Document Xz5R5xpwZRoZmRrd14w3y6j7y

American Society of Heating and .Ventilating Engineers Guide, 1930 Table 6. Conductances of Air Spaces a at Various Mean Temperatures Temp. Deo. Fahr. 0.128 or AConductance ib Spaces fob Various Width in Inches 0.250 0.364 0.493 0.713 1.00 1.500 .20 2.300 1.370 1.180 1.100 1.040 1.030 1.022 30 2.385 1.425 1.234 1.148 1.080 1.070 1.065 40 2.470 1.480 1.288 1.193 1.125 1.112 1.105 50 2.560 1.535 1.340 1.242 1.168 1.152 1.149 60 2.650 1.590 1.390 1.295 1.210 1.195 1.188 70 2.730 1.648 1.440 1.340 1.250 1.240 1?:228 80 2.819 -4.702 1.492 1.390 1.295 1.280 1.270 90 2.908 1.757 1.547 1.433 1.340 1.320 1.310 100 2.990 1.813 1.600 1.486 1.380 1.362 1.350 110 3.078 1.870 1.650 1.534 1.425 1.402 1.392 120 3.167 1.928 1.700 1.580 1.467 1.445 1.435 130 3.250 1.980 1.750 1.630 1.510 1.485 1.475 140 3.340 2.035 1.800 1.680- 1.550 1.530 1.519 ISO 3.425 2.090 1.852 1.728 1.592 1.569 1.559 Thermal Resistance of A ir Spaces, By F. B. Rowley and A. B.Algren (Journal, A. S. H. V. E., Vo!. 35.` No. 1, January, 1929). mining overall coefficients of heat transmission of walls, floors, roofs and ceilings. Computed Transmission Coefficients: As previously stated heat trans mission coefficients of many common types of building construction are given in Tables 12 to 36, inclusive, each construction being identified by a serial number. For example: The coefficient of transmission (U) of a 12-in. brick wall, furring strips, and %-in. of gypsum plaster on metal lath, is 0.216, and the number assigned to a wall of this construction is 3-B, Table 12. The coefficients in these tables were determined by computations Similar to those shown in Fig. 3, using the value of k (or C) indicated. The authorities for the conductivities used for computing these coefficients are given in Tables 7, 8, 9, 10 and 11. As in the case of the examples in Fig. 3, the average value of 1.34 given in Table 4 for/, was used for all surfaces in still air. The value of f0 for outside wall and roof surfaces was ! taken as 3 X /i, or 4.02, corresponding to a wind velocity, of approxh mately 15 miles per hour. The conductance of air spaces % in. or more in-' width was taken to be 1.10 B.t.u. per hour per square foot per degree: fahreriheit difference between the two sides enclosing the air space. (See. Table 6.) . // Problems involving the determination of the value'of U from the pon-e ductivity constants can also be solved by what is sometimes known as' the resistance method which is readily derived from the basic equation' No. 5 as follows: or ' -jr = 4- +'4- + 4- = s l* + R + *r] U J\ jo k U -------------------------------- 2 [/?j + R0 + (9) ' 20 Chapter 2--Heat Losses from Buildings Outside f,, = 4.02; Inside Outside 12" Brick, wall k =5.00 f, = I.M \t Brick wall . k = 5.00 <i-4.0L' Inside . -* Cement mortar X = 8.00 v 2'Corkboard k-0.30 Gypsum plaster k = 2.32 --fi= 1-54- U - J.+J-. + B*. . 0.2*15 I'M Am 5.00 U - . 0-S , 2lO . 0-5 . ILO . I . 0.047 1.5*151 (HO 8M SOO A.01 HI Still air both sides Outside f, = 1.34 ft = 1.34 -Jr Riqid insulation (Board form) k. = 0.33 Clapboard: k = 1.00 averaqe thickness assumed -g Gypsum plaster k=2.32 f,, = 4.02 Inside I'Sheathinq k=l.00 m actual thickness = f| Lath i lime plaster C'= 2.00 is Airspace a.=U0 \fi = 1.34 .0-170 'X1.34s-1L.10 + 0L3Q3 + 2b.3o2 . aidt. _!_+-i_ + J_AS06+jL_ l .*4 U 10 4.02 1.00 Z.00 Outside f0 = 4.02, 12 Bnck k=5.00 ' Inside feo4.01, ft-1.34 t:7u ZMollowtile C-U8 Tar^qravelroofmq k-1.32? averaqe thickness assumed^ > / t Gvpsum plaster. k - 2.11 \ J*-** )i 3" Stone concrete - 1C ^ Cement mortar k = 8.0 k = 8.30 Vf, = 1.34 . 0-221 _L+JL + R5+. + + 1.34 4.02 5.00 8.00 1.18 2.32 U = _L4-!-+A!? + 4e. 0610 1.34 402 1-325 8 30 Fig. 3. Examples Showing Method of Computing Heat Transmission Coefficients of Various -Types of Construction 21