Document bawaXwL7QQMGdjzGjwewLDDy6

202 CHAPTER 9 1956 Guide : Example 3: Find the coefficient of transmission U of a frame wall consisting of stucco, 2^2-in. insulation board sheathing, 2 x 4-in. studs, gypsum lath and plaster, and with 2-in. blanket insulation between studs, for 25 mph wind velocity. Solution: From Table 7, Wall No. 20, with no insulation between studs has a value of U = 0.19. From Table 6, Col. 4, this wall with 2-in. insulation added has a value of V = 0.084. Entering Table 21 in the 15 mph column, interpolate between 0.080 and 0.090 in 15 mph column and proceed horizontally to the 25 mph column where the U value is found by interpolation to be 0.085. Table 21. Conversion Table for Wall Coefficient U for Various Wind Velocities U for 15 ra" 0.050 0.060 0.070 . 0.080 0.090 0.100 o.no 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 1.100 1.200 1.300 vTn 0 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 0.742 0.786 0.828 U for 0 to 30 mph Wind Velocities 5 0.050 0.059 0.069 0.079 0.089 0.099 0.108 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 0.939 1.010 1.080 10 1- 20 25 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 0.858 0.949 1.039 1.129 1.217 0.050 0.060 0.070 0.080 0.090 0.100 O.UO 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 1.142 1.250 1.359 0.050 0-060 0.070 0.080 0.091 0.101 O.lll 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 1.170 1.285 1.400 Wind VelOCity' 30 0.050 0.060 0.070 0.080 0.091 0.101 O.IU 0.131 0.152 0.172 0.193 0.213 0.234 0.254 0.275 0.296 0.317 0.338 0.359 0.380 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 CALCULATING SURFACE TEMPERATURES In many heating and cooling load calculations it is necessary to deter mine the inside surface temperature or the temperature of the surfaces within the structure. As the resistance of any path of heat flow is ex pressed in Fahrenheit degrees per (Btu) (hour) (square foot), the re sistances through any two paths of heat flow would be proportional to the temperature drop through these paths, and can be expressed as follows: R, (t. - tx) (6) where Rx = the resistance from the inside air to any point in the structure at which temperature is to be determined. Heat Transmission Coefficients of Building Materials 203 fts = the overall resistance of the wall from inside air to outside air. q = inside air temperature, i, = temperature to be determined. (,, = outside air temperature. Example 4-' Determine the inside surface temperature for a wall having an overall coefficient of heat transmission U = 0.25, inside air temperature 70 F, outside air temperature -- 20 F. Solution: R, = 1//, = 1/1.65 = 0.606 ft, = l/U = 1/0.25 - 4.00 Then, by Equation 6 0.606 70 - U 4.00 = 70 - (-20) U -- 56.4 F The same procedure can be used for determining the temperature at any point within the structure. A chart for determining inside wall surface temperature is given in Fig. 12 of Chapter 24, Panel Heating. REFERENCES ! Standard Method of Test for Thermal Conductivity by Means of the Guarded Hot Plate, sponsored by A.S.H.V.E., A.S.T.M., A.SJHE., and N.R.C., and approved as a Tentative Code by A.S.H.V.E. and A.S.T.M. in 1942 (A.S.T.M. designation C-177-45, Approved 1945). * Heat Transmission Through Building Materials, by F. B. Rowley and A. B. Algren (University of Minnesota, Engineering Experiment Station Bulletin, No. 8, p. 11). * Thermal Properties of Soils, by Miles S. Kersten (University of Minnesota, En gineering Experiment Station Bulletin No. 28, June 1949). 4 Radiation and Convection from Surfaces in Various Positions, by G. B. Wilkes and C. M. F. Peterson (A.S.H.V.E. Transactions, Vol. 44,1938, p. 513). Radiation Corrections for Basic Constants Used in the Design of All Types of Heating Systems, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 51. 1945, p. 213). A.S.H.V.E. Research Report No. 869--Surface Conductances as Affected by Air Velocity, Temperature and Character of Surface, by F. B. Rowley, A. B. Algren and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 444). 'Forced Convection Heat Transfer from Flat Surfaces, by G. V. Parmelee and R. G. Huebscher (A.S.H.V.E. Research Bulletin No. 3, p. 40; also published in A.S.H.V.E. Transactions, Vol. 53, 1947, p. 245). ` A.S.H.V.E. Research Report No. 1399--Heat Flow through Unshaded Glass: Design Data for Load Calculations, by G. V. Parmelee and W. W. Aubele (A.S.H.V.E. Transactions, Vol. 56, 1950, p. 371). , The Thermal Insulating Value of Airspaces, by H. E. Robinson, F. J. Powlitch iS ti"' Llill (Housing and Heme Finance Agency, Housing Research Paper No. 32, iao4, U. S. Government Printing Office). t, Thermal Test Coefficients of Aluminum Insulation for Buildings, by G. B. Wilkes> tx. Hechler and E. R. Queer (A.S.H.V.E. Transactions, Vol. 46, 1940, p. 109). Shids and Joists on Heat Flow Through Frame Walls and Ceilings, by D. Close {Healing, Piping and Air Conditioning, October, 1943, p. 529). sms* Research Report No. 1213--Heat Loss Through Basement Walls U c F. C. Houghten, S. I. Taimuty, Carl Gutberlet and C. J. Brown w.b.H.V.E. Transactions, Vol. 48, 1942, p. 369). ^TTmentaand ^ea*` Losses from Slab Floors, by R. S. Dill, Wm. C. Robinson Report BMS103^On ^at*ono* Bureau of Standards, Building Materials and Structures ,ea^ Transmission through Glass, by G. V. Parmelee (A.S.H.V.E. Research "Olletin No. 1, July 1947).