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American Society of Heating and Ventilating Engineers Guide, 1934
should be multiplied by the roof area and not by the ceiling area. If the unheated attic contains windows, ventilators or vertical wall surfaces, which would tend to reduce temperature in the attic to a temperature approaching or equaling the outside temperature, the roof should be neglected and only the top-floor ceiling construction and the correspond ing ceiling area taken into consideration, using the coefficients given in Tables 13 or 14. Tests made in Pittsburgh by Professor Humphreys in dicated that for this type of attic, an attic temperature should be. taken which is an average between the inside and the outside temperature.
Table 11. Coefficients of Transmission (Z7) of Frame Interior Walls and Partitions"
Coefficients ore expressed in Btu per hour per square foot Per degree Fahrenheit difference in temperature between the air on the tipo sides, and art based on stilt air (no wind) conditions on both sides.
Wall No.
TYPE OF WALL
_ Single
DOUBLE PARTITION (Finished on Both Sides of Studding)
(Finish
on'One Side of Studding)
Air Space
Between Studding
Flaked .
Gypsum Fill*
Between Studding
Rock Wool
Fill*
Between Studding.
M In. Flex ible Insula. tion Between
Studding (One Air
Space)
A
53 Wood Lath and Plaster On Studding
0.62
54 Metal Lath and Plaster* On Studding
0.69
55 Plaster Board
in.) and
0.61
Plaster* On Studding
56 H In. Rigid Insulation and 0.35 Plaster* On Studding
57 1 In. Rigid Insulation and Piaster* On Studding -
0.23
58 1H In. Corkboard and Plaster* On Studding
, 0.16
59 2 In. Corkboard and Plaster* On Studding
0.12
Computed from factors given in Table 7. ^Thickness assumed 3H in.
Plaster on meta! lath assumed % in. thick. *Plaster assumed M in. thick.
B 0.34 0.39 0.34 0.18 0.12 0.081 a. 063
c
0.11 0.11 0.10 0.083 0.066 0.052 0.045
D 0.071 0.072 ' 0.071 O.OGO 0.051 0.042 0.038
.E Q;21 0.23 0.21 0.14 0.097 0.070 0.057 .
Table 12. Coefficients of Transmission (U) of Masonry Partitions"
Coefficients ore expressed in Btu Per hour Per square foot per degree Fahrenheit difference in temperature between the air on the two sides, and are based on still air (no wind) conditions on both sides.
No. TYPE OF WALL
60 4-ln. Hollow Clay Tile 61 4-In. Common Brick 62 4-In. Hollow Gypsum Tile
Computed from factors given in Table 7.
Plain Walls
(No Plaster)
Walls Plastered on One Side
Walls ^ .Plastered on Both Sides
A
0.45 0.50 0.30
B
0.42 0.46 0.28
C
0.40 0.43 0.27
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