Document B5X6VDB1R7DRQx2a1ym0V2dKJ

120 CHAPTER 9 1959 Guide U Vofcm* Without Added tnsuhtioa Table 16 .... Determination of U Value Resulting from Addition of Insulation or Air Spaces to Uninsulated Building Sections* (Continued) ______________ PART C. CEILINGS--HEAT FLOW UP` (WINTER CONDITION) _______ Fibrous insufotion nUaMi--(aches Ona Air Space of effective mfrWfy"-E Two Air Space! of Effective EmmiVity" E Three Air Spaces of Effective Emitavdy* E H1 0.82" 0.20 0.05 0.82 0.20 0.05 0.82 0.20 0.05 Coll 234 6 7 8 9 10 11 12 . 13 14 0.70 0.60 0.50 0.45 0.305 0.284 0.260 0.246 0.195 0.186 0.175 0.168 0-113 0.110 0.106 0.104 0.080 0.078 0.076 0.075 0.690 0.588 0.488 0.438 0.472 0.417 0.361 0.331 0.403 0.362 0.318 0.295 0.427 0.385 0.339 0.316 0.262 0.244 0.224 0.212 0.216 0.204 0.189 0.180 0.307 0.284 0.258 0.243 0.180 0.171 0.160 0.154 0.139 0.131 0.126 0.40 0.35' 0.30 0.28 0.230 0.212 0.192 0.184 0.161 0.152 0.142 0.138 0-101 0.097 0.093 0-091 0.074 0.072 0.069 0.068 0.389 0.340 0.292 0.272 0.300 0.269 0.237 0.224 0.270 0.244 0.215 0.203 0.288 0.260 0.230 0.217. 0.199 0.185 0.168 0.161 0.170 0.158 0.145 0.140 0.227 0.209 0.189 0.181 0.138 0.125 0.121 0.115 0.104 0.26 0.24 0.22 0.20 0.175 0.166 0.156 0.145 0.133 0.127 0.121 0.115 0.089 0.087 0.084 0-081 0.066 0.065 0.064 0.062 0.253 0.234 0.214 0.195 0.211 0.199 0.186 0.173 0.19i 0.179 0.166 0.154 0.204 0.191 0.178 0.164 0.154 0.146 0.137 0.128 0.134 0.128 0.120 0.114 0.172 0.163 0.153 0.143 0.120 0.109 0.104 0.101 0.097 0.093 0.088 0.18 0.16 0.14 0.12 0.134 0.123 0.111 0.098 0.108 0.100 0.092 0.083 0.078 0.074 0-069 0.064 0 060 0.057 0.054 0.051 0.176 0.156 0.137 0.118 0.159 0.146 0.132 0.118 0.141 0.128 0.115 0.101 0.150 0.136 0.120 0.105 0.119 0.109 0.099 0.088 0.106 0.098 0.090 0.080 0.132 0.121 0.109 0.096 0.097 0.090 0.083 0.075 0.084 0.073 0.068 0.10 0.08 0.085 0.073 0 058 0.047 0.099 0.105 0.088 0.090 0.076 0.071 0.082 0.067 0.062 0.070 0.062 0.050 0.042 0.079 0.091 0.074 0.073 0.064 0.061 0.067 0.058 0.056 * For construction with six spaces s* insulation, coefficients Are based oa National Bureau af Standards date in JTewtef Bumrtk Paper No. 32 (U. S. Government Printing Office, Washington, D. C.). I Based on a temperature difference of 73 deg F from air to air, and a mean temperature of 40 F. k 17 value taken from Tables It, 12,13-A, 14-A, and IS, in which it is assumed that the eirapece between joists * above the suspended ruling i$ nonreSective (E -- 0.83), and is 8 in. thick. 1 Thermal conductivity of fibrous or bulk insulation taken as 0.27 Btu per (hr) (sq ft) (F deg per in.). For values of effective emissivity B of air space, eee Table 3, Section B. " Certain U values is Column 0 differ from Column 1 because they ore adjusted to the specific temperature drop across the air apace in question as affected by the V value at the construction. PART 0. CEILINGS--HEAT FLOW DOWN0 (SUMMER. CQND/T/ON) U Value9 Without Added Inadotiaa Fibrous Insulation* Thickness ladies 1 23 One Air Space cf^ffectrve Emitavityf E 0.82 0.20 0.05 Two Air Spaces of Effective Emissivity'-B Three Air Spaces af Effective Emissivity' B 0.82 0.20 0.05 0.82 0.20 0.05 Col 1 2 3 4 5 6 7 8 9 to u 12 n . u 0.70 0.60 0.50 0.45 0.305 0.2S4 0.260 0.246 0.195 0.186 0.175 0.168 0.113 0.110 0.106 0.104 0.080 0.078 0.076 0.075 0.704 0.602 0.501 0.450 0.269 0.252 0.231 0.220 0.119 0.116 0.112 0.108 0.423 0.384 0.340 0.316 0.144 0.139 0.133 0.128 0.061 0.060- 0.059 0.058 0.306 0.284 0.260 0.246 0.103 0.100 0.097 0.095 0.046 0.046 0.044 0.40 0.35 0.30 0.28 0.230 0.212 0.192 0.184 0.161 0.152 0.142 0.138 0.101 0.097 0.093 0.091 0.074 0.072 0.069 0.068 0.400 0.350 0.300 0.280 0.206 0.192 0.175 0.168 0.105 0.100 0.095 0.093. 0.291 0.264 0.234 0.222 0.123 0.118 0.112 0.109 0.057 0.056 0.055 0.054 0.230 0.213 0.193 0.185 0.092 0.090 0.086 0.085 0.044 0.043 0.042 0.042 0.26 0.24 0.22 0.20 0.175 0.166 0.156 0.145 0.133 0.127 0.121 0.115 0.089 0.087 0.084 0.081 0.066 0.065 0.064 0.062 0.260 0:240 0.220 0.200 0.160 0.152 0.144 0.135 0.090 C.087 0.084 0.081 0.209 0.195 0.182 0.168 0.105 0.102 0.098 0.094 0.054 0.053 0.052 0.050 0.176 0.167 0.157 0.146 0.083 O-OSO 0.078 0.075 0.041 0.040 0.040 0.039 0.18 0.16 0.14 0.12 0.134 0.123 0.111 0.098 0.108 0.078 0.100 . 0.074 0.092 0.069 0.083 Q.064 0.060 0.057 0.054 0.061 0.180 0.160 0.140 0.120 0.125 0.115 0.104 0.093 0.077 0.073 0.069 0.063 0.154 0.139 0.124 0.108 0.0S9 0.084 0.078 0.072 0.049 0.047 0.045 0.042 0.135 0.124 0.111 0.098 0.072 0.068 0.064 0.059 0.038 0.038 0.037 .0.035 0.10 0.08 0.085 0.073 0.058 0.047 0.099 0.080 0.056 0.091 0.064 0.039 0.084 0.054 0.033 0.070 0.062 0.050 0.042 0.079 0.068 0.048 0.074 0.054 0.034 0.070 0.046 ` 0.030 * Based on a temperature difference of IS F deg from air to air, and a mean temperature of 100 F. 9 U value taken from Tables It, 12,1S-B, 14-B, and IS, in which it is assumed that the air spaoe between joists or above the suspended ceiling is nonreflective (E -- 0.83), and w 8 in. thick. q Thermal conductivity of fibrous or bulk insulation taken as 0.27 Btu per (hr) (sq ft) (F deg per in.). 1 For values of effective emissivity S of air space, see Table 3. Section B. Heat Transmission Coefficients of Building Materials 121 Table 16 .... Determination -of U Value Resulting from Addition of Insulation to Uninsulated Building Sections (Concluded) (For use with Tobias 13A and 136) PART E. FLAT ROOFS AND CEILINGS WITH ROOF DECK Conductance C af Roof-Deck Intuhlion U Value of Roof without Roof-Deck insulation* 0.12 0.15 0.19 0.24 0.36 0.72 UU UUU U 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.50 0.60 0.70 0.05 0.07 0.08 0.08 0.09 0.06 0.08 0.09 0.09 0.10 0.07 0.08 0.10 0.11 0.12 0.07 0.09 0.11 0.12 0.13 0.08 0.11 0.13 0.15 0.16 0-09 0.12 0.16 0.19 0.21 0 09 0.09 0.10 0.10 0.10 0.10 0.11 0.12 0.12 0.12 0.12 0.13 0.14 0.14 0.15 0.14 0.15 0.16 0.17 0.18 0.|18 0.19 0.21 0.22 0.24 0.24 0.26 0.29 0.33 0.35 * luterpolatioo or mild extrapolation may be used. CORRECTION FOR FRAMING Correction for parallel heat flow through framing and in sulated areas may be made by use of Fig. 6. Correction for the effect of framing should. be applied after final U, and U, values have been obtained for a given construction. In many cases this correction may be omitted. Example 7: Consider a frame wall with 2-in. blanket insula tion which has a {/< value of 0.08. By calculation it is found that heat loss from the area backed by framing members (/,) is 0.13. UJUi is 1.63. From Fig. 6 if 15 percent of wall area is backed by framing, the value U^JU, - 1.1. is therefore 1.1 X 0.08 - 0.088. s-x '25 -20 -1 .. , 5 oel l-T I M I II I I I II I I I I II I I I I I L _ O 050 l.o 1.50 2.0 2.5 a0 U./Ui -- overage U value for building taction. Ui -- U value for area between framing member!. U, = U vafva for area bockad by. framing aembers. S -- percentage of area bockad by framing memben. Fig. 6 .... Correction for Effect of Framing in Insulated Building Sections VENTILATED ATTICS--HOW TO USE TABLE 17 Tabic 17 is intended to be used with Tabic 11, PartD of Table 16, and Fig. 6, or when ceiling resistance is known. Its purpose is to determine the resistance to heat flow of the attic space under various conditions of ventilating air temperatures and rates, ceiling resistance, roof or sol-air temperatures, and surface emismties.u Ventilating air temperature is the out door design temperature. The total resistance, l/U, obtained by adding the ceiling and attic resistances can be converted to a U value so that the heat gain may be calculated. The applicable temperature dif ference is that difference between room air and sol-air tem perature or between room air and roof temperatures. (See footnote d, Table 17.) Table 17 may be used lor both pitched and fiat residential roofs over attic spaces. When there is an attic floor, the ced ing resistance should be that which applies to the complete ceiling-floor construction. All values in Table 16, Part D, include the resistance of a noQ-reflective surface facing the attic space. Therefore, if separate calculations are made, include only the value of a . non-reflective surface and not the value of a reflective surface in determining ceiling resistance. The use of Table 17, Part B, will account for this reflection surface. Example 8; Determine the heat gain for a 1000 sq ft eeiling of %-in. gypsum board and light weight aggregate plas ter, with no flooring above, when insulated with a 2-in. foil- enclosed fibrous blanket. The blanket is installed so as to form a reflective air space between the ceiling and the blanket. The attic has a gable roof which meets the ventilation requirements in Table 3, Chapter 10. (Use ventilation rate of 0.1 cfm per sq ft.) Design temperatures are: indoor air -- 75 F, outdoor air -- 95 F, and sol-air -- 160 F. Solution: From Table 11, for beat.flow down, the V value for this ceiling G3 without insulation is 0.40. Referring to Table 16, Part D, with the value 0.40 in Column 1, find Ui = 0.101 in Column 4; enter Column 1 at 0.101 and find Ui TM 0.056 in Column 8. Correct for framing (8 in. joists on 16 in. centers) from Fig. 6 and find corrected ceiling coefficient U, ~ 0.059; R, - 17.0. By interpolation in Table 17, Part B, using 95 F ventilation air and 160 F sol-air temperatures, the effective attic resistance The overall coefficient for the combined ceiling and attic is: 1 U, 0.04 Rt+ Re 17.0 + 8.2 Heat gain V. A (f, -- k) - 0.04 X 1000 X (160-75) - 3400 Btuh COMBINED CEILING AND ROOF COEFFICIENTS If the attic space between the ceiling and roof is unheated and not ventilated, the combined coefficient from room air be low the ceiling to exterior air can be calculated from the fol lowing formula: _1_ _i_ Rt Ua ^ nUr (4) The combined coefficient V is the reciprocal of Rr , or where U - 1/flr (5) U = combined coefficient to be used with eeiling area. Hr = total resistance of ceiling and roof. Ut, -- coefficient of transmission of ceiling. U, *= coefficient of transmission of roof., n -- ratio of roof area to ceiling'area. It should be noted that the overall coefficient- U should be multiplied by the ceiling area to determine heat loss, and not /