Document J3RMRJYVQyn49Mrg0Y6zZnMyK

HEATING VENTILATING AIR CONDITIONING GUIDE 1944 Within a few years, however, they find themselves reacting as natives to the new environment. The adaptive level changes somewhat with the season29. There are also marked differences between the sexes. In the cold zone the thickness of thermal insulating tissues of women is almost double that of men, although the sensory responses to cold are similar. In the hot zone, the threshold of sweating and skin temperature levels are higher for women. Finally, the thickness and insulating value of the clothing worn is an important factor in the determination of the comfort level. Observations Indicating Comfort EFFECTIVE TEMPERATURE INDEX Sensations of warmth or cold depend, not only on the temperature of the . surrounding air as registered by a dry-bulb thermometer, but also, upon the temperature indicated by a wet-bulb thermometer, upon air movement and upon radiation effects. Dry air at a relatively high temperature may feel cooler than air of considerably lower temperature with a high moisture content. Air motion makes any moderate condition ' feel cooler. Radiation to cold or from warm surfaces is another important factor under certain conditions. . Combinations of temperature, humidity, and air movement which induce the same feeling of warmth are called thermo-equivalent condi- The Reactions of the Clothed Human Body to Variations in Atmospheric Humidity, by C.-E. AWinslow. L. P. Herrington and A. P. Gagge (American Journal of Physiology, VoL 124, December, 1938, . p. 692). 58 CHAPTER 2. PHYSIOLOGICAL PRINCIPLES tions. A series of studies50 at the A.S.H.V.E. Research Laboratory, Pittsburgh, established the equivalent conditions met with in general air conditioning, work. This scale of thermo-equivalent conditions not only indicates the sensation of warmth, but also to a considerable degree determines the physiological effects on the body induced by heat or cold. For this reason, it is called the effective temperature scale or index, and it denotes sensory heat level. Effective temperature is an empirically determined index of the degree of warmth perceived on exposure to different combinations of temperature, humidity, and air movement. It was determined by trained subjects who compared the relative warmth of various air conditions in two adjoining conditioned rooms by passing back and forth from one room to the other. The numerical value of the index for any given air conditions is fixed by the temperature of slowly moving (15 to 25 fpm air movement) saturated air which induces a like sensation of warmth or cold. Thus, any air condition has an effective temperature of 60 deg, when it induces a sensation of warmth like that experienced in slowly moving air at 60 deg saturated with moisture. The effective temperature index cannot be measured directly but is determined by the dry- arid wet-bulb tempera ture observations and by reference to the Comfort Chart (see Figs. 6, 8 and 9) or tables. The relation of winter and summer sensations of comfort to wet- and dry-bulb temperature at low air movement is shown in Fig. 6. This chart, published by an A.S.H.V.E. Technical Advisory Committee51, is based on research prior to 1932. Later studies by the A.S.H.V.E. Research Laboratory indicate somewhat higher temperatures for winter comfort, while Fig. 7 shows some variation in the requirements for comfort in summer cooled and air conditioned space. Relations between moisture content and various dry-bulb teinperatures to wet-bulb readings and effective temperatures are depicted in Fig. 8. Effective temperatures for various combinations of wet- and dry-bulb temperatures and air movement are given in Fig. 9. A long series of studies have been made to determine the optimum effective temperature for comfort of normal persons in both winter and summer air conditioned space, in different geographical regions and for : different age groups of men and women. A group of these studies52 was "A.S.H.V.E. Research Report No. 673--Determination of the Comfort Zone, by F. C. Houghten and C. P. Yaglou (A.S.H.V.E. Transactions, VoL 29, 1923, p. 361). A.S.H.V.E. Research Report No. 691--Cooling Effect on Human Beings by Various Air Velocities, by F. C. Houghten and C. P. Yaglou (A.S.H.V.E. Transactions, Vol. 30, 1924, p. 193). A.S.H.V.E. Research Report No. 717--Effective Temperature with Clothing, by C. P. Yaglou and W. E. Miller (A.S.H.V.E. Transactions, Vol, 31, 1925, p. 89). A.S.H.V.E. Research Report No. 755--Effective Temperature for Persons Lightly Clothed and Working in Still Air, by F. C. Houghten. W. W, Teague and W. E. Miller (A.S.H.V.E. Transactions, VoL 32, 1926. p. 315). "How to Use the Effective Temperature Index and Comfort Charts, by C. P. Yaglou, W. H. Carrier, Dr. E. V. Hill, F. C. Houghten and J. H. Walker (A.S.H.V.E. Transactions. Vol.' 38,1932, p. 420). "A.S.H.V.E. Research Report No. 1035--Comfort Standards for Summer Air Conditioning, by F. C. Houghten and Carl Gutberiet (A.S.H.V.E. Transactions. Vol. 42. 1936, p. 215). A.S.H.V.E. Research Report No. 1055--Cooling Requirements for Summer Comfort Air Conditioning, by F. C. Houghten, F. E. Giesecke, C. Tasker and Carl Gutberiet (A.S.H.V.E. Transactions, VoL 43,1937, p. 145). A.S.H.V.E. Research Report No. 1088--Summer Cooling Requirements of 275 Workers in an Air Conditioned Office, by A. B. Newton, F. C. Houghten, Carl Gutberiet and R. W. Guailey (A.S.H.V.E. Transactions, VoL 44,1938, p. 337). Cooling Requirements for Summer Comfort A& Conditioning in Toronto, by C. Tasker (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 549). A.S.H.V.E. Research Report No. 1127--Reactions of Office Workers to Air Conditioning in South Texas, by A. J. Rummel, F. E. Giesecke, W. H. Badgett and A. T. Moses (A.S.H.V.E. Transactions, Vol. 45, 1939. p. 459). A.S.H.V.E. Research Report No. 1136--Summer Cooling Requirements in Washington, D. C., ana Other Metropolitan Districts, by F. C. Houghten, Carl Gutberiet and Albert A. Rosenberg (A.S.H.V.E. Transactions, Vol. 45. 1939, p. 577). A.S.H.V.E. Research Report No. 1160--Reactions of 745 Clerks to Summer Air Conditioning, by W. J. McConnell and M. Spiegelman (A.S.H.V.E. Transactions, VoL 46,1940, p. 291), 59