Document YGGMYNKBdE8Z3GXDGrJdQ04mn

166 CHAPTER 8 1954 Guide 13 The VohiinetricTncidence of Atmospheric Allergens, by O. C. Durham (Journal of Allergy, Vol. 14, September, 1943, p. 455-461). - 30 The Volumetric Incidence of Atmospheric Allergens, II: Simultaneous Measure ments by Volumetric and Gravity Slide Methods, by O. C. Durham (Journal of Allergy, Vol. 15, May, 1944, p. 226-235). 31 Air-Borne Fungus Spores as Allergens, O. C. Durham (Aerobiology, p. 32-47, Publication No. 17, American Associationfor. the Advancement of Science, Washington, D.C33 .S, a1m94p2li)n. g Devices, by H. G. DuBuy and A. Hollaender (American Journal of Medical Science, Vol. 209, February,1945, p. 172-177). 33 Ventilation Problems in' Safe Handling of Radioactive Materials, by W. W. McIntosh, paper presented at ASME Spring Meeting, March 1952. BIBLIOGRAPHY Abstracts and Bulletins (monthly, annual and special) Industrial Hygiene Founda tion, Inc., Pittsburgh, Pa. Aerobiology, Publication No. 17 (American Association for the Advancement of Science, Washington, D. C., 1942). Air Sanitation and Industrial Ventilation, by W. N. Witheridge (Detroit, Mich., 194A5m). erican Industrial Hygiene Association Quarterly (4400 Fifth Ave., Pittsburgh, Pa.A).nalytical Chemistry of Industrial Poisons, Hazards and Solvents, by M. B. Jacobs (Interscience Publishers, New York, 1941). Bibliography of Industrial Hygiene, 1900-1943 (U. S. Public Health Service Bul letin No. 289, 1945). Clouds and Smokes, by W.E. Gibbs (P. Blakiston's Son & Co., Philadelphia, Pa., 1. 92D4)e.termination and Control of Industrial Dust, by Bloomfield and DallaValle (U. S. Public Health Service Bulletin No. 217, 1935). Dust, by S. C. Blacktin (The Sherwood Press, Cleveland, 1934). (The) Environment and Its Effect upon Man (Harvard School of Public Health, BosIntodnu, s1tV9rIi3aY7l).Dust, by Drinker and Hatch (McGraw-Hill Book Co., New York, 1936). Industrial Health Engineering by A. D. Brandt (John Wiley & Sons, Inc., New YorInk,du19s4tr7i)a.l Hygiene and Toxicology, edited by F. A. Patty (Interscience Publishers, IncJ.,ouNrenwalYoofrkIn, dVuosl.trIi,al19H48ygaiendneVoaln.d11T,1o9x4ic9o).logy (monthly) (Harvard School of Public Health, Boston, Mass.). See cumulative abstract and subject indexes. Manual of Industrial Hygiene, by W. M. Gafafer, et al (U. S. Public Health Service, W.NBo.xSioauusndGearsseCs aon.,dPthheilaPdreinlpchipiale, s19o4f3R).espiration Influencing Their Action, by Hen derson and Haggard (American Chemical Society Monograph Series No. 35, Reinhold, NewOcYcuoprka,tio1n943a)n. d Health, two volumes. (International Labor Office, Washington, D, TCo.)x. icology and Hygiene of Industrial Solvents, by Lehmann and Flury, trans ited by Eleanor King and H. F. Smyth, Jr. (Williams and Wilkins, Baltimore, 1943). CHAPTER 9 HEAT TRANSMISSION COEFFICIENTS OF BUILDING MATERIALS Heat Transfer Symbols; Calculating Overall Coefficients; Conductivity of Homo geneous Materials; Soil Conductivity; Surface Conductance; Air Space Con-ductance; Practical Coefficients and Their Use; Computed Coefficients of Walls, Roofs, Ceilings and Floors; Combined Ceiling and Roof Co. efficients; Calculating Surface Temperatures THE design of air conditioning or heating systems for buildings requires a knowledge of the thermal properties of the walls enclosing the space. (The term walls in this case, includes windows, doors, ceilings, floors, roofs and skylights). The rate of heat flow through the walls under steady-state conditions at design temperatures is usually the basis for calculating the heat required. For a given wall under standard conditions the rate is a specific value designated as U, the overall coefficient of heat transmission or thermal transmittance. It may be determined by. test in a guarded hot box apparatus, or it may be computed from known values of the thermal conductance of the various components. Because testing of all combina tions of building materials is impracticable, the procedure and necessary data for calculation of the value of U are given in this chapter, together with tables of computed values for the more common constructions. HEAT TRANSFER SYMBOLS U = overall coefficient of heat transmission or thermal transmittance (air to air); the time rate of heat flow expressed in Btu per (hour) (square foot) (Fahrenheit de gree temperature difference between air on the inside and air on the outside of a wall, floor, roof or ceiling). The term is applied to the usual combinations of materials, and also to single materials, such as window glass, .and includes the surface con ductance on both sides. k = thermal conductivity; the time rate of beat.flow through a homogeneous mate rial under steady conditions through unit area per unit temperature gradient in the direction of the gradient. Its value is expressed in Btu per (hour) (square foot) (Fahrenheit degree per inch of thickness). Materials are considered homogeneous when the value of k is not affected by variation in thickness or size of sample within the range normally used in construction. C -- thermal conductance; the time rate of heat flow through a unit area of a mate rial from one of its surfaces to the other per unit temperature difference between the two surfaces. Its value is expressed in.Btu per (hour) (square foot) (Fahrenheit de gree). The term is applied to specific materials as used, either homogeneous or het erogeneous. / = film or surface conductance; the time rate of heat flow between a unit area of a surface and the surrounding air. Its value is expressed in Btu per (hour) (square foot of surface) (Fahrenheit degree temperature difference). Subscripts i and o are used to differentiate between inside and outside surface conductances, respectively. n = thermal conductance of an air space; the time rate of heat flow through a unit area of an air space per unit temperature difference between the boundary surfaces. Its value is expressed in Btu per (hour) (square foot of area) (Fahrenheit degree). Ine conductance of an air space is dependent on the temperature difference, the height, the depth, the position and the character of the boundary surfaces. The relationships are not linear, and accurate values must be obtained by test and not hy computation. ii =* thermal resistance. Its value is obtained from the reciprocal of heat trans fer as expressed by U, k, C, / or a. It is expressed in (hours) (square feet) (Fahren- 167