Document 2jn4XbMxEEv2R7rYzy8EzZkj7

214 KENNETH E. ROBINSON and C and active sweating is not required. The sharp rise in heat escape 1J evaporation above this point reflects the onset of active sweating, which is call for because R and C no longer compensate for M. Below 80 F. storage is negatifl and the magnitude of heat depletion increases as the environment becomes.pr| gressively cooler. In contrast, heat storage does not increase significantly abdi zero in warm environments, owing to the beneficial effects of sweating-:A evaporation. For the resting man in light clothing, environmental temperaturff of 80 to 85 F. are thus seen to constitute a zone of thermal neutrality wh$l conditions are not too hot or too cold. The individual has to exert no specif] effort (such as shivering or sweating) to maintain thermal balance. In this zdrjf the loss of heat from the body is distributed approximately as follows: evapoli TOO a. TJT1 'II.T' * Mill i r 500 A, S. H. V. E. mdJboBsm ,a V. E. eva _iLJ___ 1 on N 90 - 90 70 \A \,, i?K S-b .V. i. r* n co> veC on b \. t V A Pt re* MDorjtlofl-v. 7 ysy - 60 | - g liulll K / > V o i [r JAS H. . L Ota loss 30 8 ' 300 5> A S] _ * J r j. 7 VNs, w s S 01N s - -io| S 2Q 30 i) ORT-BULB TEMPERATURE. DEO FAHR (AT U PER CENTREEATIVE HUmIdITYI 40 Figure 1. Relation between metabolism, storage, evaporation, radiation plus and temperature for the clothed subject. (Reprinted by permission from Heating, Air Conditioning Guide 1957, Chapter 6.) /lilM I ' 'fM *1 - vJi tion, 20 per cent; radiation, 40 per cent; convection, 40 per. cent. Eo^aSI] "dif^^,9n.|^gr(.i^,.ol1,.^e neutral point' th!S,^^a" regulation pold within which blood flow to.the surfacbi-^ matically adjusted to promote heat flow from deep-body tissues or to mnif body heat. Below this region is the zone of metabolic regulation against peer Above it lies--thezone oi~evaporative regulation against heat; which, up^traF point of 100 per cent wetted surface, is adequate to offset the heat load ,(J| R + C). In this zone, moisture content of the air is most important. . A. EFFECTIVE TEMPERATURE SCALE AND COMFORT ZONE The four environmental factors are independently variable and mii$jl , combined in many different ways to produce the same thermal effect onpHi AIR CONDITIONING 215 faliuntease jn air velocity will offset a rise in air temperature. Extreme JS^HSciChH'be compensated by lowering the air temperature. A considerable rn`ajr temperature can be tolerated if the relative- humidity is low. 3lrl..... iSjo'f thermal conditions that induce the same thermal sensations are 90 i--i--r Air Movement or Turbulence- >9 to 25 ft per min i*C :s 70 1MA E .a 60 ,5.44-` |M tdi 50 1171V ,*? -- q^0dp--*,.f-irm__ma *omf rmS"mu.bjmec*mt!^&^-' ^ Averogo -- Avoroge Wlnltr winter Comfort Comfort 2ono Line ES3Averoftd Summer Comfort Zone Averoge Summer Comfort Une 50 60 70 80 /<: V90 100 mi.fEjaww Dry Bulb Temperature F ..Vt!V ilnVi Comfort chart for still air. Both summer and winterveomfort zones apply to the United States only. Application of winter comfort line is further limited to iu?by central station systems of the convection type," the line does not apply to .i^.jj/i'-Mljby radiant methods. Application of summer comfor}; Tline is limited to homes, wn ;-iiW5me"like, where occupants become fully adapted to the artificial air-conditions; the Jv^^ASRK'^-to-theaters^department.stores, .and the-like,iwh&eilBe..ex^8sureJs.less than 1Coptimum summer comfort line shown pertains to the northern portion of the i.c l^S^inS-ahd southern Canada; and elevations not in excess of 1000 feet above sea level. mi^TL^jqf.one degree in effective temperature should be made approximately pep five de- flrfl, ti1 tiT>'n.m north latitude. (Reprinted by permission from Transaclidns'AjSItVE', Vol. 38, mr Nj.^.thif&noequivalent conditions. The Effective Temperature....charts of the ^rtca^onety of Heating and Air-Conditioning Engineers, shown in Figures ^hTfhflygive the combinations of equivalent conditions for clothed sedentary Y.and for workers stripped to the waist. According to the ET scale, any jjjgyf of dry-bulb temperature, wet-bulb temperature, and air velocity i t Vw a*, " -.H:; 'W.,'