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HEATING VENTILATING AIR CONDITIONING GUIDE 1940
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Table 4. Solar Radiation Impinging against Walls having several Orientations, and A Horizontal Surface.
For 40 Deg Latitude on the twenty-first of July.
Intensity of Solar Radiation. Btu per Sq Ft per Hour
Tims
Northeast
4:31 0 5:00 14 6:00 72 7:00 143 8:00 143
9:00 10:00
11:00 12:00
104 46
) -no y -on
&00 4.-00
5*00
6:00
7:00 7:29
East
0 14 80 180 211
192 143 75
Southeast
South
Southwest
West
Northwest
Horizontal Surface
0 5 40 112 155 8
0 1 19 82
162
168 46 156 77 121 95
73 103
15 73
15 95 : 121 75
77 156 143
46
46 168 192 104
8 155 211 143
213
26s
284 293
284 258 213 152
112 180 143 ' 40 80 72
5 14 14
000
82 19
1
0
Table 5. Solar Radiation Impinging against Walls having several Orientations, and a Horizontal Surface.
For l/6 Deg Latitude on the twenty-first of July.
Sun Time
Northeast
4:26 0 5:00 : 25 6:00 89 7:00 149 8:00 140
9:00 10:00 11:00
12:00
. 92 33
i -nn
.1:00 4:00
^00 6*qo 7.-00
Intensity of Solar Radiation, Btu pbr-Sq Ft per Hour
East Southeast
South Southwest
West
Northwest
Horizontal Surface
00 24 9 99 52 194 125 219 171
22
0
26 90 156
194 183 i44 171 75 139
91
.65 98 121
128
3291
210 251' 274 . 282
32 121 139
75 .
98 171 144
33
65 183 194
92
22 171 219 140
274
251 210.
156
' 125 194 144 52 99 89 9 24 25
90
26 2
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CHAPTER 8. COOLING LOAD
Since the amount of solar intensity actually transmitted through a surface depends upon the nature of the exterior surface of wall of roof construction, it is necessary, in order to determine actual amount of solar heat transmission, to apply correction factors to the values of (7). Solar radiation factors and solar absorption coefficients have been determined8 as indicated in Fig. 2 and Table 6 respectively.
The solar heat conduction through a wall or roof exposed to the sun may be expressed by the formula:
where
HR = A Fa I
(2)
Hr = solar heat transmission, Btu per hour. A -- area of wall or roof, square feet.
F = radiation factor--percentage (expressed as a decimal) of the absorbed solar radiation which is transmitted to the inside (Fig. 2).
a = absorption coefficient--percentage (expressed as a decimal) of the incident solar radiation which is absorbed by the surface (Table 6).
I -- intensity of solar radiation striking surface, Btu per hour per square foot (Tables 2, 3, 4 and 5).
The total amount of heat conducted through a wall exposed to the sun is the sum of ift and HR from Formulas 1 and 2.
*A Rational Heat Gain Method for the Determination of Air Conditioning Cooling. Loads, by F. H. Faust, L. Levine, and F. O. Urban (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 327).
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