Document k6gkmoBe9eMZO4OGqdeKmY69B
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CHAPTER 13
1956 Guide
Table 12. Tbansmittances and Absorptances of Common Window Glass for Direct and Diffuse Solar Radiation
Angle op Incidence, 0, DEG
50
oo
|
Single Sheets
TWO AIR-SPACED SHEETS
D D td aD td Outdoor Sheet Indoor Sheet
For Direct Radiation
0.87 0.87 0.86 0.84
0.79 0.67 0.42 0.0
0:05 0.05 0.06 0.06
0.06 0.06 0.06 0.0
0.76 0.76 0.74 0.72
0.66 0.52 0.25 0.0
0.06 0.06 0.06 0.07
0.07 0.07 0.07 0.0
0.04 0.04 0.04 0.05
0.05 0.05 0.05 0.05
0.79
For Diffuse or Sky Solar Radiation | 0.06 | 0.6S | 0.07
| 0.05
dry-bulb temperature cycle, with a 95 F maximum as tabulated. The total heat gain is the sum of the Table 13 and Table 14 values. In preparing Table 14, convection and radiation heat exchange were combined, and a combined surface conductance of 4.0 used. Corrections to be applied for other design temperatures are given in Table 23 in a later section,/Effect
of Deviation from Design Conditions.
Tables 13 and 14 may be used for other types of glass with good accuracy, by using the factors given in Table 15. Table 13 values are multiplied by the appropriate factor given in Table 15 to obtain heat gain due to trans mitted solar radiation. For glasses having a transmittance for normally incident radiation differing from the table values, factors may be found by linear interpolation. To obtain instantaneous rates of heat gain by con vection and radiation, two steps are required. First, Table 14 values are multiplied by the appropriate coefficient of X listed in Table 15. Second, Table 16 values are multiplied by the appropriate coefficient of Y listed
Fio. 3. Convection and Radiation Heat Flow for Vertical Single Glass:
Cooling Load
301
Table 13. Instantaneous Rates of Heat Gain Due to Transmitted Direct and Diffuse or Sky SoDar Radiation bt A Single Sheet of Unshaded Common Window Glass
For Clear Atmospheres and 18 Deg Declination, North (August 1)
Note: For total instantaneous heat gain, add these values to the Table 14 values.
a t it u d e 1L
Sun Time
Instantaneoub Heat Gain in Btu per (hr) (sq ft)
AM - r
N " NE
E SE
S SW W Nff Horiz.
sc 6 a.m 6 p.m.
s7
5
o
Z9
3
a 10
Q o
11 12
2 1
25 98 108 23 155 190 16 148 - 205 16 106 180
17
18 18 '
54 . 128 20 59 19 19
5 a.m. 7 p.m. .6 6
5
Z
3 26
16 14
a 9 11
3
1 --
15 16 17 17
5 a.m. 7 p.m. *6
75
Z
20 25 12 13
a9 n
3
14 15 16 16
7 116 149 129
79 31 . 18 17
. 54 128 139 107
54 18 16 16
6 131 195 205
180 127 58 19
54 149 197 202
176 124 57
18
__ r PM --
N Nff | W
, 52 110 136 136
116 78 35
2, 67 124 156
.- 162 148 113 64 -
20 81 136 171
183 174 143 96
5 10 14 21
34 45 49
0 7 II 18
42 69 90 98
3. 8 12 32
72 110 136 144
SW S
10 13 15
17 19 35
0 6 10 12
14 16 23 64
3 7 10 12
14 16 42 96
SE
13 13 137 15 15 195
16 16 241 18 18 267 19 19 276
6 10 12 12 137
14 16 17 19 17 259
10 12 12 129
14 15 16 18 16 234
E NE | Horiz.
Table 14. Instantaneous Rates of Heat Gain by Convection and Radiation from a Single Sheet of Unshaded Common Window Glass
For Clear Atmospheres and 18 Deg Declination, North (August 1) For 80 F Indoor Temperature
Note: For total instantaneous heat gain, add these values to the Table 13 values.
Sun Time
Dry- North Bulb Latitude Deg F Degrees
N
5 a.n 6 7
10 11 12
1 p.m. 2
3 4 5
74 --6 74 --5 75 --5 77 --3 80
83 87 90 30,40,50 93 94
95 94 93 91 87
3 8 12 15 16
17 16 15 13
85 6 83 3
Instantaneous Heat Gain in Bto peb (hr) (sq ft)
NE
--6 --1 --2
0 2
4 8 12 15 16
17 16 15 13 8
6 3
E
--6 --4 --2
1 4
6 10 12 15 16
17 16 15 13 8
6 3
SE
--6 --5 --3
0 3
6
11
13
.
16
16
17 16 15
13 8
6 3
S
--6 --5 --5 --2
1
5 10 14 17 18
19 -17 15 13
8
6 3
SW
--6 --6 --5 --3
0
3 9 13 17 19
21 20 18 14 8
6 3
W
--6 --6 --5 --3
0
3 8 12 17 19
21 20 19 15 8
6 3
NW
--6 --6 --5 --3
0
3 8 12 15 17
19 19 18 15 8
6 3
Hor.
--6 --5
0 3
16
21
21
17 13 8 6 3