Document qXNL1ERKV88rRnD79VQV92Bn

American Society of Heating and Ventilating Engineers Guide, 1934 Table 7. Recommended Conductivities and Conductances for Computing Heat Transmission Coefficients CCoonndduucctatinvciteiessaarereinedxipcraetsesdedbiynaBstleurispkesr <ho)uranpder Jsequfaorer ftohoettPheZr dkec^reeorF^ahi^refnthZeitehde,TnJ ptTncL Material ^Brick, Common. Brick. Face___ _ - Cefhent Mortar-.. Cinqer Concrete.. Cinder Blocks* (8 in.)--......... Cinder Blocks* (12 in.) Concrete Blocks* (8 in.)------Concrete Blocks* (12 in.).------ConcreteGypsum Fiber Concrete...----Hollow Clay Tile (4 in.)-------Hollow Clay Tile (6 in.)*____ Hollow Clay Tile (8 in;)*.____ Hollow Clay Tile (10 in.)*___ Hollow Clay Tile (12 in.)*.___ Hollow Clay Tile (16 in.)*.___ Hollow Gypsum Tile (4 in.)__ Insulations.. Corkboard. Flexible.. Flaked Gypsum (24 lb) Rigid Insulation______ Rock Wool Plaster (Gypsum)___ Plaster Board (\i in. Conductivity | OR | Conductance H Material 5.00 9.2 12.00 5.20 0.62* 0.51* 1.0* 0.80* 12.00 1.66 1.00* 0.64* 0.60* 0.58* 0.40* 0.31* 0.46* Plaster Board (tf in.)_ Roofing.. Asbestos Shingles______________ ..-- Asphalt or Composition Roofing. Built-up* % in. thick.----------- ..... Slate Shingles... Wood Shingles (see woods)| Stone_________ _________ .____ I Stucco. Tile or Terrazzo___ I Wood Lath and Plaster. Woods... 1-in. Fir sheathing, building paper and yellow pine lap siding--------------- 1-in. Fir sheathing and building paper 0.30 0.27 0.48 0.33 0.30 3.3 3.73* Yellow pine lap siding. Yellow pine or fir..... .... Maple or oak.. Shingles, wood___ :[ Air 8paces.................. *' Surfaces, still air (Ji) Surfaces, 15 mpb ........... ........ . CONDUCTtVITY OR Conductance 2.82* 6.00* 6.50* 3.53* 10.37 12.50 12.00 12.00 2.50* 0.50* 0.82* 1.28* 0.80 1.15 .28* 1.10* 1.65* .00* *For thickness or condition stated, not per 1 in. One air cell in the direction of heat flow. *The 6-in.. 8-in. and 10-in hollow tile figures are based on two cells in the direction of heatiflow. The 12-in. hollow tile is based on three ceils in the direction of heat flow. The 16-in. hollow tile consists of one 10-in. and one 6-in. tile, each having two cells in the direction of heat flow. and hence, the amount of heat absorbed by radiation by each square foot of roof surface is less than is given off by radiation by each square foot of ceiling surface. Example 2. Determine the combined coefficient of transmission of a roof constructed of asbestos shingles applied over wood sheathing on rafters,' an unheated attic; and a wood lath and plaster ceiling, based on a roof having a'one-third pitch, for which the value of n is 1.2. Ur = 1 ----i---- l 1 6.0 2.20 ^ 6.0 0.781 " 0567 0.80 Uce = 0.685 1.65 T 2.20 ^ 2.50 Substituting these values in Equation 6: UT. = l 2~0X.560756X7 04.6- 805685 = n0 o28onBt.U per . hUr P square p, t, op, rooJ,&rea' ... degree difference in temperature between the air near the under side of the ceiling and the outside air. If the uriheated attic space between the roof and ceiling has no dormers, windows or vertical wall surfaces, the combined coefficients may be used for determining the heat loss through the roof construction between the attic and top-floor ceiling, but it should be noted that these coefficients Chapter 5--Heat Transmission