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American Society of Heating and Ventilating Engineers Guide, 1928
Chapter; I--Calculating the Heat Losses from Buildings
The air temperature just below roof is higher than that at the breathing
line. Mean height of roof is 16 -f 4 = 20 ft., or it is 20 -- 5 -- 15 ft. above breathing line. Allowing 2 per cent per foot above 5 ft., or 2 X 15 = 30 per cent, makes the under roof temperature = 1.30 X 60 = 78 deg.
fahr.
,
Floor: The 5 in. concrete floor is laid on the ground, and hence there is
only one surface coefficient K= 1.34 = Average for surface in still air
(Table 3)
V = __J---- -- = 0.745
-------------h --
1.34 T 8.3
The air temperature at floor level = 60 -- 5 = 55 deg. fahr.
Windows and Doors: Wood sash and doors with single thickness of glass. Take coefficient U for glass as 1:13 B.t.u. per sq. ft. per degree per hour for heat transmission (Table 12-A). Doors are solid wood 2 in. thick and coefficient U = 0.382 B.t.u. per sq. ft. per degree per hour (Table 12-B).
Infiltration: Window crack assumed fg in. and doors at xj in. By Table 14 (Part I) for a 10 mile wind velocity the leakage per foot of crack is 85 c.f. hr. for a plain window. The heat equivalent per hour, per degree
I is 85 X .075 X 0.24 = 1.53 B.t.u.
and allowing for an 11 mile wind the factor becomes 1.53 X = 1.68 (see preceding note). Allow twice this for door crack or 2 X 1.68 = 3.36.
Calculation Sheet
Entire Building
(See Fig. 7)
! Coeffic.
Area Trans.
Building
Expo- Width Height Sq. Ft. and Temp. Net
Material
sure
in Ft. in Ft. or Lin. Infilt. Diff.
B.t.u.
B.t.u.
Ft.
Concrete and Tile__ N
A X 50 8A 213 0.304 74.0 4,800
1.15
5,520
i Fig. 7. Elevation of Factory Building
N Doors (2 in. wood)_ N
A in. Crack.--.......... N
50 16 12 12
1 pair doors
656 0.304 59.4 144 0.382 56
60 3.36 56
11.850 3,080
11,300
1.15 1.15
A* X 1.15
13,630 3,550
6,500
29,200
iV
V =:
J_ 4X, +
-Lx X, +
Fl C,
4^
-in*. C,
4-
^5-
+
*4
c.
-
i
1,1.9
1 , 0-5
1.34 + 4.02 '1" 8.3 ~r 1.14 8.0
0.5 2.32
= 0.304
The air temperature at the mean height of inside walls is greater than at breathing line. Mean height of walls is 16 -5- 2 = 8 ft., which 8 -- 5 = 3 ft. above breathing line. Allowing 2 per cent per foot above,5'ft., or 2X3 = 6 per cent, makes the mean air temperature 1.06 X 60 = 63.4 deg. fahr. The triangular areas in the, end. wall are practically at the
mean height of the roof at which level the air temperature is 78 deg, fahr.
Concrete and Tile.... W
Glass (Single) >6 in. Crack_______
wW
South Wall_________ Same
as N
East Wall......._....... Same
as W
Roof, 3 in. Concrete
and slag-surfaced
built-up roofing.;.. No
Ceiling
Floor, 5 in. Stone
Concrete
On
Dirt
120 16
15 X 4
9
Double Hung
Windows (15)
See above . See above
52.5 120 50 120
1380 0.304 59.4 540 1.13 59.4 450 1.68 59.4
24,950
36,200 44,900
6300 0.610 74 285,000
6000 0.745 5
22,350
1.15 1.15
A* X 1.15
K*
A*
28,700 41,600 25,800
96,100
25,380
83,600
None None
285,000 22,350
Grand total of heat required for building in B.t.u. per hour at + 4" with 11-mile Southwest wind............................................................................ ............... 541,630
Roof: 3 in. concrete (stone), with slag surface built-up roofing. U -- 0.010 (Roof No. 2ifLc, Table 10-A)
JVofej.--(1) This building has no partitions and whatever air enters through the cracks on the windward s,de must leave through the cracks on the leeward side. Therefore, only one-half of the total crack wui be used in computing infiltration for each side and each end of building.
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