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212 CHAPTER 9 ; 1957 Guide Table 18. Coefficients of Transmission (U) of Windows, Skylights and Glass Block Walls Coefficients are ex-pressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two sides). Those for outdoor exposures are based upon the following outdoor conditions: 0 F air temperature, clear skies, no solar radiation, and 16 mph outdoor wind velocity. Section A--Vertical Glass Sheets Numbbr-of Sheets One Air space, inches.............................. Outdoor exposure......................... Indoor exposure .......................... None 1.13 0.75 K 0.61 0.50 Two 4 H 0.55 0.46 1 0.53 0.45 . 0.41 0.38 Section B--Horizontal Glass Sheets Three H 0.36 0.33 1 0.34 0.32 Heat Flow Up Heat Flow Down Number of Sheets One None Outdoor exposure................ ................... 1.40 Indoor exposure....................................... 0.96 Vi 0.70 0.59 Two M 0.66 . 0.56 1 0.63 0.56 One None 0.60 H 0.43 Two H -- 0.39 1 -- 0.38 Section C--Walls op Hollow Glass Block Description Outdoor Exposure 0.60 0.56 0.5?* 0.48 0.44 Indoor Partition 0.46 0.44 0.40 0.38 ' 0.36 Section D--Approximate Application Factors for Windows Multiply pSat Glass U Values by These Factors Window Description Single Glass Percent Glass' Factor Double Glass - Windows with Storm Sash* Percent Glass1 Factor Percent Glass1 Factor Sheets................................................. 100 1.00 100 1.00 Wood sash........................................ 80 60 80 0.90 0.80 1.00 80 0.95 80 0.90 ` 60 0.85 60 0.80 ' 80 1.20 80 l.oir Aluminum........................................ 80 1.10 80 1.30 80 1.10 (See text p. 211.) For 1 in. or greater. b See Chapter 13, Table 14 and 15 for summer load. ; r' , - :* 0 See Chapter 13, Table 14,15 and 16 for summer load. d From unpublished data recommended by ASHAE Tech. Adv. Comm, on Heat Flow Through Fenestra ? tion. 7 <=: Unit type double glazing (two lights or panes in same opening). 1 Use with U values for two sheets with 1 in. air space. ' ' ^1 * Based on area of exposed portion of sash; does not include frame or portions of sash concealed by fraO;~ b For metal storm sash or metal sash with attached storm pane. . i r- Tables 13-B and 14-B show values of U for summer calculations and outside wind velocity of 7.5 mph. Tables 11, 12 and 15 show values of.^'X for both winter and summer. Tables 9 through 12 are for indoor U values.;;' and are based upon still air. All roof coefficient tables also take into count the direction of heat flow. Care must be exercised in selecting tBp#f Heat Transmission Coefficients of Building Materials 213 Table 19. Coefficients of Transmission (/) of Solid Wood Doors Coefficients are expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two sides), and are based upon an outside wind velocity of 15 mph. Nominal thickness Inches Actual x hickness Inches Exposed.Door With Glass.Storm Door 1 H u if 2S T? I* 1A . if 0.64 0.55 0.49 0.48 0.37 0.34 0.32 0.31 2 21 3 if 0.43 2i .1 0.36 2f 0.31 0.28 0.26 0.23 Computed using k -- 1.10 for wood,/* = 1.46, fc -- 6.0, and 1.03 for air space. * A V value of 0.85 may be-used for single exposed doors containing thin wood panels or single panes of glass, and 0.39 for the same with glass storm doors. * 50 percent glass and thin wood panels Table 20. Wind Velocities U FOB 15 MPH Cf fob 0 to 30 mph Wind Velocities 10 20 25 0.050 0.060 0.070 0.080 0.090 0.100 0.110 0.130 0.150 ` 0.170 0.190 0.210 0.230 . 0.250 0.270 0.290 0.310 0.330 0.350 0.370 0.390 0.410 0.430 0.450 0.500 0.600 0.700 0.800 0.900 1.000 0.049 0.059 0.068 0.078 0.087 0.096 0.105 0.123 0.141 0.158 0.175 0.192 0.209 0.226 0.241 0.257 0.273 0.288 0.303 0.318 0.333 0.347 0.362 0.376 0.410 0.474 0.535 0.592 0.645 0.695 0.050 0.059 0.069 0.079 0.089 0.099 0.109 0.127 0.147 0.166 0.184 0.203 0.222 0.241 0.259 0.278 0.296 0.314 0.332 0.350 0.368 0.385 0.403 0.420 0.464 0.548 0.631 0.711 0.789 0.865 0.050 0.060 0.070 0.080 0.090 0.100 0.109 0.129 0.149 0.169 0.188 0.208 0.227 0.247 0.266 0.286 0.305 0.324 0.344 0.363 0.382 0.402 0.421 0.439 0.487 0.581 0.675 0.766 0.8580.949 0.050 0.060 0.070 0.080 0.090 0.100 0.110 0.131 0.151 0.171 0.191 0.212 0.232 0.252 0.273 0.293 0.313 0.333 0.354 0.375 0.395 0.416 0.436 0.457 0.509 0.612 0.716 0.821 0.927 1.034 0.050 0.060 0.070 0.080 0.091 0.101 0.111 0.131 0.151 0.172 0.192 0.213 0.233 0.253 0.274 0.295 0.315 0.336 0.357 0.378 0.399 0.420 0.441 0.462 0.514 0.620 0.728 0.836 0.946 1.058 0.939 1.010 1.080 -1.129 1.217 , 1.142 1.250 1.35_9___ t 1.170 1.2S5 ' 1.400 column is from previous tables or as calculated for 15 mph wind velocity. 30 0.056 0.060 0.070 0.080 0.091 0.101 0.1U 0.131 0.152 0.172 0.193 0.213 0.234 0.254 . 0.275 0.296 0.317 0.338 0.359 0.38Q 0.401 0.422 0.444 0.465 0.518 0.626 0.736 0.847 0.960 1.075 1.192 1.318 1.430 table which applies to the design conditions. Table 20 shows comparative values of U for other wind velocities. When this table is used for summer , values, it is necessary to enter the table at 7.5 mph which can be in terpolated between 5 and 10 mph. Any value taken from this table should rounded to two significant figures.