRACs are factory-made assemblies that normally include an evaporator or cooling coil and a compressor-condenser combination Room Air Conditioners are encased assemblies designed primarily for mounting in a window or through a wall and are often called Window Room Air Conditioners ( WRAC ).
Window Room Air Conditioner
Window room air conditioner
Air Cool Split Units •
•
•
A Unitary Air Conditioner with more than one factory-made assembly is commonly called a split system. It basically comprises an indoor unit with the evaporator and blower and an outdoor unit with the compressor, condenser coil and fan coupled with refrigeration piping. The indoor units is often known as Fan Coil Units ( FCUs )and the outdoor units known as Condensing Units. As a whole, they are known as the Air Cooled Split Units. (ACSUs)
3. Air Cooled Split Units The installation of an Air Cooled Split Unit is basically the same with the outdoor and indoor units connected with refrigerating piping called Suction and Liquid line. Manufacturers recommend a Maximum Piping length of 7 to 15 m and maximum elevation between indoor and outdoor unit of 5 to 7 m.
3. Air Cooled Split Units Warm air (recirculating)
Fan Coil Unit Cool air
Outdoor air
Condensing Unit
3.Air Cooled Split Units (ACSUs) Both indoor and outdoor units are housed in robust casings. The outdoor unit is basically the same construction for all the various types of indoor units. The difference lies in the type of indoor unit. Wall Mounted
Floor Standing
Cassette
Ceiling Exposed
3. ACSUs : Fresh Air Intake ?
The wall mounted and under ceiling split system has no provision for intake of outdoor air and/or exhaust of stale room air. Room air is just . filtered and recirculated.
3.) Air Cooled Split Units The Ceiling Cassette Split System has a knockout in the casing that allows outdoor fresh air to be introduced.
A fan may be added if the intake is far away.
Advantages •
•
•
•
•
Low first cost Flexibilities Easy to maintain Short lead time Ex Stock
Other Systems • • •
Low Efficiency No Fresh Air Potential IAQ issues
5. Water-cooled Splits/Packaged Units - WC Splits - Typ. Capacity range from 2.0 – 6 Hp - Ducted/Under ceiling
- WC Packaged - Typ. Capacity range from 20 – 100 Hp - Floor Standing Typical kw / ton around 1.0- 1.2 kw/ton
6. Variable Refrigerant System
On a single refrigerant pipe, many indoor units can be connected.
Advantages •
•
•
•
Flexibilities Better RH than ACSUs Space Saving Better EE than ACSUs
Others Systems •
•
Moderate Energy Efficiency Compared to CHWS Potential IAQ Problem
Chilled Water System control valve 80
F
(26.7
C)
°
54
F
°
(12.2
C)
50
F 110
F
C)(43.3
C)
°
(10
°
97
F
°
(36.1
C)
condenser
55
F
(12.8
C)
°
44
F
41
C)
(5.0
°
(6.7
F 100
F
C)(37.8
C)
°
°
87 (30.6
F C)
cooling tower
pump Airside Loop (AHU & Air Duct)
Chilled Water Loop (CHWP, Piping & Cooling Coil)
Refrigeration Loop (Water-cooled Chiller)
Condenser Water Loop (CWP, Piping & Cooling Tower)
Packaged Air-Cooled Chiller compressor
evaporator
Airside Loop (AHU & Air Duct)
Chilled Water Loop (CHWP, Piping & Cooling Coil)
expansion device Refrigeration Loop (Air-cooled Chiller)
air-cooled condenser
Conventional chilled water system
44
F
°
[6.7 54
F
[12.2
C]
°
3-way valve
C]
Primary-Secondary Configuration
primary pumps Variable secondary pump
production loop distribution loop two-way valve
Variable-Primary-Flow Systems Variable-flow pumps
check valves control valve
two-way valve optional bypass with three-way valve
Constant Primary Flow / Variable Secondary Flow Chilled Water System Secondary Pumps (Variable Speed)
Isolation Valves
Chiller
Chiller
(Constant Flow)
(Constant Flow)
s s a p y B g n i l p u o c e D
Load
Load
(Variable Flow)
(Variable Flow)
DP
Control Valves
Primary Pumps (Constant Speed) 13
Type of Chiller Compressors (Hermetic or Semi-Hermetic) Scroll Reciprocating
Helical-Rotary Screw
Centrifugal Compressor
Air-cooled Chiller •
20 – 100RT for Scroll
•
70 – 500 RT for Screw
Typical Efficiency range 1.1 – 1.3 kw/ton •
•
Applications : Retail, Commercial, Industrial & Government •
Scroll & Screw & some using Reciprocating
Water-cooled Chiller •
20 – 100RT for Scroll
•
70 – 400RT for Screw
100 – 2500 RT
•
Typical Efficiency range 0.5 – 0.7 kw/ton •
•
Applications : Retail, Commercial, Industrial & Govt. Buildings •
Scroll & Screw & some using Reciprocating
• Avoid VSD Chillers - Centrifugal Malaysian tropical climate has a near constant wet bulb temp thus VSDs do not save a huge amount of energy. In temperate climates, the WB drops significantly, thus the condenser water supply will also drop- at low CWS, the chiller compressors will overspeed During low wetbulb temperature the lift changes, thus causing the compressor to overspeed, which is similar to a car moving downhill. The new “lift” for the refrigerant is achieved by reducing the compressor speed- thus, the refrigerant will work more effectively during those periods of low wet bulb temperature. Source: Malaysian Industrial Energy Audit Guidelines – MIEEIP, PTM
Variable Speed Chillers – Screw or Centrifugal Good variable Part Load Value for 4-season areas. Low Ambient Need to carefully Evaluate Benefits.
Chiller Standard Performance Rating Standard ( Air-Conditioning, Heating and Refrigeration Institute)
AHRI STD. 551/591 – 2011
MS 1525:2007
Code of Practice on Energy Efficiency and Use of Renewable Energy for NonResidential Buildings (1st Revision)
Chillers Standard Rating Conditions 1.) MS 1525:2007 Code of Practice on Energy Efficiency and Use of Renewable Energy for Non-Residential Buildings (1 st Revision) Pg. 36 Section 8.11.1 Kw/Ton at 1.) 100% or Full load 2.) Part Load
Chiller Standard Performance Rating Standard Eurovent JIS GB MS2449:2012
MS 2449:2012
Performance rating of waterchilling packages using the vapor compression cycle
Included in AHRI STD Certification Program for 50 Hz Electrical Power
1.) Centrifugal & Screw Chillers with Continous Loading 2.) Rated 200 – 1,000 tons (703 – 3,517 KW ) at Standard ARI Rating Conditions. 3.) Hermetic & Open type, electric motor driven. 4.) Voltages up to 5,000 Volts.
Excluded in AHRI STD Certification Program for 50 Hz Electrical Power 1.) Scroll & Reciprocating compressor chillers with step unloading. 2.) Condenserless Chillers. 3.)Evaporatively Cooled Chillers. 4.) Chillers below 200 tons and above 1000 tons. 5.) Chillers with Voltages above 5000 volts. 6.) Chillers powered by other than electric motor drives. 7.) Chillers with motors not supplied with the unit by the manufacturer. 8.) Air-Cooled Chillers.
6.1 ) Percent Load
Weighting of Part Load Points
1992 Std
1998 Std
2003 Std
100%
17%
1%
1%
75%
39%
42%
42%
50%
33%
45%
45%
25%
11%
12%
12%
6.2) Fouling factors (h.ft² 1992
F/Btu) or (m². 1998
Cooler
0.00025
0.0001
Condenser
0.00025
0.00025
c/w)
A = kw/ton at 100% 100% Load C = kw/ton kw/ton at 50% Load B = kw/ton at 75% Load D = kw/ton at 25% Load Load
WHAT TEMP. TO USE FOR PART LOAD PERFORMANCE FROM 100% DOWN TO 0%
7.) Entering Condenser Water Temp. commonly used in Malaysia to evaluate Part Load Performance: Percent Load (1) (2) F F F 100% 85 87 87 75% 75 87 85.25 50% 65 87 83.5 25% 65 87 81.75 0% 65 87 80
Flow Rates and Temperatures 95
F
[35
C]
44
°
97
F
44
C] [36.1
C]
[6.7
F
°
[6.7
°
°
°
°
85
F
87
F
29.4
C]
[30.6
C]
°
F
°
°
°
°
°
F
54
F
C]
[12.2
C]
54
ARI conditions
°
[12.2
°
evaporator flow rate condenser flow rate
2.4 gpm/ton [0.043 L/s/kW] 3.0 gpm/ton [0.054 L/s/kW]
°
°
Malaysia Conditions
evaporator flow rate condenser flow rate
2.4 gpm/ton [0.043 L/s/kW] 3.0 gpm/ton [0.054 L/s/kW]
Typical Schematic of Chilled Water HVAC System Condenser water makeup
COOLING TOWERS
F
CHILLED WATER F
F
T
FCU T
F
15ºC AHU
T
T
AHU
RETURN F
15ºC R E C S º I 6 R D N I E A E M F
AHU
AIR FAN
F
T
F
T
C º 2 1 R E 9 S I N R R U N I T A E M R
15ºC
By Air T
By Refrigerant
F
PRIMARY CHILLED
T
WATER PUMPS CONDENSER WATER 35ºC
F
T
CONDENSER R O T A R O P A V E
15ºC SECONDARY CHILLED WATER PUMPS
By Air
F
F
1 R E L L I H C
2 R E L L I H C
F
3 R E L L I H C
F
R E S N E D N O C
WATER PUMPS
RETURN CONDENSER WATER 30ºC
By Water
The importance of controlling the flow of air and water in HVAC systems
Chillers – Flow R ates and Temperatures Why use 10 F 12 F 14 F •
•
•
10 F and how much above can we go ? = 2.4 USgpm/RT = 2.0 USgpm/RT = 1.7 USgpm/RT
Δ Saves Energy Equipment Rating Stds shouldn’t restrict us from designing more efficient CHW 1-1
Chiller Part Load Performance IPLV / NPLV
=____________1____________ 0.01 + 0.42 + 0.45 + 0.12 A
B
C
D
Where : A = KW/Ton at 100% , B = KW/Ton at 75 % C = KW/Ton at 50 % , D = KW/Ton at 25 % 25% Load 12%
45%
100% Load 1%
50% Load 75% Load
42%
1-2
Full Load Vs Part Load •
•
Both FullPart and Part Load Efficiency can be important. Full Load- Design Based On Consultant Calculation. (With or Without diversity factor) –
Part Load- May be running most of the time?
The arts and sciences of HVAC based on experience
Type of Refrigerants CFC
HCFC
HFC
R-11
•
R-22
•
R-134a
R-12
•
R-123
•
R404A
R-13
•
R-401A
•
R-407C
R-500
•
R-401B
•
R-410A
R-502
•
R-402A
•
R-507
R-503
•
R-402B
•
R-408A
•
R-409A
• • • • • •
HFO HFO 1234fy
5.) Refrigerant IssueEnvironmental Impact
•
•
•
ODP: Ozone Depletion Potential GWP: Global Warming Potential Climate Change
DX versus Chilled Water
Major factors Affecting the Decision •
Installed Cost
•
Energy Consumption
•
Type of Application
•
Space Requirements
•
Building Aesthetics
•
System Capacity
•
Centralized Maintenance
•
Stability of Control
•
Redundancy
Air-Cooled vs Water-Cooled
Air-cooled
Water-cooled
Typical Energy Usage in a Commercial Building in Hot/Humid climates
DHW 12%
Lighting 10%
Other Equipment 15%
Variable Frequency Drive (VFD)/ Variable Speed Drive (VSD)/ Speed Controller -Improve comfort levels -Reduce operating costs,
Approx. 60% - Air Conditioning Plant AHU/FCU 24%
Central Plant 39%
Chilled Water System: Direct or Reverse Return
DBCV - DYNAMIC BALANCING CONTROL VALVE PICV
PRES. INDEPENDENT CONTROL
–
VALVE
Design Pressure Independent Control Automatic balancing Commissioning
•
• •
Save installation space & time Save commissioning time & balancing Eliminate error
Illuminated enclosure
GREEN: normal RED: fault
Air Distribution System Methods of Air Flow Control
Air flow : Outlet dampers Inlet guide vanes Variable pitch fan Variable Speed Drive(VSD/VFD) • • • •
Water Distribution System
Methods of Water Flow Control Water Flow Centrifugal pumps : Bypass valve (three way) Throttling valve (two way) Trim Impeller (irreversible) Variable Speed Drive (VSD) • • • •
Fans and Centrifugal Pumps Fundamentals Affinity Laws Air Flow2 Fan Speed2 = Air Flow1 Fan Speed1 – Air/Water flow is proportional to Fan/Pump Speed
Static Pressure2 Static Pressure1
=
Air Flow2 Air Flow1
2
– Static Pressure is proportional to (Fan/Pump Speed)2
Input Power 2 Input Power 1
e.g
=
Air Flow2 Air Flow1
– Input Power is proportional to (Fan/Pump w/o system effect
3
80% speed Input power = (0.8x0.8x0.8)
Speed) 3
= 0.51 or 51%
Air Distribution System – Supply Fan Basics There are two types of air distribution systems i.)CAV - Constant Air Volume ii.)VAV – Variable Air Volume •
CAV Constant Air Volume –
•
•
In CAV systems, thermal comfort is achieved by delivering a constant volume of supply air. If location being served requires less cooling, the supply air temperature remain the same but the total volume of supply air remains the same as if full cooling is required
Air Distribution System
VFD/VSD Application - Supply Fan Basics •
There are two types of air distribution systems Variable Air Volume Constant Air Volume –
–
•
VFDs/VSDs are not only applied to VAV systems but can also be incorporated into CAV systems.
Supply Fan
Air Distribution System
CAV Supply Fan Basics •
Conditioned Space
No method of controlling air flow is provided
•
The conditioned space receives “Design” air flow at all times
•
The chilled water valves are
T Supply Fan
controlled by space temperature
•
However, for large single zone CAV systems, it’s possible to convert them to single zone VAV systems
Sensor may be in return air duct.
VAV Variable Air Volume –
•
•
To maintain thermally comfortable conditions, VAV systems utilize a resetable constant temperature of the delivered air to most locations, while varying the quantity of air delivered to the individual zones in the building. Varying the air flow is controlled by using a VFD/VSD in the fan motor.
VAV - Variable Air Volume System Components: 1. VAV Box 2. Zone Thermostat 3. Air Diffuser 4. Return Grille 5. Duct Static Pressure Sensor 6. Supply Fan VFD 7. AHU 8. Supply Duct
Zone 1
Zone 2
Zone 3
Zone 4
Air Distribution System
Why put a VFD/VSD on CAV SYSTEM •
Oversized systems
Variable Occupancy Profile E.g : Hotel Lobby, Office or Lift Lobby, Cineplex, Large Single Zone office, conference hall, etc..
•
Eliminate over capacity => energy saving, => Lower Acoustic Noise => easier balancing Better temperature control maintain minimum airflow - Vary from 70-100%
Air Distribution System CAV to — Single Zone VAV using VFD/VSD •
•
•
VFD controls air flow just as VAV boxes would Coils control supply air temperature
T Supply Fan
Works for large, single-zone systems
Maintain minimum airflow typically 70% and vary between 70-100% based on temp, Air quality or CO2 inputs
3 Input Power2 Air Flow2 = Input Power1 Air Flow1 Input Power is proportional to (Fan Speed) w/o system effect –
Conditioned Space
Supply Fan Drive
T
Sensor may be in return air duct.
eg 80% Input Power = (0.8 x 0.8 x 0.8) = 0.51 or 51%
Building code requirements Extract from Third Schedule (By-law 41)
ASHRAE STD 62.1-2010 62.1-2010 Ventilation For Acceptable For Indoor Air Quality Ventilation is the key to Sustainable IAQ and ASHRAE Std 62.1 is the Leading Standard adopted by most Local Authorities and HVAC HVAC Engineers in the world.
Acceptable Indoor Air Quality is defined as air in which there are Acceptable no known known Contaminants Contaminants at harmful Concentrations as determined determined by Cognizant Authorities and with which a substantial majority ( 80% or more ) of the people exposed do not express dissatisfaction. 1.) Ventilation Rate Procedure ( VRP ) – is a prescriptive procedure with a table of minimum required outdoor airflow rates per occupant for a variety of nonnon -
residential occupancies. The airflow rate per square foot of building floor area is basedon the design occupancy density and the required flow rate per person, adjusted to reflect the air distribution system used.
ASHRAE Std 62.1-2007 – Ventilation For Acceptable Indoor Air Quality
1.) Ventilatio Ventilation n Rate Procedure ( VRP ) Vbz = Rp.Pz + Ra.Az Where Vbz = Design outdoor airflow required in in the breathing zone of the occupied space or spaces in a zone,i.e the breathing zone outdoor air flow Az = Zone Zone floor area: the net occupiable occupiable floor area of the zone m2 ( ft2) Pz = zone population: the largest number of people expected to occupy the zone during typical usage. Rp = outdoor airflow rate required per person as determined from Table 6-1 Ra = outdoor airflow rate required per unit area as determined from Table 6-1
ASHRAE Std 62.1-2010 – Ventilation For Acceptable Indoor Air Quality
1.)
Ventilation Rate Procedure ( VRP )
2.)
Indoor Air Quality Procedure ( IAQ )
- air filtration/purification to remove some or all of the contaminants of concern can be part of the system.
TABLE 6-1
MINIMUM VENTILATION RATES IN BREATHING ZONE
People Outdoor Occupancy
Air Rate
Area Outdoor Air Rate
Default Values Occupant Density
Combined Outdoor Air Rate
R p
Category
Ra
cfm/ person
L/s person
cfm/ft ²
L/s m²
Office Space
5
2.5
0.06
Reception areas
5
2.5
0.06
#1000 ft² or #100 m²
cfm/ person
L/s person
0.3
5
17
8.5
0.3
30
7
3.5
Office Buildings
TABLE 6-1
MINIMUM VENTILATION RATES IN BREATHING ZONE
Hotels, Motels, Resort, Dormitories Bedroom / living room
5
2.5
0.06
0.3
10
11
5.5
Barracks sleeping areas
5
2.5
0.06
0.3
20
8
4.0
Laundry rooms, central
5
2.5
0.12
0.6
10
17
8.5
Laundry rooms within
5
2.5
0.12
0.6
10
17
8.5
7.5
3.8
0.06
0.3
30
10
4.8
5
2.5
0.06
0.3
120
6
2.8
dwelling units Lobbies / pre-function Multipurpose assembly
MS1525-2007 Air Conditioning and Mechanical Ventilation (ACMV) System
a) b) c) d) e)
a)
Indoor Design Condition Recommended Design DB Temperature Minimum DB Temperature Recommended Design RH Recommended Air Movement Maximum Air Movement
23 - 26ºC (73.4 – 78.8 22ºC 55% - 70% 0.15 m/s – 0.50m/s 0.7 m/s
Outdoor Design Conditions Recommended Outdoor Design Conditions DB / WB
33.3ºC / 27.2ºC ( 92 F/ 81 F ) °
°
F)
°
ASHRAE Comfort Zone
MS 1525:2007
Code of Practice on Energy Efficiency and Use of Renewable Energy for NonResidential Buildings (1st Revision)
8. Air-conditioning and mechanical ventilation (ACMV) system 8.1
Load calculations
8.2
System and equipment sizing
8.3
Separate air distribution systems
8.4
Controls
8.5
Piping insulation
8.6
Air handling duct system insulation
8.7
Duct construction
8.8
Balancing
8. Air-conditioning and mechanical ventilation (ACMV) system 8.9 8.10 8.11 8.12
ACMV systems ACMV system equipment ACMV system components ACMV system equipment/component
– heat operated (absorption), cooling mode 8.13 System testing and commissioning 8.14 Operation and maintenance (O&M) manual and as-built drawings 8.15 Preventive maintenance
8.1 Load calculations
8.1.1 Calculation procedures
Cooling system design loads for the purpose of sizing systems and equipment should be determined in accordance with the procedures described in the latest edition of the ASHRAE Handbook , or other equivalent publications.
8.1.2 Indoor design conditions
Room comfort condition is dependent on various factors including air temperature, mean radiant temperature, humidity, clothing, metabolic rate and air movement preference of the occupant. For the purpose of engineering design, room comfort condition should consider the following three (3) main factors: dry bulb temperature; relative humidity; and air movement (air velocity) •
•
•
8.1.4 Ventilation Outdoor air-ventilation rates should comply with Third Schedule (By Law 41) Article 12(1) of Uniform Building By Laws, 1984. Exception:
Outdoor air quantities may exceed those shown, if required because of special occupancy or process requirements or source control of air contamination or Indoor Air Quality consideration.
8.2 System and equipment sizing 8.2.1 Air conditioning systems and equipment shall be sized to provide no more than the space and system loads calculated in accordance with 8.1 above, consistent with available equipment capacity. Redundancy in capacity of equipment, if incorporated into the sizing of the duty equipment, should include efficiency devices such as variable speed drive, high efficiency motor, efficient unloading devices , multi compressors etc so as not to diminish the equipment/system efficiency when operating at varying loads.
8.2.2 Where chillers are used and when the design load is greater than 1,000 kWr, a minimum of either
two chillers or a single multi-compressor chiller should be provided to meet the required load. 8.2.3 Multiple units of the same equipment type, such as multiple chillers, with combined capacities exceeding the design load may be specified to operate concurrently only if controls are provided which sequence or otherwise optimally control the operation of each unit based on the required cooling load.
8.4 Controls 8.4.1 Temperature control
Each system should be provided with at least one thermostat for the regulation of temperature. Each thermostat should be capable of being set by adjustment or selection of sensors over a minimum range of between 22 C to 27 C. Multi-stage thermostat should be provided for equipment exceeding 35/65 kWr in conjunction with 8.2.4.
8.4.2 Humidity control
In a system requiring moisture removal to maintain specific selected relative humidity in spaces or zones, no new source of energy (such as electric reheat) should be used to produce a space relative humidity below 70 % for comfort cooling purposes.
8.4.3 Energy Recovery
It is recommended that consideration be given to the use of recovery systems which will conserve energy (provided the amount expended is less than the amount recovered) when the energy transfer potential and the operating hours are considered. Recovered energy in excess of the new source of energy expended in the recovery process may be used for control of temperature and humidity. Examples include the use of condenser water for reheat, desuperheater heat reclaim, heat recovery wheel, heat pipe or any other energy recovery technology.
8.4.5 Mechanical ventilation control
Each mechanical ventilation system (supply and/or exhaust) should be equipped with a readily accessible switch or other means for shut-off or volume reduction when ventilation is not required. Examples of such devices would include timer switch control, thermostat control, duty cycle programming and CO/CO2 sensor control.
8.4.6 Fan System Efficiency
For fan system with air flowrate exceeding 17000 m3/h and operating for more than 750 hours a year, the power required by the motor for the entire fan system at design conditions should not exceed 0.45 W per m3/h of air flowrate.
8.7
Duct construction
All ductwork should be constructed and erected in accordance with HVAC Duct Construction Standards Metal and Flexible published by SMACNA or any other equivalent duct construction standards. High-pressure and medium-pressure ducts should be leak tested in accordance with HVAC Air Duct Leakage Test Manual published by SMACNA or any other equivalent standards, with the rate of leakage not to exceed the maximum rate specified.
8.7.1
8.8
Balancing
The system design should provide means for balancing the air and water system such as but not limited to dampers, temperature and pressure test connections and balancing valves.
8.10 ACMV system equipment •
•
ACMV system equipment provides, in one (single package) or more (split system) factory assembled packages, means for air-circulation, air-cleaning, aircooling with controlled temperature and dehumidification. The cooling function may be either electrically or heat operated , and the refrigerant condenser may be air, water or evaporativelycooled. Where the equipment is provided in more than one package, the separate packages should be designed by the manufacturer to be used together.
8.13 System testing & commissioning •
•
•
Air system balancing should be accomplished in a manner to minimise throttling losses and then fan speed shall be adjusted to meet design flow conditions. Hydraulic system balancing should be accomplished in a manner to minimise throttling losses and then the pump impeller impeller should be trimmed trimmed or pump speed should be adjusted to meet design flow conditions. ACMV control systems should be tested to assure that control elements are calibrated, adjusted and in proper working condition.
8.15 Preventive Maintenance
•
The owner should implement preventive maintenance system and schedule periodic maintenance on all the critical items of air-conditioning systems such as compressors, cooling towers, pumps, condensers, air handlers, controls, filters and piping.
AHU Room with Acoustical Problems
What is Legionnaires’ Disease? - Respiratory disease - Bacteria – Legionella pneumophilia - Found in any aquatic environment e.g; Cooling towers, evaporative condensers, showers, whirlpool spas, humidifies, decorative fountains, fire sprinklers systems.
Sign and Symptoms of Legionnaires’ Disease - Usually begins with a headache, pain in the muscles and a general feeling un-wellness. - High fever (up to 40 -40.5 deg C or about 104-105 deg.F) and shaking chills. °
- Nausea, vomiting and diarrhea may occur - Dry coughing and chest pain might occur - 5 -15% of known cases have been fatal
Who is more likely to get Legionnaires’ disease? - Middle aged or older people - Those who smoke tobacco or have chronic lung disease - Low resistance to infection / immune system
Workers most at risk - Those who maintain cooling towers in air conditioning systems
How to Prevent Legionnaires’ Disease? a)
Good engineering practices in the operation and maintenance of the system.
-
Cooling towers should be inspected and thoroughly cleaned at least once a year.
b) Corroded parts, such as drift eliminators should be replaced. c)
Algae and accumulated scale should be removed.
d)
Cooling towers water should be treated constantly.
Location of Cooling Towers - Locate away from fresh air intakes. - Locate away from kitchen exhaust fans, plants, truck bays, or other sources of organic matter - Consider direction of prevailing wings. - Consider future construction.
Industry Code of Practice on Indoor Air Quality 2010 DOSH Malaysia* Ministry of Human Resources Table 1: List of Indoor Air Contaminants and the Maximum Limits
Acceptable Range for Specific Physical Parameters – Proposed 2010 Parameter (a) A ir temperature (b)
R elative humidity
(c)
A ir movement
A cceptable rang e 23.0 – 26.0 ºC 40 – 70% 0.15 – 0.50
List of Indoor Air Contaminants and acceptable limits
Indoor A ir C ontaminants
Chemical contaminants (a) Carbon dioxide (b) C arbon monoxide (c) Formaldehyde (d) Ozone (e) R espirable particulates (f) Total volatile org anic compounds (TVOC) Biological contaminants (a) Total bacterial counts (b) Total fung al counts
E ig ht-hours time-weig hted averag e airborne concentration ppm
mg/m³
cfu/m³
C1000 10 0.1 0.05 3
0.15 -
-
-
-
500 1000
Carbon Dioxide and DCV •
CO2-based DCV has the most energy savings potential in buildings where occupancy fluctuates. –
Office buildings, government facilities, retail stores and shopping malls, airports, theaters, auditoriums, conference or lecture halls, entertainment areas are good candidates for DCV
Carbon Dioxide and DCV •
Benefits –
–
Improved IAQ Increasing ventilation if CO 2 levels rise to unacceptable levels. Improved humidity control In humid climates, DCV can prevent unnecessary influxes of humid outdoor air that makes occupants uncomfortable and encourages mould & mildew growth –
–
Typical Installation – AHU Room Return Air
AHU Room
CO2 sensor
Supply Air
AHU Fresh Air Fresh air damper
Damper Actuator
Energy Monitoring Energy meter EFC3500 DA NF OS S
Air Handling Unit Pt 500 RTD
Flowmeter
Pt 500 RTD
The operation principle of inline magnetic flowmeters
Full Bore Flange Type
Type of Flow Meters
•
Electronic Flow Meters – Full Bore Flange Type
Electromagnetic Qualities
Obstruction free
No moving parts
Wide flow range
Virtually no maintenance
Minimal installation requirements
Typical accuracy at 0.25% and 0.5%
Full BMS Integration
Measures the velocities across the pipe line cross section
Insensitivity to viscosity, specific gravity, temperature and pressure
Respond well to fast changing flows
Lower life-cycle costs
When an electrical conductor moved at velocity, perpendicular to the lines of flux through a magnetic field of strength, the voltage is induced at the ends of the conductor
Type of Flow Meters Electronic Flow Meters Ultrasonic Obstruction free No moving parts Wide flow range Virtually no maintenance Sensitive to pipe elbows and control valves Respond well to fast changing flows Full BMS Integration Low Cost of Ownership on larger pipe (>DN300)
Measuring Principle Acoustic flow measuring procedures like the ultrasonic-flow measurement use sound waves above the hearing barrier, i.e.> 20 kHz for speed and flow measurement. The velocity and direction of the sound rays change due to the transport of the sound waves in the fluid. With the transit time procedure, the time is measured in which a sound wave takes to get around path 1. I.e. point A, the
What is a “Green Design” or Sustainable Design? • ASHRAE GreenGuide provides one definition for sustainable building design:
“Sustainability is the providing of the needs of the present without detracting from the ability to fulfill the needs of the future”
What’s Green Building? • USEPA- practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building’s lifecycle from design , construction,operation , maintenance, renovation and even deconstruction. • - Sustainable or High-Performance building • Source: IEM Jurutera June 2010 Bulletin
Green Building Rating System
Canada LEED Canada BREEAM Canada Green Globe
UK BREEAM Italy Protocollo ITACA
USA LEED Energy Star Green Globe Brazil GBTool
Korea GBTool
China Japan 绿色建筑评估标准 CASBEE Hong Kong India HK-BEAM LEED-India Malaysia Taiwan 綠建築標章 GBI Singapore Green Mark Australia Green Star
Australia: Nabers / Green Star Brazil: AQUA / LEED Brasil Canada: LEED Canada / Green Globes China: GBAS Finland: PromisE France: HQE Germany: DGNB / CEPHEUS Hong Kong: HKBEAM India: GRIHA Italy: Protocollo Itaca / Green Building Counsil Italia Malaysia: GBI Malaysia Mexico: LEED Mexico Netherlands: BREEAM Netherlands New Zealand: Green Star NZ Philippines: BERDE / Philippine Green Building Council Portugal: Lider A Singapore: Green Mark South Africa: Green Star SA Spain: VERDE Switzerland: Minergie United States: LEED / Living Building Challenge / Green Globes / Build it Green / NAHB NGBS United Kingdom: BREEAM United Arab Emirates: Estidama • • • • • • • • • • • • • • • • • • • • •
• •
GLOBAL GREEN TOOLS 1. 2. 3. 4. 5. 6. 7. 8. 9.
BREEAM, UK – Building Research Establishment Environmental Assessment Method (1990) LEED, USA – Leadership in Energy and Environmental Design (1996) BEAM, Hong Kong – Building Environment Assessment Method (2003) EEWH, Taiwan – Green Building Evaluation System (2003) Green Star, Australia/New Zealand (2003) CASBEE, Japan – Comprehensive Assessment System for Building Environmental Efficiency (2004) Green Mark, Singapore (2005) Green Building Index, Malaysia (2009) Greenship, Indonesia (2010)
Building Energy Intensity
BEI = (TBEC - CPEC - DCEC)*(52/WOH) (GFAex.cp - DCA - GLA*FVR) where: “ex.cp” denotes excluding car park
BEI =
(TBEC - CPEC - DCEC)*(52/WOH) (GFAexcl carpark - DCA - GLA*FVR)
Where; TBEC: Total Building Energy Consumption (kWh/year) for all landlord and tenancy areas. CPEC: Carpark Energy Consumption (kWh/year) for carpark area (which is not air-conditioned) and typically covers artificial lighting, lifts, mechanical ventilation fans, sump pumps and plug loads (car washing facilities). Installations serving the whole building (such as hydraulic pumps and fire pumps) shall not be included. DCEC: Data Centre Energy Consumption (kWh/year) for operation of the Data Centre equipment and for controlling its indoor environment (air-conditioning, mechanical ventilation, lighting and plug loads). GFAexcluding carpark : Gross Floor Area of buildings exclusive of car park area (m2)
BEI =
(TBEC - CPEC - DCEC)*(52/WOH) (GFAexcl carpark - DCA - GLA*FVR)
DCA: Gross area of Data Centre (m2) GLA: Gross Lettable Area (m2) refers to the total functional use area for commercial purposes such as office, retail, cafeteria, restaurant, gymnasium and club house inside the building but excluding all common areas and service areas. The sum of GLA, common areas and service areas should equal the GFA excluding car park. FVR: Floor Vacancy Rate is the weighted floor vacancy rate of office, retail and other functional spaces of GLA. The FVR (%) of GLA is equal to the non-occupied lettable area divided by the GLA. 52: Typical weekly operating hours of office buildings in KL/Malaysia (hrs/wk) = 2,700 hrs/annum WOH: Weighted Weekly Operating Hours of GLA exclusive of DCA (hrs/wk)
BEI EE5 pts Office Retail Hotel
Hospital
Etc
2
150
240
200
200
?
3
140
225
190
190
?
5
130
210
175
175
?
8
120
195
160
160
?
10
110
180
150
150
?
12
100
160
135
135
?
15
90
145
120
120
?
Electrical Sub-Metering •
Separate metering provided for the following; –
Landlord and/or tenant
–
Lift and escalator
–
Major water pumping system
–
Central air-conditioning system
–
Car park and common area lighting/power system
–
External and façade lighting
Separate electricity metering to be linked to EMS
