Hvac Design Thumb Rules

HVAC DESIGN THUMB RULES Anuj Bhatia AIR-CONDITIONING CAPACITY 1) A ton of refrigeration (1TR) signifies the ability of airconditioning equipment to extract heat @ 12000 Btu/hr. ASHARE (American Society of Heating, Refrigeration and Airconditioning Engineers, Inc) has put together a table using national average data showing the Sq-ft/Ton as follows: Sq-ft/Ton

High

Average

Low

Residential

600

500

380

Office

360

280

190

3) Each building is different and the design conditions differ greatly between regions to region. Factors to consider when figuring the sq-ft/ ton ratio include:  Climate conditions (design temperatures)  Expansive use of glass-particularly in the south and west orientations  High ceilings-increasing the conditioned volume of the space  Outside air requirements-especially important in high occupant load areas like conference rooms and classrooms.

 Heat generating equipment – example computers, copiers, laser printers, big screen TV’s etc.  Lighting-especially the extensive use of incandescent and metal halide lights. Fluorescent lights are more efficient and burn cooler-however; their ballasts generate a fair amount of heat. Application

Average Load

Residence

400-600 sq. ft. floor area per

Apartment (1 or 2 room)

ton

Church

400 sq. ft. of floor area per ton 20 people per ton

Office Building Large Interior

340 sq. ft. of floor area per

Large Exterior

ton

Small Suite

250 sq. ft. of floor area per ton 280 sq. ft. of floor area per ton

Restaurant


Bar or Tavern

ton

Cocktail Lounge

9 people per ton 175 sq. ft. of floor area per

Application

Average Load ton

Computer Room

50 – 150 sq. ft. of floor area

Bank (main area)

per ton

Barber Shop

225 sq. ft. of floor area per ton 250 sq. ft. of floor area per ton

Beauty Shop


School Classroom

ton

Bowling Alley

250 sq. ft. of floor area per ton 1.5 – 2.5 tons per alley

Department Store Basement


Main Floor

ton

Upper Floor


Small Shop

ton 400 sq. ft. of floor area per ton 225sq. ft. of floor area per ton

Dress Shop


Application

Average Load

Drug Store

ton

Factory (precision


manufacturing)

ton 275 sq. ft. of floor area per ton

Groceries – Supermarket


Hospital Room

ton

Hotel Public Spaces

280 sq. ft. of floor area per ton 220sq. ft. of floor area per ton

Motel


Auditorium or Theatre

ton 20 people per ton

Shoe Store


Specialty & Variety Store

ton 200 sq. ft. of floor area per ton

Air-conditioning requirements are higher (200 to 400 sq-ft/Ton) for hot and humid regions and lower (150 – 200 sq-ft/Ton) for cooler places.

Note: The figures above indicative only. It is recommended to always generate a detailed heating and cooling load calculation (such as using Manual J) for the building or space in question.

AIR CONDITIONER CAPACITY RANGES The application and unit capacity ranges are as follows: 1. Room air conditioner - Capacity ranges 0.5 to 2 TR per unit, suitable for an area of not more than 1000 square feet 2. Packaged unit integral air-cooled condenser - Capacity ranges 3 to 50 TR, suitable for a maximum an area of 1000 – 10000 square feet 3. Split system with outdoor air-cooled condenser - Capacity ranges 0.5 to 50 TR, suitable for an area of 100 – 10000 square feet 4. Central air-conditioning chilled water system with air cooled condensers – Capacity ranges of 20 to 400 TR, suitable for an area of 4000 sq-ft and higher 5. Central air-conditioning chilled water systems with outdoor water cooled condenser - Capacity ranges 20 to 2000 TR, suitable for an area of 4000 sq-ft and higher.

COOLING CAPACITY SELECTER FOR HOMES

Air conditioners are sized by cooling capacity in BTU's per hour. To estimate the optimum capacity for any room, first calculate the size of the area to be conditioned by multiplying its width times its length, measured in feet. Then select the cooling capacity needed using the table below, The BTU's associated with the square footage will give an approximate optimum for the space.

Room Area

Square Feet

Cooling Capacity (BTU range)

10X15

150

up to 5200

10X20

200

6000

15X20

300

7500

17X20

340

8000

18X25

450

10000

22X25

550

12000

25X28

700

14000

25X32

800

15000

25X34

850

16000

25X40

1000

18000

27.5X40

1100

20000

35X40

1400

24000

37.5X40

1500

28000

40X40

1600

32000

Room Area

Square Feet

Cooling Capacity (BTU range)

Notes to using the table above Cooling capacities are based on rooms occupied by two people and having average insulation, number of windows, and sun exposure. To adapt the table for varying conditions, modify the capacity figures as follows: 1. Reduce capacity by 10% if area is heavily shaded. 2. Increase capacity by 10% for very sunny areas. 3. Add 600 Btu/hr for each additional person if area is occupied routinely by more than two people. 4. Add 4000 Btu/hr if area to be cooled is an average size kitchen. 5. Add 1000 Btu/hr for every 15 sq/ft of glass exposed to sun. 6. Add 3414 Btu/hr for every 1000 watts of electronic equipment.

SUPPLY AIR REQUIREMENTS (MECHANICAL COOLING & HEATING)

Equipment Type

Approximate

Example

Airflow Rate Gas/Oil Furnace

1 CFM per 100

64000 Btu/hr

Btu/hr output

output furnace = 640CFM

Electric Furnace

50 – 70 CFM per

10kW furnace =

kW input

10 x 70 = 700CFM 30kW furnace = 30 x 50 = 1500CFM

Electric Air-

400 CFM per ton

conditioning

30000 Btu/hr cooling 30000/12000= 2.5tons 2.5 x 400 = 1000 CFM

Heat Pump

450 CFM per ton

30000 Btu/hr cooling 30000/12000= 2.5tons 2.5 x 450 = 1125 CFM

Note the values vary significantly with the equipment. CFM/kW tends to be higher with smallest equipment (5-15kW) and lower as equipment becomes larger. In general, the following guidelines may be noted: 

500 CFM/ton for Precision Air Conditioning



400 CFM/ton for Comfort Cooling Air Conditioning



200 CFM/ton Dehumidification

SELECTION OF CHILLERS The following is used as a guide for determining the types of liquid chillers generally used for air conditioning  Up to 25 tons (88kW) – Reciprocating  25 to 80 tons (88 to 280kW) – Reciprocating or Screw  80 to 200 tons (280 to 700kW) – Reciprocating, Screw or Centrifugal  200 to 800 tons (700 to 2800kW) – Screw or Centrifugal  Above 800 tons (2800 kW) – Centrifugal Circumstances Favouring Air-Cooled or Water Cooled Systems Capacity Range (TR)

Favourable System

40 to 200

Air-cooled chilled water

system (explore the pros and cons of using multiple DX systems if possible) 200 and above

Water-cooled chilled water system

CHARACTERISTICS & TYPICAL APPLICATIONS OF VARIOUS COOLING SYSTEMS

Air-Cooled

Water-

Air-Cooled

Water-

Cooled

Chilled-

Cooled

Packaged Packaged

Water

Chilled-

Equipmen Equipmen

System

Water

Characteri stics

t

t

System

Typically Building Height

limited to 1- to 4-

Unlimited

Unlimited

Unlimited

story buildings

Minimum

No

Typically

Typically

Typically

Cooling

limitation

cost-

cost-

cost-

Capacity

for modular effective

effective

effective

Air-Cooled

Water-

Air-Cooled

Water-

Cooled

Chilled-

Cooled

Packaged Packaged

Water

Chilled-

Equipmen Equipmen

System

Water

Characteri stics

t

systems Cooling Control Maintenanc e Installed Cost

Low

Low

Low

Operating Costs (energy

System

for projects for projects for projects >20 tons Lowmoderate Moderatehigh Moderatehigh

>100 tons >200 tons High

High

Moderate

High

High

High

LowModerate

and water) Typical

t

moderate

Moderate-

(climate

high

Low

dependent) 1- to 2-

1- to 2-

Medium to Medium to

Application story

story

large

s

buildings in facilities

facilities

hot/dry

and

buildings

with

very large

Air-Cooled

Water-

Air-Cooled

Water-

Cooled

Chilled-

Cooled

Packaged Packaged

Water

Chilled-

Equipmen Equipmen

System

Water

Characteri stics

t

t

System

limited access to climates

water or

campuses

maintenan ce

CONVERTING KW/TON TO COP or EER If a chiller's efficiency is rated at 1 KW/ton, the COP=3.5 and the EER=12 kW/ton

12 / EER

kW/ton

12 /(COP x 3.412)

EER

12 / (kW/ton)

EER

COP x 3.412

COP

EER / 3.412

COP

12 / (kW/ton x 3.412)

TYPICAL EFFICIENCIES OF HVAC EQUIPMENT A gas furnace has 78% AFUE efficiency (heat out delivered / heat in fuel burned). An air conditioner or heat pump has 10 SEER or EER (Btu/hr/w). The heating part of a heat pump achieves 6.6 Btu/hr/w heating season HSPF. RECOMMENDED EFFICIENCY VALUES FOR UNITARY & APPLIED HEAT PUMPS

Equipment

Size

Sub-

Required

Type

Category

Category or

Efficiency

Rating Condition Split System

Air Cooled (Cooling

< 65,000 Btuh Single

Mode)

Package

13.0 SEER 13.0 SEER

> 65,000 Btuh Split System and

and

11.0 EER

< 135,000

Single

11.4 IPLV

Btuh

Package

> 135,000 Btuh and <240,000 Btuh

Split System and Single Package

10.8 EER 11.2 IPLV

Equipment

Size

Sub-

Required

Type

Category

Category or

Efficiency

Rating Condition > 240,000 Btuh

Split System and Single Package

Air Cooled

< 65,000 Btuh Split System

(Heating

(Cooling

Single

Mode)

Capacity)

Package

> 65,000 Btuh 47°F db/43°F wb and < 135,000

Outdoor Air

Btuh

17°F db/15°F

(Cooling

wb

Capacity)

Outdoor Air

10.0 EER 10.4 IPLV 8.0 HSPF 7.7 HSPF

3.4 COP

2.4 COP

47°F db/43°F >135,000

wb

Btuh

Outdoor Air

(Cooling

17°F db/15°F

Capacity)

wb

3.3 COP

2.2 COP

Outdoor Air Water Source

< 135,000

85°F Entering 14.0 EER

Equipment

Size

Sub-

Required

Type

Category

Category or

Efficiency

Rating Condition (Cooling Mode)

Water-Source (Heating Mode)

Btuh (Cooling

Water

Capacity) < 135,000 Btuh

70°F Entering

(Cooling

Water

4.6 COP

Capacity)

RECOMMENDED CHILLER PERFORMANCE LEVELS

ELECTRIC UTILIZATION INDEX (EUI) Electric utilization index (EUI) is the ratio of annual electricity consumption in kWh to the facility’s square footage. Type of Building

Common EUI

Grocery

61.0

Restaurant

38.9

Hospital / Health

16.4

Retail

12.1

School / College

10.3

Hotel / Motel

8.2

Office

7.5

Misc. Commercial

6.4

Warehouse

6.1

HEAT GAIN FROM OCCUPANTS AT VARIOUS ACTIVITIES (At Indoor Air Temperature of 78°F)

Activity

Total heat, Btu/h

Sensible

Latent

Adult,

heat,

heat,

Btu/h

Btu/h

Adjusted

male Seated at

400

350

210

140

480

420

230

190

520

580

255

325

640

510

255

255

800

640

315

325

rest Seated, very light work, writing Seated, eating Seated, light work, typing Standing, light work

or walking slowly Light

880

780

345

435

1040

1040

345

695

1360

1280

405

875

1600

1600

565

1035

2000

1800

635

1165

bench work Light machine work, walking 3miles/hr Moderate dancing Heavy work, lifting Athletics

The values are for 78°F room dry bulb temperature. For 80°F dry bulb temperature, the total heat remains the same, but the sensible heat value should be decreased by approximately 8% and the latent heat values increased accordingly. HEAT TRANSFER THROUGH BUILDING ASSEMBLY Typical Conductance U- Values in Btu / (hr square foot °F) More insulation gives lower conductance. Less insulation gives higher conductance.

These values include inside and outside air films, typical construction, and effect of framing members.  Heat conductance of building wall: Use 0.088 for R-13 insulated house wall.  Heat conductance of building floor: Use 0.047 for R-13 insulated house raised floor.  Heat conductance of building ceiling: Use 0.031 for R30 insulated ceiling including attic and roof.  Heat conductance of building roof: Use 0.031 for R30 insulated roof including attic and ceiling.  Heat conductance of window glass: Use 0.65 for dual pane window. Typical Resistance Values in (hr square foot °F) / Btu More insulation gives higher resistance. Less insulation gives lower resistance. These values include inside and outside air films, typical construction, and effect of framing members.  Heat resistance of building wall: Use 11.3 for R-13 insulated house wall.  Heat resistance of building floor: Use 21.4 for R-13 insulated house raised floor.  Heat resistance of building ceiling: Use 32.5 for R30 insulated ceiling including attic and roof.

 Heat resistance of building roof: Use 32.5 for R30 insulated roof including attic and ceiling.  Heat resistance of window glass: Use 1.54 for dual pane window. SOLAR LOADS Solar – winter The contribution of solar heat is ignored for the sizing of winter heating equipment. It is most likely the greatest need for winter heat will occur at a time when the sun is not out. Solar – summer Estimate 60 Btu/hr. / square foot enters every window on average during the daylight hours. (Although there are about 450 Btu/hr. per square foot of sunlight, this amount is not entering every window simultaneously, and there are many other reasons to calculate with the lower rate. For discussion, see solar through windows.) This estimate assumes even distribution of windows around all sides of the building, some overhangs, some window tinting, and curtains that are left open. For other or non-average window conditions, a better solar estimate may be necessary. VENTILATION RECOMMENDATIONS

Application

Occupancy

CFM/perso

(people/1000

n

ft2) Food and

Dining

70

20

Beverage

rooms

Service

Cafeteria,

100

20

100

30

20

15

Office space

7

20

Reception

60

15

50

20

70

60

Elevators

30

60

Retail

Basement &

20

25

stores,

Street 20

15

70

15

fast food Bars, cocktail lounges Kitchen (cooking) Offices

areas Conference rooms Public

Smoking

Spaces

lounge

Showrooms Upper floors Malls and arcades

Smoking

25

25

8

20

150

25

70

20

30

15

100

15

150

15

Lobbies

150

15

Auditorium

50

15

Classroom

50

15

Music rooms

20

20

Libraries

150

15

Auditoriums

30

30

Hotels,

Bedrooms

50

30

Motels

Living rooms

120

30

Lobbies

30

25

lounges Beauty shops Hardware stores Sports and

Spectator

Amusemen

areas

ts

Games rooms Playing rooms Ballrooms and discos

Theatres

Education

Resorts,

Dormitorie

Conference

120

20

s

rooms 20

15

10

15

30

15

20

20

20

20

Laboratories

20

30

Procedure

70

15

Pharmacies

100

20

Physical

100

15

Assembly rooms Dry cleaning, laundry Gambling casinos Health Care Operating Facilities

rooms Patient rooms

rooms

therapy

EXHAUST AIR REQUIREMENTS

Exhaust Air Requirements Janitor Closets

10 Air changes/hr

Locker Rooms

10 Air changes/hr

Toilets

10 Air changes/hr

Mechanical/Electrical Rooms

12 Air changes/hr

Rooms with Steam System

25 Air changes/hr

(Laundry) Battery Rooms

10 Air changes/hr

TYPICAL DESIGN VELOCITIES FOR HVAC COMPONENTS

Equipment

Velocity, Feet per minute (FPM)

Intake Louvers Velocity (7000

400 FPM

CFM and greater) Exhaust Louvers (5000 CFM and 500 FPM greater) Panel Filters Viscous Impingement

200 to 800 FPM

Panel Filters (Dry-Type, Pleated Media) Low Efficiency

350 FPM

Medium Efficiency

500 FPM

High Efficiency

500 FPM

HEPA

250 FPM

Renewable Media Filters Moving-Curtain Viscous

500 FPM

Impingement Moving-Curtain Dry-Media

200 FPM

Electronic Air Cleaners Ionizing-Plate-Type

300 to 500 FPM

Charged-Media Non-ionizing

250 FPM

Charged-Media Ionizing

150 to 350 FPM

Steam and Hot Water Coils

200 min - 1500 max

Electric Coils Open Wire

Refer to Mfg. Data

Finned Tubular Dehumidifying Coils

500 FPM

Spray-Type Air Washers

300 to 600 FPM

Cell-Type Air Washers

Refer to Mfg. Data

High-Velocity, Spray-Type Air

1200 to 1800 FPM

Washers

CENTRIFUGAL FAN PARAMETERS

Centrifugal fans are by far the most prevalent type of fan used in the HVAC industry today. They are usually cheaper than axial fans and simpler in construction, but generally do not achieve the same efficiency. Centrifugal fans consist of a rotating wheel, or "impeller," mounted eccentrically inside a round housing. The impeller is electrically driven by a motor connected via a belt drive. Paramet

Backward Curve

ers

Forward Curve

BC

BI

AF

FC

Blades

6-16

6-16

6-16

24-64

Maximum

78

85

90

70

Speed

High

High

High

Low

Cost

Medium

Medium

High

Med-Low

Static

Very high

High

Very high

Low (5

(40in-wg)

inch- w.g)

Non-

Overloadi

Efficiency (%)

Pressure Power

Non-

Curve

overloadin overloadin overloadin ng

Housing

Non-

g

g

g

Scroll

Scroll

Scroll

AXIAL FAN PARAMETERS

Scroll

Axial fans consist of a cylindrical housing, with the impeller mounted inside along the axis of the housing. In an axial fan, the impeller consists of blades mounted around a central hub similar to those of an airplane propeller. Typically, axial fans are more efficient than centrifugal fans. Parameters

Propellers

Tube Axial

Vane axial

Blades

2 to 8

4 to 8

5 to 20

Maximum

50

75

85

Speed

Medium

High

Very high

Cost

Low

Medium

High

Static

Low (up to ¾

Medium

High (up to 8

Pressure

in)

Power Curve

Non-

Non-

Non-

overloading

overloading

overloading

Annular ring

Cylindrical

Cylindrical

Efficiency (%)

Housing

in)

with guide vanes on downstream side

FAN PERFORMANCE RELATIONSHIPS

Variable

Constant

Law

Equation

Rotational

Fan Size

Flow is

(Q1 / Q2) =

Speed

Air Density

directly

(N1 / N2)

Duct System

proportional to speed Pressure is

(P1 / P2) =

directly

[(N1 / N2)]2

proportional to speed2 Power is

(HP1 / HP2) =

directly

[(N1 / N2)]3

proportional to speed3 Fan Size and

Tip Speed

Flow and

(Q1 / Q2) =

Rotational

Air Density

power is

(HP1 / HP2) =

directly

[(D1 / D2)]2

Speed

proportional to diameter2 Speed is

(N1 / N2) =

inversely

(D2 / D1)

proportional to diameter Pressure remains constant

P1 = P 2

Variable

Constant

Law

Equation

Fan Size

Rotational

Flow is

(Q1 / Q2) =

Speed

directly

[(D1 / D2)]2

Air Density

proportional to Diameter2 Flow is

(P1 / P2) =

directly

[(D1 / D2)]2

proportional to Diameter2 Power is

(HP1 / HP2) =

directly

[(D1 / D2)]3

proportional to Diameter3 Rotational

Fan Size

Speed, flow

(N1 / N2) =

Speed and Air Pressure

and power

(Q1 / Q2) =

Density

are inversely

(HP1 / HP2) =

proportional

[(ρ1 / ρ2)]1/2

to square root of density Air Density

Rotational

Pressure and

(P1 / P2) =

Speed

power are

(HP1 / HP2) =

Fan Size

directly

(ρ1 / ρ2) =

Duct System

proportional to density Flow remains

Q1 = Q2

Variable

Constant

Law

Equation

constant

GUIDE TO AIR OUTLET SELECTION Tables below provide a general guide for the proper selection of outlets based on design requirements of CFM per square foot and air changes per hour (SMACNA 1990). Floor Space Type of

Approximat

CFM per Sq

Lps per Sq-

e maximum

Feet

m

air

Outlet

changes/ho ur for 10 feet ceiling

Grilles &

0.6 to 1.2

3 to 6

7

Slot Diffusers

0.8 to 2.0

4 to 10

12

Perforated

0.9 to 3.0

5 to 15

18

0.9 to 5.0

5 to 25

30

1.0 to 10.0

5 to 50

60

Registers

Panel Ceiling Diffuser Perforated Ceiling

REFRIGERANTS & ENVIRONMENTAL FACTORS In general the comparison of 4 most common refrigerants employed today on environmental factors is as below: Criteria

HCFC-

HCFC-22

123 Ozone

HFC-

Ammonia

134a

0.016

0.05

0

0

85

1500

1200

0

2030

2020

N/A

N/A

Low

Low

Low

Low

No

No

No

Yes

Depletion Potential Global Warming Potential (relative to CO2) Phase out Date Occupatio n Risk Flammabl e

CURRENT & FUTURE REFRIGERANTS

Equipment Type

Traditional

Replacement

Refrigerant

Refrigerants

HCFC-22

R407C, HFC-134a

Scroll Chiller

HCFC-22

R407C, R-410A

Reciprocating

HCFC-22

R-407C, R-410A

Absorption Chiller

R-718 (water)

R-718

Centrifugal Chiller

CFC-11, CFC-12

HFC-134a, HCFC-

Rotary Screw Chiller

Chiller

123 Packaged Air

HCFC-22

R-407C, R-410A

Heat Pump

HCFC-22

R-407C, R-410A

PTAC, PTHP

HCFC-22

R-407C, R-410A

Room Air

HCFC-22

R-407C, R-410A

Conditioners

conditioning

RECOMMENDED SHEET METAL THICKNESS FOR DUCTS

Rectangular Duct

Round Duct

Greate

Galvani

Alumin

Diamet

Galvani

Alumin

st

zed

um

er

zed

um

Steel

(gauge

Dimens Steel

(gauge

ion

(gauge) )

Up to 30 24

22

inch 31 – 60

22

20

s and

24

22

9 – 24

22

20

20

18

18

16

inches 20

18

inches 91inche

Up to 8 inch

inches 61 – 90

(gauge) )

25 – 48 inches

18

16

49 – 72 inches

above

SHEET METAL THICKNESS & WEIGHTS

Gauge (or gage) sizes are numbers that indicate the thickness of a piece of sheet metal, with a higher number referring to a thinner sheet. The equivalent thicknesses differ for each gauge size standard, which were developed based on the weight of the sheet for a given material. The Manufacturers' Standard Gage provides the thicknesses for standard steel, galvanized steel, and stainless steel. The Brown and Sharpe Gage, also known as the American Wire Gage (AWG), is used for most non-ferrous metals, such as Aluminium and Brass. The chart below can be used to determine the equivalent sheet thickness, in inches or millimetres, for a gauge number

from the selected gauge size standard. The weight per unit area of the sheet can also be seen in pounds per square foot and kilograms per square meter. Duct Thickness and Weight – Galvanized Steel

Galvanized Steel Gau

in

ge 8

9

10

11

12

13

14

15

0.16 81 0.15 32 0.13 82 0.12 33 0.10 84 0.09 34 0.07 85 0.07 10

Carbon Steel

m

lb/f

kg/

m

t²

m²

in

m

lb/f

kg/

m

t²

m²

4.270 6.858

33.482 0.1644 4.176 6.707

32.745

3.891 6.250

30.514 0.1495 3.797 6.099

29.777

3.510 5.638

27.527 0.1345 3.416 5.487

26.790

3.132 5.030

24.559 0.1196 3.038 4.879

23.822

2.753 4.422

21.591 0.1046 2.657 4.267

20.834

2.372 3.810

18.603 0.0897 2.278 3.659

17.866

1.994 3.202

15.636 0.0747 1.897 3.047

14.879

1.803 2.896

14.142 0.0673 1.709 2.746

13.405

Galvanized Steel Gau

in

ge 16

17

18

19

20

21

22

23

24

25

26

0.06 35 0.05 75 0.05 16 0.04 56 0.03 96 0.03 66 0.03 36 0.03 06 0.02 76 0.02 47 0.02 17

Carbon Steel

m

lb/f

kg/

m

t²

m²

in

m

lb/f

kg/

m

t²

m²

1.613 2.590

12.648 0.0598 1.519 2.440

11.911

1.461 2.346

11.453 0.0538 1.367 2.195

10.716

1.311 2.105

10.278 0.0478 1.214 1.950

9.521

1.158 1.860

9.083

0.0418 1.062 1.705

8.326

1.006 1.615

7.888

0.0359 0.912 1.465

7.151

0.930 1.493

7.290

0.0329 0.836 1.342

6.553

0.853 1.371

6.692

0.0299 0.759 1.220

5.955

0.777 1.248

6.095

0.0269 0.683 1.097

5.358

0.701 1.126

5.497

0.0239 0.607 0.975

4.760

0.627 1.008

4.920

0.0209 0.531 0.853

4.163

0.551 0.885

4.322

0.0179 0.455 0.730

3.565

Duct Thickness and Weight – Stainless Steel and Aluminium Stainless Steel Gaug e 0

1

2

3

4

5

6

7

8 9

in 0.312 5 0.281 3 0.265 6 0.250 0 0.234 4 0.218 7 0.203 1 0.187 5 0.171 9 0.156

mm

7.938

7.145

6.746

6.350

Aluminum lb/ft²

kg/m² in

13.00

63.49

5

6

11.70

57.15

7

7

11.05

53.96

3

6

10.40

50.79

4

7

5.954

9.755

5.555

9.101

5.159

8.452

4.763

7.803

4.366

7.154

3.967

6.500

lb/ft²

kg/m²

0.3249 8.252

4.585

22.386

0.2893 7.348

4.083

19.933

0.2576 6.543

3.635

17.749

0.2294 5.827

3.237

15.806

0.2043 5.189

2.883

14.076

0.1819 4.620

2.567

12.533

0.1620 4.115

2.286

11.162

0.1443 3.665

2.036

9.942

0.1285 3.264

1.813

8.854

31.73 0.1144 2.906

1.614

7.882

47.62 7 44.43 7 41.26 7 38.09 8 34.92 8

mm

Stainless Steel Gaug e

in

mm

Aluminum lb/ft²

2 10

11

12

13

14

15

16

17

18

19 20

0.140 6 0.125 0 0.109 4 0.093 7 0.078 1 0.070 3 0.062 5 0.056 2 0.050 0 0.043 7 0.037

kg/m² in

mm

lb/ft²

kg/m²

0.1019 2.588

1.438

7.021

0.0907 2.304

1.280

6.249

0.0808 2.052

1.140

5.567

0.0720 1.829

1.016

4.961

0.0641 1.628

0.905

4.417

0.0571 1.450

0.806

3.934

0.0508 1.290

0.717

3.500

0.0453 1.151

0.639

3.121

0.0403 1.024

0.569

2.777

8 28.56

3.571

5.851

3.175

5.202

2.779

4.553

2.380

3.899

1.984

3.250

1.786

2.926

1.588

2.601

1.427

2.339

1.270

2.081

1.110

1.819

8.879 0.0359 0.912

0.507

2.474

0.953

1.561

7.620 0.0320 0.813

0.452

2.205

8 25.39 8 22.22 9 19.03 9 15.86 9 14.28 4 12.69 9 11.41 9 10.15 9

Stainless Steel Gaug e

in

Aluminum

mm

lb/ft²

kg/m² in

0.874

1.432

0.792

mm

lb/ft²

kg/m²

6.990 0.0285 0.724

0.402

1.964

1.298

6.339 0.0253 0.643

0.357

1.743

0.714

1.169

5.710 0.0226 0.574

0.319

1.557

0.635

1.040

5.080 0.0201 0.511

0.284

1.385

0.556

0.911

4.450 0.0179 0.455

0.253

1.233

0.475

0.778

3.800 0.0159 0.404

0.224

1.096

5 21

22

23

24

25

26

0.034 4 0.031 2 0.028 1 0.025 0 0.021 9 0.018 7

DUCT REINFORCEMENT Maximum Duct Width (W) and Maximum Reinforcement Spacing (RS) Duct

26 gauge

24 gauge

22 gauge

wall Static Press

20 gauge or heavier

W

RS

W

RS

W

RS

W

RS

ure ½ in.

20 in.

10 ft.

wg

18 in.

NR

1 in.

20 in.

8 ft.

wg

14 in.

2 in.

20 in.

NR

20 in.

NR

20 in.

NR

10 ft.

20 in.

8 ft.

20 in.

10 ft.

20 in.

NR

12 in.

NR

14 in.

NR

18 in.

NR

18 in.

5 ft.

18 in.

8 ft.

18 in.

10 ft.

18 in.

NR

12 in.

NR

14 in.

NR

wg 3 in.

12 in.

5 ft.

18 in.

5 ft.

18 in.

5 ft.

18 in.

6 ft.

wg

10 in.

6 ft.

10 in.

NR

12 in.

NR

14 in.

NR

4 in.

Not Accepted

16 in.

5 ft.

12 in.

6 ft.

12 in.

NR

8 in.

NR

8 in.

NR

wg

DUCTWORK AIR CARRYING CAPACITY

Branch Duct

Avg. CFM @

Duct Cross-

Size

Static Pressure

section

4” Round

30 CFM

12.57 Sq-in

5” Round

60 CFM

19.64 Sq-in

2 ¼” x 10”

60 CFM

23.00 Sq-in

2 ¼” x 12”

70 CFM

27.00 Sq-in

6” Round

100 CFM

28.27 Sq-in

3 ¼” x 10”

100 CFM

33.00 Sq-in

3 ¼” x 12”

120 CFM

39.00 Sq-in

7” Round

150 CFM

38.48 Sq-in

3 ¼” x 14”

140 CFM

46.00 Sq-in

8” Round

200 CFM

50.27 Sq-in

8” x 8”

260 CFM

64.00 Sq-in

10” Round

400 CFM

78.54 Sq-in

12 “ x 8”

440 CFM

96.00 Sq-in

12”

620 CFM

113.09 Sq-in

16” x 8”

660 CFM

128.00 Sq-in

14” Round

930 CFM

153.93 Sq-in

16” Round

1300 CFM

201.06 Sq-in

PIPE SELECTION

Pipe Size

1/2"

3/4"

Steel Pipe

Copper Pipe

Flow

Heatin Coolin Flow

Heatin Coolin

Rate

g BTUH g Tons Rate

g BTUH g Tons

1.8

18,000

1.5

1.5

15,000

1.3

GPM

BTUH

Tons

GPM

BTUH

Tons

4 GPM

40,000

3.3

3.5

35,000

2.9

BTUH

Tons

GPM

BTUH

Tons

1"

8 GPM

80,000

6.7

7.5

75,000

6.3

BTUH

Tons

GPM

BTUH

Tons

1 1/4" 16 GPM 160,00

13.3

13 GPM 130,00

10.8

0 BTUH

Tons

0 BTUH

Tons

1 1/2" 24 GPM 240,00 20 Tons 20 GPM 200,00

16.7

0 BTUH 2"

0 BTUH

Tons

47 GPM 470,00 39 Tons 45 GPM 450,00 38 Tons 0 BTUH

0 BTUH

2 1/2" 75 GPM 750,00 63 Tons 80 GPM 800,00 67 Tons 0 BTUH 3"

0 BTUH

130

1,300,0

108

130

1,300,0

108

GPM

00

Tons

GPM

00

Tons

BTUH 4"

BTUH

270

2,700,0

225

260

2,600,0

217

GPM

00

Tons

GPM

00

Tons

BTUH 5"

BTUH

530

5,300,0

442

GPM

00

Tons

BTUH 6"

850

8,500,0

708

GPM

00

Tons

BTUH

 Heating capacity BTUH based on a 20 degree F temperature differential. Cooling capacity BTUH based on 10 to 16ºF temperature differential.  Cooling capacity Tons based on a 10 degree F temperature differential  Selection guide for water systems  Pipe sized for a maximum of 4 feet/100 feet pressure drop  GPM = BTUH / 10,000 (for heating units designed for 20ºF)  Temperature differential = MBH / GPM / 500  MBH = BTUH X 1,000  Ton of cooling = 12,000 BTUH CLEANROOM DESIGN Cleanroom airflow design conventionally follows the table below to decide on the airflow pattern, average velocities and air changes per hour. One has to first identify the level of cleanliness required and apply the table below. Please note that there is no scientific or statutory basis for this inference other than the explanation that the table is derived from experience over past two decades.

Clean

Airflow

Av.

Air

room

Type

Airflow

changes/h

Velocity,

r

Class

fpm 1

Unidirectio

70-100

350-650

60-110

300-600

50-90

300-480

nal 10

Unidirectio nal

100

Unidirectio nal

1,000

Mixed

40-90

150-250

10,000

Mixed

25-40

60-120

100,000

Mixed

10-30

10-40

SOUND & ACOUSTICS When trying to calculate the additive effect of two sound sources, use the approximation as below (note that the logarithms cannot be added directly). Adding Equal Sound Pressure Levels

Increase in

Increase in

Number of

Sound Power

Sound Pressure

Sources

Level

Level

( dB)

dB

2

3

6

3

4.8

9.6

4

6

12

5

7

14

10

10

20

15

11.8

23.6

20

13

26

Adding Sound Power from Sources at different Levels

Sound Power Level

Added Decibel to the

Difference between

Highest Sound Power

two Sound Sources

Level

(dB)

(dB)

0

3

1

2.5

2

2

3

2

Sound Power Level

Added Decibel to the

Difference between

Highest Sound Power

two Sound Sources

Level

(dB)

(dB)

4

1.5

5

1

6

1

7

1

8

0.5

9

0.5

10 or more

0

NOISE CRITERIA – OCCUPIED SPACES Noise Criteria (NC) are the curves based on different dB levels at different octave bands. Highest curve intercepted is NC level of sound source. See table below Occupied Spaces Area

Maximum NC

Conference Rooms

NC 35

Corridors

NC 40

Lobby

NC 40

Occupied Spaces Area

Maximum NC

Large Offices & Computer

NC 40

Rooms Small Private Office

NC 35

Notes:  The above NC levels must be attained in all octave bands.  The above NC levels may be increased for the areas equipped with fan coil units. The designer shall submit an analysis showing the expected noise levels for the prior approval of VA.  The systems must be engineered and the use of acoustic sound lining and sound attenuators should be considered to achieve the design sound levels.

AVERAGE HEAT CONTENT (BTU) OF FUELS

Fuel Type

No. of Btu/Unit

#2 Fuel Oil

140,000/gallon

#6 Fuel Oil

150,500 /gallon

Diesel

137,750/gallon

Kerosene

134,000/gallon

Electricity Natural Gas* Propane Wood (air dried)* Pellets (for pellet stoves; premium)

3,412/kWh 1,025,000/thousand cubic feet 91,330/gallon 20,000,000/cord or 8,000/pound 16,500,000/ton

Kerosene

135,000/gallon

Coal

28,000,000/ton

GLAZING PROPERTIES

Material Glass, single Glass, double glazing

“U” Value (Btu / hr-ft2-°F) 1.13 .70

Single film plastic

1.20

Double film plastic

.70

Corrugated FRP panels

1.20

Corrugated polycarbonate

1.20

Plastic structured sheet

16 mm thick

.58

8 mm thick

.65

6 mm thick

.72

Concrete block, 8 inch

.51

ROOF INSULATION The following table provides some rules-of-thumb on the cost effectiveness of adding roof insulation to an existing building. Existing Condition No insulation to R-6 R-7 to R-19 Greater than R-19

Is it cost effective to add insulation? Yes, always Yes, if attic is accessible or if built-up roof is replaced Not usually cost effective

ENERGY STAR BUILDING LABEL The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE) joined forces in establishing the Energy Star Building Label, a voluntary, performance based, benchmarking and recognition initiative. In February 1998, DOE published Energy Star target performance levels for thermal transmittance and solar heat gain factors for windows, doors and skylights.

Region

Item

Energy Star

North

Windows and

(Mostly Heating)

Doors

0.35 / -

U factor / SHGC Skylights, U

0.45 / -

factor / SHGC Central (Heating

Windows and

and Cooling)

Doors

0.40 / 0.55


0.45 / 0.55

factor / SHGC South

Windows and

(Mostly Cooling)

Doors

0.75 / 0.40


0.75 / 0.40

factor / SHGC

LIGHTING WATTAGE ESTIMATION

Location

Rule of thumb (Watts/sqft)

General Office Areas

1.5 to 3.0

Location


Private

2.0 -5.0

Conference Rooms

2.0 – 6.0

Public Places (Banks, Post offices, Courts etc) Precision Manufacturing Computer Rooms/Data Processing Facilities

2.0 – 5.0 3.0 – 10.0 2.0 – 5.0

Restaurants

1.5 – 3.0

Kitchens

1.5 – 2.5

Pubs, Bars, Clubhouses, Taverns etc

1.5 – 2.0

Hospital Patient Rooms

1.0 – 2.0

Hospital General Areas

1.5 – 2.5

Medical /Dental Centres, Clinics Residences Hotel & Motels (public places and guest rooms) School Classrooms Dining halls, Lunch Rooms, Cafeterias

1.5 – 2.5 1.0 – 4.0 1.0 – 3.0 2.0 – 6.0 1.5 – 2.5

Location


Library, Museums Retail, Department & Pharmacist Stores Jewellery Showrooms, Shoes, Boutiques etc

1.0 – 3.0 2.0 – 6.0

2.0 – 4.0

Shopping Malls

2.0 – 4.0

Auditoriums, Theatres

1.0 – 3.0

Religious Places (Churches)

1.0 – 3.0

Bowling Alleys

1.0 – 2.5

HEAT LOAD FROM OFFICE EQUIPMENT

RATE OF HEAT GAIN FROM MISCELLANEOUS APPLIANCES

SYNCHRONOUS SPEED BY NUMBER OF POLES

POLES

60 CYCLES

50 CYCLES

2

3600

3000

4

1800

1500

6

1200

1000

8

900

750

10

720

600

________________________________________________________________

Hvac Design Thumb Rules

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