Air-Conditioning Systems

Heating and Cooling load Calculation Tables

table 1. Outdoor air requirements for ventilation

Estimated OccupancyOutdoor air requirements
function per 100sq. Meter per person, L/s
floor area Smoking non-smoking
offices 7 10 2.5
meeting and waiting spaces 60 17.5 3.5
Lobbies 30 7.5 2.5
by Stocker and Jones

table 2. ASHRAE dust spot efficiencies (1-µm particles)³

Filter Type Efficiency range, % Application

Viscous Impingement 5 to 25 dust and lint removal
Dry Media:
1 Glass Fiber, Multi ply 25 to 40 same as above and for some
cellulose, wool felt industrial applications
2 Mats of 3 to 10µm 40 to 80 building recirculated and fresh air
fiber 6 to 20mm thick systems
3 Mats of 0.5 to 4µm 80 to 98 hospitals surgeries, clean rooms
fiber (usually glass) special applications
Electrostatic (depending on 20 to 90 pollen and airborne particles
type)
by Stocker and Jones

table 3. Design Temperature data

Winter Summer
2.5% dry bulb/ coincident August Daily Average
City 97.5% dry bulb, °C wet bulb, °C °C
Albuquerque, N. Mex. -9 33/16 24
Atlanta, Ga -6 33/23 26
Boise, Idaho -12 34/18 22
Boston, Mass. -13 31/22 22
Chicago, Ill. -18 33/23 23
Columbus, Ohio -15 32/23 23
Dallas, Tex. -6 36/24 29
Denver, Colo. -17 33/15 22
El paso, Tex. -5 37/18 27
Great Falls, Mont. -26 31/16 19
Houston, Tex. 0 34/25 28
Las Vegas, Nev. -2 41/18 31
Los Angeles, Calif 4 32/21 21
Memphis, Tenn. -8 35/24 27
Miami, Fla. 8 32/25 28
Minneapolis, Minn. -24 37/23 22
New Orleans, La. -4 33/26 28
New York, NY. -9 32/23 24
Phoenix, Ariz. 1 42/22 32
Pittsburgh, Pa. -14 31/22 22
Portland, Oreg. -4 30/20 20
Sacramento, Calif. 0 37/21 26
Salt LakeCity, Utah -13 35/17 24
San Francisco, Calif 4 22/17 17
Seattle, Wash. -3 28/19 18
Spokane, Wash. -17 32/17 20
St. Louis, Mo. -13 34/24 25
Washington, D.C. -8 33/23 25
by Stocker and Jones

table 4. Thermal Resistance of unit areas of selected building materials at 24°C mean temperature

1/k, m-K/W R,m²-K/W

Exterior Material
Face brick 0.76
Common brick 1.39
Stone 0.55
Concrete block, sandand gravel aggregate, 200mm 0.18
Lightweight aggregate, 200mm 0.38
Lightweight aggregate, 150mm 0.29
Stucco 1.39
Siding, asbestos cement, 6mm, lapped 0.04
Asphalt insulating, 13mm 0.14
Wood plywood, 10mm 0.1
Aluminum or Steel, backed with 0.32
insulating board, 10mm

Sheating
Asbestos cement 1.73
Plywood 8.66
Fiberboard, Regular Density, 13mm 0.23
Hardboard, medium density 9.49
Particle Board, 10mm 7.35

Roofing
Asphalt Shingles 0.08
Built Up Roofing, 10mm 0.06

Concrete
Sand and Gravel aggregate
Lightweight aggregate
 Insulating Materials
Blanket and batt, mineral fiber, 75-90mm 1.94
Blanket and batt, mineral fiber, 135-165mm 3.35
Board and slab, glass fiber, organic bond 27.7
Expanded Polysterene, Extruded 27.7
Cellular polyurethane 43.8
Loose fill, mineral fiber, 160mm 3.35
Cellulosic 21.7 - 25.6

Interior Materials
Gypsum or Plaster board, 15mm 0.08
Gypsum or Plaster board, 16mm 0.1
Plaster Materials, Cement Plaster 1.39
Gypsum Plaster, Lightweight, 16mm 0.066
Wood, soft (fir, pine, etc.) 8.66
Hardwood (maple, oak, etc.) 6.31

Air Resistance
Surface, still air (surface emissivity of 0.9)
horizontal, heat flow up 0.11
Surface, still air (surface emissivity of 0.9)
horizontal, heat flow down 0.16
Surface, still air (surface emissivity of 0.9)
vertical, heat flow horizontal 0.12
Surface moving air, heating season, 6.7 m/s 0.029
Surface moving air, cooling season, 3.4 m/s 0.044
Air Space, Surface emissivity of 0.8
horizontal 0.14
vertical 0.17
Air Space, Surface emissivity of 0.2
horizontal 0.24
vertical 0.36

Flat Glass
U, W/m² · KƗ
Summer Winter
Single glass 5.9 6.2
Double glass
6-mm air space 3.5 3.3
13-mm air space 3.2 2.8
Triple glass
6-mm air space 2.5 2.2
13-mm air space 2.2 1.8
Storm windows, 25 to 100-mm air space 2.8 2.3
Ɨ includes inside and outside air film resistance
by Stocker and Jones
table 5. Infiltration constants for infiltration
Quality of construction a b c
Tight 0.15 0.01 0.007
Average 0.2 0.015 0.014
Loose 0.25 0.02 0.022
by Stocker and Jones

table 6. Cooling load factors for lighting

No. of hours Fixture XƗ, Fixture YƗ,
after lights hours of operation hours of operation
are turned on 10 16 10 16
0 0.08 0.19 0.01 0.05
1 0.62 0.72 0.76 0.79
2 0.66 0.75 0.81 0.83
3 0.69 0.77 0.84 0.87
4 0.73 0.8 0.88 0.89
5 0.75 0.82 0.9 0.91
6 0.78 0.84 0.92 0.93
7 0.8 0.85 0.93 0.94
8 0.82 0.87 0.95 0.95
9 0.84 0.88 0.96 0.96
10 0.85 0.89 0.97 0.97
11 0.32 0.9 0.22 0.98
12 0.29 0.91 0.18 0.98
13 0.26 0.92 0.14 0.98
14 0.23 0.93 0.12 0.99
15 0.21 0.94 0.09 0.99
16 0.19 0.94 0.08 0.99
17 0.17 0.4 0.06 0.24
18 0.15 0.36 0.05 0.2
by Stocker and Jones

table7. Heat gain from occupants

Activity Heat gain, W Sensible heat gain, %

Sleeping 70 75
Seated, quiet 100 60
Standing 150 50
Walking, 3 km/h 305 35
Office work 150 55
Teaching 175 50
Retail shop 185 50
Industrial 300 - 600 35
by Stocker and Jones
table 8. Space per occupant
Type of space Occupancy
Residence 2 - 6 occupants
Office 10 - 15 m² per occupant
Retail 3 - 5 m² per occupant
School 2.5 m² per occupant
Auditorium 1.0 m² per occupant
by Stocker and Jones

table 9. Sensible Heat Cooling load factors for people

hours after
each entry TOTAL HOURS in space
into space 2 4 6 8 10 12 14 16
1 0.49 0.49 0.50 0.51 0.53 0.55 0.58 0.62
2 0.58 0.59 0.60 0.61 0.62 0.64 0.66 0.70
3 0.17 0.66 0.67 0.67 0.69 0.70 0.72 0.75
4 0.13 0.71 0.72 0.72 0.74 0.75 0.77 0.79
5 0.10 0.27 0.76 0.76 0.77 0.79 0.80 0.82
6 0.08 0.21 0.79 0.80 0.80 0.81 0.83 0.85
7 0.07 0.16 0.34 0.82 0.83 0.84 0.85 0.87
8 0.06 0.14 0.26 0.84 0.85 0.86 0.87 0.88
9 0.05 0.11 0.21 0.38 0.87 0.88 0.89 0.90
10 0.04 0.10 0.18 0.30 0.89 0.89 0.90 0.91
11 0.04 0.08 0.15 0.25 0.42 0.91 0.91 0.92
12 0.03 0.07 0.13 0.21 0.34 0.92 0.92 0.93
13 0.03 0.06 0.11 0.18 0.28 0.45 0.93 0.94
14 0.02 0.06 0.10 0.15 0.23 0.36 0.94 0.95
15 0.02 0.05 0.08 0.13 0.20 0.30 0.47 0.95
16 0.02 0.04 0.07 0.12 0.17 0.25 0.38 0.96
17 0.02 0.04 0.06 0.10 0.15 0.21 0.31 0.49
18 0.01 0.03 0.06 0.09 0.13 0.19 0.26 0.39
by Stocker and Jones

table 10. Maximum Solar heat gain factor for sunlit glass, W/m²

N/shade NE/NW E/W SE/SW S Hor.

32° North Latitude
Dec 69 69 510 775 795 500
Jan, Nov 75 90 550 785 775 555
Feb, Oct 85 205 645 780 700 685
Mar, Sept 100 330 695 700 545 780
Apr, Aug 115 450 700 580 355 845
May, July 120 530 685 480 230 865
June 140 555 675 440 190 870
 N/shade NE/NW E/W SE/SW S Hor.
40° North Latitude
Dec 57 57 475 730 800 355
Jan, Nov 63 63 480 755 795 420
Feb, Oct 80 155 575 760 750 565
Mar, Sept 95 285 660 730 640 690
Apr, Aug 110 435 690 630 475 790
May, July 120 515 690 545 350 830
June 150 540 680 510 300 840

table 11. Shading Coefficients

Thickness No indoor Venetian Blinds Roller Shades

Type of glass mm Shading dark light dark light
Single Glass
Regular Sheet 3 1.00 0.64 0.55 0.59 0.25
Plate 6 to 12 0.95 0.64 0.55 0.59 0.25
Heat absorbing 6 0.70 0.57 0.53 0.40 0.30
10 0.50 0.54 0.52 0.40 0.28
Double Glass
Regular Sheet 3 0.90 0.57 0.51 0.60 0.25
Plate 6 0.83 0.57 0.51 0.60 0.25
Reflective 6 0.2-0.4 0.2-0.33
table 12. Cooling load factors for glass with interior shading, north latitudes table 14. Cooling

Solar Window facing

Time h N NE E SE S SW W NW HOR. Roof
6 0.73 0.56 0.47 0.3 0.09 0.07 0.06 0.07 0.12 type
7 0.66 0.76 0.72 0.57 0.16 0.11 0.09 0.11 0.27
8 0.65 0.74 0.8 0.74 0.23 0.14 0.11 0.14 0.44 1
9 0.73 0.58 0.76 0.81 0.38 0.16 0.13 0.17 0.59 2
10 0.8 0.37 0.62 0.79 0.58 0.19 0.15 0.19 0.72 3
11 0.86 0.29 0.41 0.68 0.75 0.22 0.16 0.2 0.81 4
12 0.89 0.27 0.27 0.49 0.83 0.38 0.17 0.21 0.85 5
13 0.89 0.26 0.24 0.33 0.8 0.59 0.31 0.22 0.85 6
14 0.86 0.24 0.22 0.28 0.68 0.75 0.53 0.3 0.81
15 0.82 0.22 0.2 0.25 0.5 0.83 0.72 0.52 0.71 1
16 0.75 0.2 0.17 0.22 0.35 0.81 0.82 0.73 0.58 2
17 0.78 0.16 0.14 0.18 0.27 0.69 0.81 0.82 0.42 3
18 0.91 0.12 0.11 0.13 0.19 0.45 0.61 0.69 0.25 4
5
6
table 13. Solar position angles for twenty-first day of month

Solar time, A.M. table 15. Cooling

Month Angle 5 6 7 8 9 10 11 12
32° north latitude
Dec β 10 20 28 33 35 Roof
ɸ 54 44 31 16 0 type
Jan, Nov β 1 13 22 31 36 38
ɸ 65 56 46 33 18 0
Feb, Oct β 7 18 29 38 45 47
ɸ 73 64 53 39 21 0
Mar, Sep β 13 25 37 47 55 58
ɸ 82 73 62 47 27 0
Apr, Aug β 6 19 31 44 56 65 70
ɸ 100 92 84 74 60 37 0 G
May, Jul β 10 23 35 48 61 72 78
ɸ 107 100 93 85 73 52 0
Jun β 1 12 24 37 50 62 74 81
ɸ 118 110 103 97 89 80 61 0
40° north latitude
Dec β 5 14 21 25 27
ɸ 53 42 29 15 0
Jan, Nov β 8 17 24 28 30
ɸ 55 44 31 16 0
Feb, Oct β 4 15 24 32 37 39
ɸ 72 62 50 35 19 0
Mar, Sep β 11 23 33 42 48 50
ɸ 80 70 57 42 23 0
Apr, Aug β 7 19 30 41 51 59 62
ɸ 99 89 79 67 51 29 0 F
May, Jul β 2 13 24 35 47 57 66 70
 ɸ 115 106 97 87 76 61 37 0
Jun β 4 15 26 37 49 60 69 73
ɸ 117 108 100 91 80 66 42 0
7 6 5 4 3 2 1 12
Solar time, P.M.

C
table 14. Cooling - load temperature difference for flat roofs, K

Mass per Heat

Solar Time
unit area, capacity
kg/m² kJ/m² · K 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Roofs without suspended ceilings
35 45 3 11 19 27 34 40 43 44 43 39 33 25 17 10
40 75 -1 2 8 15 22 29 35 39 41 41 39 34 29 21
90 90 -2 1 5 11 18 25 31 36 39 40 40 37 32 25
150 120 1 0 2 4 8 13 18 24 29 33 35 36 35 32
250 230 4 4 6 8 11 15 18 22 25 28 29 30 29 27
365 330 9 8 7 8 8 10 12 15 18 20 22 24 25 26
Roofs with suspended ceilings
45 50 0 5 13 20 28 35 40 43 43 41 37 31 23 15
50 85 1 2 4 7 12 17 22 27 31 33 35 34 32 28
100 100 0 0 2 6 10 16 21 27 31 34 36 36 34 30
150 130 6 4 4 4 6 9 12 16 20 24 27 29 30 30
260 240 12 11 11 11 12 13 15 16 18 19 20 21 21 21
360 340 13 13 13 12 12 13 13 14 15 16 16 17 18 18

table 15. Cooling - load temperature difference for sunlit walls

Mass per Heat

Orientation
unit area, capacity Solar
kg/m² kJ/m² · K time N NE E SE S SW W NW
7 4 15 17 10 1 1 1 1
8 5 20 26 18 3 3 3 3
9 5 22 30 24 7 4 5 4
10 7 20 31 27 12 6 6 6
11 8 16 28 28 17 9 8 8
12 10 15 22 27 22 14 10 10
13 12 14 19 23 25 21 15 12
50 15 14 13 15 17 20 26 28 23 15
15 13 15 17 18 24 33 31 20
16 14 14 16 16 21 35 37 26
17 14 14 15 15 17 34 40 31
18 15 12 13 13 14 29 37 31
19 12 10 11 11 11 20 27 23
20 8 8 8 8 8 13 16 14
CLTD_max 15 22 31 28 26 35 40 31
7 1 3 4 2 1 1 2 1
8 2 8 9 6 1 1 2 1
9 3 13 16 10 2 2 2 2
10 4 16 21 15 4 3 3 3
11 5 17 24 20 7 4 4 4
12 6 16 25 23 11 6 6 6
13 8 16 24 24 15 10 8 7
200 130 14 9 15 22 23 19 14 11 9
15 11 15 20 22 21 20 16 12
 16 12 15 19 20 22 24 22 15
17 12 15 18 19 21 28 27 19
18 13 14 17 17 19 30 32 24
19 13 13 15 16 17 29 33 26
20 13 12 13 14 15 25 30 24
CLTD_max 13 17 25 24 22 30 33 26
7 2 3 3 3 2 4 4 3
8 2 5 6 4 2 3 3 3
9 3 8 10 7 2 3 3 3
10 3 11 15 10 3 3 4 3
11 4 13 18 14 5 4 4 4
12 5 14 20 17 7 5 5 5
13 6 14 21 19 10 7 6 6
300 230 14 7 14 21 20 14 10 8 7
15 8 14 20 20 16 14 11 9
16 10 15 19 20 18 18 15 11
17 10 14 18 19 19 21 20 14
18 11 14 18 18 18 24 24 18
19 12 14 17 17 17 25 27 21
20 12 13 15 16 16 24 27 21
CLTD_max 12 15 21 20 19 25 27 21
7 3 4 5 5 4 6 7 6
8 3 4 5 5 4 5 6 5
9 3 6 7 5 3 5 5 4
10 3 8 10 7 3 4 5 4
11 4 10 13 10 4 4 5 4
12 4 11 15 12 5 5 5 4
13 5 12 17 14 7 6 6 5
390 350 14 6 13 18 16 9 7 6 6
15 6 13 18 17 11 9 8 7
16 7 13 18 18 13 12 10 8
17 8 14 18 18 15 15 13 10
18 9 14 18 18 16 18 17 12
19 10 14 17 17 16 20 20 15
20 11 13 17 17 16 21 22 17
CLTD_max 11 14 18 18 16 21 23 18
7 5 6 7 7 6 9 10 8
8 4 6 7 6 6 8 9 7
9 4 6 8 7 5 7 6 6
10 4 7 9 7 5 7 7 6
11 4 8 11 9 5 6 7 5
12 4 10 13 10 5 6 7 5
13 5 10 14 12 6 6 7 6
530 450 14 5 11 15 13 8 7 7 6
15 6 12 16 14 9 8 8 6
16 6 12 16 15 11 10 9 7
17 7 12 17 16 12 12 11 9
18 8 13 17 16 13 14 13 10
19 9 13 16 16 14 16 16 12
20 9 13 16 16 14 18 18 14
CLTD_max
CLTD_max 9 13 17 16 14 18 20 15