Document 2jke5KOj79daJ1mXXEaDx9LxR

HEATING VENTILATING AIR CONDITIONING GUIDE 1940 112 CHAPTER 5. HEAT TRANSMISSION COEFFICIENTS AND TABLES U= 1 6.0 4.0 9.20 M J. (15 5.0 + 3.3 1 1.65 0.167 + 0.435 + 0.80 + 0.152 + 0.606 = 0.46 Btu per hour per square foot per degree Fahrenheit difference in temperature between the air on the two sides. The coefficients in the tables were determined by calculations similar to those shown in Example 1, using Fundamental Formulae 3, 4 and 5 and the values of k (or C),/i,/0 and a indicated in Table 2 by asterisks. In computing heat transmission coefficients of floors laid directly on the ground (Table 10), only one surface coefficient (/j) is used. For example, the value of U for a 1-in. yellow pine floor (actual thickness, 25/32 in.) placed directly on 6-in. concrete on the ground, is determined as follows: O = ---1-------,---0--.781----,---- 6--.0-- = 0.48 Btu per hour per square foot per degree difference T65 + 0.80 + 12.0 in temperature between the ground and the air immediately above the floor. Table 13. Coefficients of Transmission (U) of Doors, Windows, Skylights and Glass Walls Coefficients are based on d mind velocity of 16 mph, and are expressed in Btu Per hour per square foot per degree Fahrenheit difference in temperature between the air inside and outside of the door, window, skylight or tvdl A. Windows and Skylights Description u Single.-............................................................... Double.___............................................ .......... Triple............................................................... 1 13n.c 0.45 Nominal Thickness Inches i ik 2W 2H 3 B. Solid Wood Doorsb. c Actual Thickness Inches 0 Exposed Door % 1^6 We W W 2H 2% 0.69 0.59 0.52 0.51 0.46 0.38 0.33 u* With Glass Storm Door 0.42 0.38 0.35 0.35 0.32 0.28 0.25 C. Glass Walls Description Hollow glass tile wall, 6 x 6 x 2 in. thick blocks, wind velocity 15 mph, outside surface; still air. inside surface .. Still air, outside and inside surface. V 0.60 0.48 _______ ______ ____ _ vwhuhuiiuu#, uy uaiuuig turn vviuara, revisea eaiuon, 1B32. Computed using C * 1.15 for wood;/* <= 1.65 and/o " 6.0. U is sufficiently accurate to use the same coefficient of transmission for doors containing thin wood panels as that of single panes of glass, namely. 1.13 Btu per hour per square foot per degree difference between inside and outside air temperatures. *These values may also be used with sufficient accuracy for wood storm doors.' Neglect storm doors if loose and use values for exposed doors. 113