Document JvJ2oJNj8VrkpJKvzYG6Y7486

No. 996--Insulating Value of Bright Metallic Surfaces, by F. B. Rowley (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 413). No. 1026--Thermal Properties of Concrete Construction, by F. B. Rowley, A. B. Algren and Clifford Carlson (A.S.H.V.E. Transactions, Vol. 42, 1936, p. 33). ... No. 1048--Thermal Properties of Concrete Construction, by F. B. Rowley, A. B. Algren and Robert Lander (A.S.H.V.E. Transactions, Vol. 43, 1937, t P- 33). Insulating Effect of Successive Air Spaces Bounded by Bright Metallic Surfaces, Chapter 6 by L. W. Schad (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 285). Importance of Radiation in Heat Transfer Through Air Spaces, by E. R. Queer AIR LEAKAGE (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 77). Radiation and Convection Across Air Spaces in Frame Construction, by G. B. Wilkes and C. M. F. Peterson (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 351). Radiation and Convection from Surfaces in Various Positions, by G. B. Wilkes and C. M. F. Peterson (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 513). Nature of Air Infiltration, Infiltration Through Walls, Window Leakage, Door Leakage, Selection of Wind Velocity, Crack Length used for Computations, Multi-Story Buildings, Heat Equivalent of Air Infiltration Properties of Metal Foil as an Insulating Material, by J. L. Gregg (Refrigerating Engineering, May, 1932). Thermal Insulation with Aluminum Foil, by R. B. Mason (Industrial and Engineering Chemistry, March, 1933). Thermal Insulation of Buildings, Technical Paper No. 11 (American Architect, May, AIR leakage losses are those resulting from the displacement of heated air in a building by unheated outside air, the interchange taking place through various apertures in the building, such as cracks around doors and windows, fireplaces and chimneys. This leakage of air must be 1934). Heat Insulation as Applied to Buildings and Structures, by E. A. Allcut, University considered in heating and cooling calculations. (See Chapters 7 and. 8.) of Toronto, 1934. House Insulation, Its Economies and Applications, by Russell E. Backstrom (Report of the National Committee on Wood Utilization, United States Government Printing Office, 1931). Heat Transmission Through Building Materials, by F. B. Rowley and A. B. Algren, University of Minnesota Engineering Experiment Station Bulletin No. 8. Calculation of Heat Transmission, by Margaret Fishenden and Owen A. Saunders. Heating, Ventilating and Air Conditioning, by Harding and Willard, Revised Edition, 1932. Heat Transmission, by W. H. McAdams. Industrial Heat Transfer, by Shack- NATURE OF AIR INFILTRATION The natural movement of air through building construction is due to two causes. One is the pressure exerted by the wind; the other is the difference in density of outside and inside air because of differences in temperature. The wind causes a pressure to be exerted on one or two sides of a building. As a result, air comes into the building bn the windward side through cracks or porous construction, and a similar quantity of air leaves on the leeward side through like openings. In general the resis tance to air movement is similar on the windward to that on the leeward side. This causes a building up of pressure within the building and a lesser air leakage than that experienced in single wall tests as determined in the laboratory. It is assumed that actual building leakages owing to this building up of pressure will be 80 per cent of laboratory test values. While there are cases where this is not true, tests in actual buildings substantiate the factor for the general case. Mechanical ventilating systems are frequently designed to produce positive or negative pressures in an enclosure which are greater or lower than prevalent wind pressures.. In such designs, if the rate at which air is specified to be introduced to or removed from the enclosure by positive means exceeds the infiltration rate, it is common practice to use the greater value in determining the heating capacity to warm the outside air. The air exchange owing to temperature difference, inside to outside, is not appreciable in low buildings. In tall, single story buildings with openings near the ground level and near the ceiling, this loss must be considered. Also in multi-story buildings it is a large item unless' the sealing between various floors and rooms is quite perfect. This tempera ture effect is a chimney action, causing air to enter through openings at lower levels and to leave at higher levels. 116 117