Document g2vbRDE7e88JJad99VENVwmk3

290 CHAPTER 12 1952. Guide Table 16. ..Instantaneous Rates or Heat Gain Due to Transmitted Direct and Diffuse or Sky Solar Radiation by a Single Sheet or 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 17 values. a00 Sun Time S. AM*** i 6 a.m. 6 p.m. H7 5 84 S5 9 3 a 10 11 12 2 1 Instantaneous Heat Gain in Btu peb (hb) (sq ft) N- ' NE . E se -s sw W::. NW` Hobiz. 25 98 108 52 23 155 190 no 16 148 205 136 16 106 180 136 17 54 128 116 18 20 59 78 18 -19 19 35 5 5 5 5 17 10 10 10 10 71 14 13 13 13 137 21 15 15 15 195 34 17 16 16 241 45 19 18 . 18 267 49 35 19 19 276 a u 5 a.m. 7 p.m. 66 75 3 26 .16 7 116 149 6 131 195 2 67 124 z8 4 14 . 129 205 156 09 Q 10 0 11 12 3 2 1 15 79 180 162 16 31 127 148 17 18 58 113 17- 17 19 64 0000 1 7 6 6 6 25 11 10 10 10 77 18 12 12 12 137 42 14 14 14 188 69 16 16 16 229 90 23 . 17 17 252 98 64 .. 19 17 259 5 a.m. 7 p.m. 20 54 54 20 33 33 6 66 25 128 149 81 8 . 7 7 7 34 a7 S 12 139 . 197 136 12 10 10 10 80 Z8 4 13 107 202 171 32 12 . 12 12 129 09 3 14 54 176 183 72 14 14 14 173 Q 10 e 11 2 1 15 18 124 174 no 16 15 15 206 16 16 57 143 136 42 16 16 227 12 16 16 18 98 ' 144 96 . 18 16 234 N NW W sw. s SE . E NE Hobiz. other design temperatures are given in Table 26 in a later section, Effect of Deviation from Design Conditions. Tables 16 and 17 may be used for other types of glass with good accuracy, by using the factors given in Table 18. Table 16 values are multiplied by the appropriate factor given in Table. 18 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, Table117 values are multiplied by the appropriate coefficient of X. listed in Table 18. Second, Table 19 values are multiplied by the appropriate coefficient of Y listed in Table 18, and added to the first value. All convection and radiatipn gain values for double glass were computed for a J-in. air space. No great error is involveil in cooling load estimates if: these are used for double:glass with other air spaces. .' Example 14: Find the total instantaneous heat gain through a single sheet of regular plate glass in a southwest wall at 2 p.m. sun time and 40 deg north latitude on. August 1. The maximum dry-bulb temperature for desigo is 98 F.; the atmos-. phere is clear. The indoor temperature is 75 F. . Solution: From Table 16 the heat gain due to transmitted radiation is 148 Btu per (hr) (sq ft) for common window glass; from Table 18, the factor for regular plate1 glass is 0.87. The coefficient of X in Table 18 is 1.0, while A is found from Table 17 for common window glass for the same hour, orientation and latitude. The co efficient of Fin Table'18 is0.25, while the F value is found from Table 19for asouth- Cooling Load . 291 Table 17. Instantaneous Rates of Heat'Gain by Convection and Radiation prom i Single Sheet of Unshaded Common Window Glass For Clear Atmospheres and 18 Deg Declination, North (August-1) For 76 F Indoor Temperature Note: For total instantaneous heat gain, add these values to the Table ,16 values. Sun . Time Dbt- Nobth Buub Latitude Deo F Degrees 5 a.m. 6 7 8 9 10 11 12 1 p.m. 2 3 `4 5' 6 7 8 9 74 74 75 77 80 83 87 90 30,40,50 93 94 95 94 93 91 87 85 83 Instantaneous Beat Gain in Btu peb (hb) (sq ft) N NE . E SE S SW W NW -1 0 -1 1 --1 1 -1 0 -j -1 -1 -1 -1 -1 -1 0 3320000 2. 5 6 5 3 2 2 2 5 7986555 8 9 11 11 10 8 8 8 13 *13 15 16 15 14 13 13 17 17 17 18 19 18 17 17 20 20 20 21 22 22 22 20 21 21 21 21 23 24 24 22 22 22 22 22 24 26 26 24 21 21 21 21 22 25 25 24 20 20 20 20 20 23 24 23 18 18 18 18 18 19 20 20 13 13 13 13 13 13 13 13 11 11 11 11 11 11 ll 11 8 8888888 Hob. -1 0 2 5 8 13 18 21 25 26 26 24 22 18 13 11 8 west wall at 2:00 p.m. and 40 deg north latitude. The correction for design dry-bulb temperature is found from Table 26 to be 1.0 Btu per (hr) (sq ft) per degree difference from 95 F design temperature. The total instantaneous heat gain is, from Equa tion 7a, q = 0.87 X 148 + 1.0 X 24 + 0.25 X 27 + 1.0 (98 - 95)' = 162.7 Btu per (hr) (sq ft). Design Tables for Rolled Figured Glass Tables 20 and 21 give design values of instantaneous rates of heat gain for a number of common patterns, of single vertical sheets of rolled figured glass. The tables are for a solar declination of 18 deg, which corresponds to a nominal August 1 day, and are based upon the solar intensity values for a clear, atmosphere as given in Table 5. The values are given1 in terms of corrections to apply to Tables 16 and 17. The heat gain due to-transmitted solar, radiation is found by multiplying the Table T6 values by the approximate percentages given in Table 21. To obtain instan taneous rates of heat gain by convection and radiation, Table 19 values are multiplied by1 the appropriate value of Y from Table 20 and then added to Table 18. Application Factors to Apply to Tables 16,17 and 19 to Obtain Instantaneous Rates of Heat Gain for Various Types of Single t .j...Flat Glass and Combinations of Two Sheets of Flat Glass ' Spaced at J in. . .' Glass Normal Ikcxdencb .Tbansmxitakcb Factob to Afplt to Table 16 Factob to . Aptly to Table 17 . Single Common Window. Single Regular Plate Single Heat Absorbing Plate Double Common Window Double Regular Plate Heat Absorbing Plate Outdoors! Regular Plate*Indoors * - / 0.87. 0.77 0.41 0.76 0.60 0.35 1.00 . -0.87 0.46* 0.85 0.66* 0.37* 1.0(X)b.+0.0(F) 1.0(X) + 0.25(F) 1.0(X) + 1.00(F) 0.6(X) + 0.10(F) 0.6(X) -f-0.55(F) 0.6(X) + 0.75(F) b Cr precision, increase factors 10 percent when class is in the shade. X values are Table 17 values. y values are Table 19 values.