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American Society of Heating and Ventilating Engineers Guide, 1932 Table 5-A. Summary of Heat Loss Calculations for Residence Shown in Fig. 2 Room or "Space No. Room Glass Trans mission Losses Other Trans mission Losses Infiltra tion Losses Total i 7,100 2,640 9,040. 4,640 8,970 742 25,110 8,022 1,060 3,300 663 5,023 1,370 3,718 807 5,895 1,888 1,854 1,312 1,436 4,320 3,900 7,520 7,190 3,773 3,558 1,445 8,776 8 3,960 2,900 4,070 3,765 1,445 1,660 9,475 8,325 1,450 920 1,660 4,030 1,450 1,940 1,660 5,050 12 I Attic (heated)................................... 3,040 28.021 1,125 32,186 Grand Total of heat required for building in Btu per hour at 8 F with 126,602 a 17-mile southwest wind-.................................................................. ........ Table 5-B. Heat Loss Calculation Sheet for Living Room (Fig. 2) Part of Building Exposure Net Surface Area or Crack Length Co Temp.' efficient Difference Net Btu Exposure Factor Total Btu Wall------------Glass..--.......... Crack H6m-a E E E Wallb.............. Crack H6 >n-- S S S Wall........ ........ Crack He in W W W Over Floor............... Basement 75.6 15.0 19.0 127.6 42.0 40.0 75.6 15.0 19.0 241.0 0.263 1.13 0.5 0.263 1.13c 2.50 0.263 1.13 0.50 : 78 78 78 78 78 78 78 78 78 0.339 33' 1,550 1,320 (742)4 2,620 3,710 7,800 1,550 1,320 (742)d 2,700 1.15 1.15 1.15 1.15 1.15 Grand Total of heat required for room in Btu per hour at -- 8 F with a i./-mue 1,550 1,320 3,010 4,260 8,9704 1,780 1,520 2,700 25,110 aWindows weatherstripped. bChimney figured as part of wall, that is, of the same construction. cTransmission coefficient taken same as glass for entire door. dThree sides of this room are exposed and therefore only the wall having the greatest infiltration loss is used in estimating the total leakage for the room. If the infiltration loss for the south side of the room con taining the two outside doors had been less than half the total infiltration loss for the room, then half the total leakage would have been used. Air temperature.at floor assumed 65 F. Air temperature in basement assumed 32 F. 22 Chapter 3 HEAT TRANSFER THROUGH MATERIALS AND CONSTRUCTIONS Transmission Coefficients by Test; Transmission Coefficients by Computation; Areas where Transmission Losses Occur; Calcula tionsfor Transmission Losses; Condensation on Building Surfaces; Sun Effect on Buildings. THIS chapter relates primarily to the loss of heat by conduction through solid materials, such as the exterior walls, roof, glass, etc. of a building, under equilibrium conditions. These transmission losses, as they are termed, are computed by taking into account the heat transmission coefficients of the various structural members involved. (See par. 5, p. 11): These coefficients may be determined experimentally by test, or they may be calculated with sufficient accuracy when certain physical constants are known. TRANSMISSION COEFFICIENTS BY TEST The standard method of testing built-up wall sections is by means of the guarded hot-box.1 The Nicholls Heat Meter2 may be used for testing actual walls of buildings. If the hot-box method is used, tests are usually run under still-air conditions, which means there was no wind movement during the test over the surfaces of the wall. In practice, some wind movement over the exterior surface of the wall should always be allowed for; hence, still-air coefficients cannot be used in actual work as they do not provide for the normal wind movement over the outside of the building in the locality in question during the heating season. Moreover, still-air transmission coefficients cannot be corrected to provide for moving-air conditions by multiplying by a single constant factor. It would be obviously impossible to determine the air-to-air heat trans mission coefficients of every type of wall construction in use with the heat meter or the hot-box on account of the great amount of time involved. Hence, the method of computing the coefficients from fundamental con stants must be resorted to in most cases, but heat-meter and the hot-box tests can be used to good advantage in checking the accuracy of the computed values. lSee Standard Code jar Heat Transmission through Walls (A.S.H.V.E. Transactions, Vol. 34. 1928). See Measuring Heat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.S.H.V.E. Transactions, Vol. 30. 1924). 23