Document 3ea48mbNkLBbe7akzw59bvkva

I' iI Jill-: ;S:j !' f. ; .J ! 4 4 A.S.H.V.E. Research Reports: ', / No. 852--Effects of Air Velocities on Surface Coefficients, by F. B.'Rowley, A. B. Algren and J. L Blackshaw (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 123). ' - No. 895--Wind Velocity Gradients Near a Surface and Their Effect on Film Conductance, by F. C. . . Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 301). No. 914--Surface Coefficients as Affected by Direction of Wind, by F. B. Rowley and W. A. Eekley (A:S.H.V.E. Transactions, Vol. 38, 1932, p. 33). No. 915--Conductivity of Concrete, by F. C. Houghten and Carl Gutberlet (A.S.H.V.E. Transac No. 964--tTihoensH, eVaotl.C3o8,n1d9u3c2t,ipvi.ty47o).f Wood at Climatic Temperature Differences, by F. B. Rowley (A.S.H.V.E. Transactions, Vol. 39. 1933, p.' 329). No. 996--Insulating Value of Bright Metallic Surfaces, by F. B. Rowley (A.8.H.V.E. Transactions No. 1026--VThoel.r4m0a, l19P3r4o,ppe.rt4ie1s3)o. f Concrete Construction, by F. B. Rowley, A. B. Algren and Clifford Carlson (A.S.H.V.E. Transactions} Yol. 42, 1936, p. 33). No. 1048--Thermal Properties of Concrete ponstruction, by F. B. Rowley, A. B. Algren and Robert Lander (A.S.H.V.E. Transactions.'Vol; 43, 1937, p. 33). ' No. 1351--Overall Coefficients for Flat Glass Determined under Natural Weather Conditions, by G. V; Parmelee and W, W. Aubele (A;S.H.V:E, Transactions, Vol. 55, 1949, p. 39). Radiation and Convection Across Air Spaces in Frame Construction, by G. B. Willies and C, M. F. Peter- sonIn(Asu.Sla.Htin.Vg.EE.ffTecrta' nosf a' Scutciocnesss,ivVeplA. 4ir3,S1p9a3c7e, pB. o3u5n1d).e-.d, b. y B,, right Metallic Surfa.c.e.s., .by L...W., Schad (A.STh.He.rVm.Eal. CTornadnusacctivtiiotynso,f VWool.od3,7,b1y93J1.,Dp.. 2M8a5)c.Lean (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 323). The Specific Heat of Thermal Insulating Materials, by G. B. Wilkes and C. O, Wood (A.S.H.V.E. Trans actHioenast, LVoossl.S4t8u,d1ie9s42in, pF.o4u9r3I)d. entical Buildings to Determine the Effect of Insulation, by D. B. Anderson (A.SE.fHfe.cVt.oEf. CTerialinnsgaIcntsiuolnasti,oVnoul.p4o8n, 1S94u2m, pm.e4r7C1)o. mfort, b y T. D. Phillips {National Bureau of Standard*, RepTohret.rBmMaSl 5In2s, uJlualtyion1,M1a94d0e).o..f Wood-Base Materials, Its Application and Use in Houses, by L. V. Teesdals (U.HSe. aFtoTrerastnPsrmodisusciotsnL-TahbrooruagtohryBRueilpdoirntgNMo.aRte1r7ia4l0s,,.bOyctFob, eBr.1R9o49w).ley and A. B. Algren {University of Minne sotaB, EuinldgiinnegeIrnisntgUEatxiopne^ribmye. nPtaSutlaItIi.o.Cn lBp^u^llAettinnerNtcoa. n8T).ccAnwol Society, Chicago, 4th Edition, 1951). ! . CHAPTER 10 ' MOISTURE IN BUILDING CONSTRUCTION Properties of Water in Air; Water in Building.Materials; Movement of Moisture in Materials; Vapor Transmission; Permeance and Testing'; Visible Condensation; Concealed Condensation in Heated Buildings; Control of Concealed'Condensation; Condensation in Cooled Structures THE behavior of moisture is too often overlooked or given, scant at tention in the design and construction of buildings. It is present as a vapor-in all air and as adsorbed moisture in most building materials. may be present also at times in the free liquid state or as ice, in the solid state, within the range of temperatures encountered in many buildings. Problems involving-moisture may arise from changes in-moisture content, from the presence of excessive moisture, or from effects associated with its changes in state. Of particular interest here is the change from the vapor to the liquid or solid state, known :as condensation. This may be associated with a re duction of temperature with time; or may occur as a result of migration of water vapor to regions of lower temperature. Moisture problems involv ing condensation are therefore most likely to occur mi buildings in any climate in which there is a source :of water vapor at temperatures above normal, or in cooled structures, and in buildiigs in cold: climates. Moisture problems in residences occur in winterand become increasingly important as homes are built smaller and tighter. Water vapor originates from such necessary living requirements as cooking, laundering, bathing, and the breathing and perspiration of people. In a typical family of four, the average daily production of water vapor from these .sources may be as much as 25 lb, and may be much greater where such appliances as humidifiers, automatic washers, and dryers are used.1 Another large source of water vapor is sometimes the bare earth in a crawl space or base-.ment. All this water vapor must escape from the dwelling. It PROPERTIES OF WATER VAPOR IN AIR Water vapor in air is a gas which occupies all the space, along with the air present. In many ways, the water vapor can act independently of the aw, since in general its properties do not depend on the presence of the aw- It exerts its own vapor pressure, and can move about through air. in space, or move through materials under differences in its own vapor swlHSUT' lnf^Pendently of the air. However, when the air is moved aff t r *s h^ted or cooled, the water vapor present is similarly ected, so that it is usually necessary to consider it as a part of an airVaPor mixture. lcnT^6 properties of mixtures of air and water vapor are relatively well in tlf11 an^ are c?ea^ with fully in Chapter 3, Thermodynamics. Changes the v;6 ProPerfies with heating and cooling can be followed readiiy with TM 01 a psychrometric chart, shown in outline in Fig. 1. The satura-