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
200 sq. ft. of floor area per
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
180 sq. ft. of floor area per
School Classroom
ton
Bowling Alley
250 sq. ft. of floor area per ton 1.5 – 2.5 tons per alley
Department Store Basement
350 sq. ft. of floor area per
Main Floor
ton
Upper Floor
300 sq. ft. of floor area per
Small Shop
ton 400 sq. ft. of floor area per ton 225sq. ft. of floor area per ton
Dress Shop
280 sq. ft. of floor area per
Application
Average Load
Drug Store
ton
Factory (precision
150 sq. ft. of floor area per
manufacturing)
ton 275 sq. ft. of floor area per ton
Groceries – Supermarket
350 sq. ft. of floor area per
Hospital Room
ton
Hotel Public Spaces
280 sq. ft. of floor area per ton 220sq. ft. of floor area per ton
Motel
400 sq. ft. of floor area per
Auditorium or Theatre
ton 20 people per ton
Shoe Store
220 sq. ft. of floor area per
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
U factor / SHGC Skylights, U
0.45 / 0.55
factor / SHGC South
Windows and
(Mostly Cooling)
Doors
0.75 / 0.40
U factor / SHGC Skylights, U
0.75 / 0.40
factor / SHGC
LIGHTING WATTAGE ESTIMATION
Location
Rule of thumb (Watts/sqft)
General Office Areas
1.5 to 3.0
Location
Rule of thumb (Watts/sqft)
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
Rule of thumb (Watts/sqft)
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
________________________________________________________________