Document XzYmR0Kb6mvyo9xr3roKOp55G

American Society of Heating and Ventilating Engineers Guide, 1934 112 Chapter 7--The Heating Load s Calculation Sheet Showing Method of Estimating Heat Losses of Table o. Building Shown in Fig. 1 Part of Building Width in Fbbt Height in Feet Net Sur face Area or Crack Length Coeffi cient Temp. Diff. Total Bru North Wall i Brick. H.m- plRstO'-------------Doors (2 in. Wood)----------- - M in. Crack-------------------------- West Wall: ,, Brick. H Poster.......... ----- Glass (Single)..-........................... Sd in. Crack.--........................ South Wall........ ............................. East WalL.------------------------------ Roof 3 in. Concrete and Slag surfaced built-up roofing------- F\oq7" 5 in. Stone Concrete on 3 in. Cinder Concrete.---------- 50 16 12 12 1 pair doors 656 144 60 120 16 15x4 9 Double Hung Windovira (15) 13S0 540 450 Same aa North Wall Same as West Wall 50 120 6000 50 120 6000 0.34 0.46 0.90 0.34 1.13 0.45 0.77 0.63 59.6 57.2 57.2 59.6 60.2 60.2 69.2 5b 13.293 3.789 1,544a 27,964. 36,734 6,095a 18,626 70.793 319,704 18.900 Grand Total of heat required for building in Biu per hour . -- ... . 517,442 This building has no partitions and whatever air enters through the cracks on the windward side must leave through the cracks on the leeward side. Therefore, only one-half of the total crack will be used in computing infiltration for each side and each end of building. bA 5 F temperature differential is commonly assumed to exist between the air on one side of a large floor laid on the ground and the ground. CONDENSATION ON BUILDING SURFACES2 . Condensation on the interior surfaces of buildings is often a serious problem. Water dripping from a ceiling may cause irreparable damage to manufactured articles and machinery. It often results in short-cir. cuiting of electric power and lighting systems, necessitating shut-downs and incurring costly repairs. It also causes rotting of wood roof struc tures, corrosion of metal roofs, and spalling and disintegration of gypsum and other types of roof decks not properly protected. Condensation is caused by the contact of the warm humid air in a building with surfaces below the dew-point temperature, and can be remedied in two ways, (1) by increasing the temperature of such surfaces above the dew-point temperature, or (2) by lowering the humidity. Dehumidification, of course, is not permissible where a high relative humidity is necessary for manufacturing processes. Hence, the only alter native is to increase the surface temperature by decreasing the inside surface resistance. This can be accomplished by increasing the velocity of air passing oyer the surface, or by increasing the over-all resistance of the wall or roof by installing a sufficient thickness of insulation. The latter method is generally used, and the thickness of insulation is determined by ascertaining the amount of resistance to be added to increase the temperature of the interior surface above the dew-point temperature for the maximum conditions involved. This in turn is based *For additional information on this subject see Preventing Condensation on Interior Building Surfaces, br Paul D. Close (A.S.H.V.E. Transactions. Vol. 36, 1930). 113