Document 8RbKgdbJQXobzGj7gdG50gdem

American Society of Heating and Ventilating Engineers Guide, 1935 I" Note.--Both summer and winter comfort zones apply to inhabitants of the United States only. Applica tion of winter comfort line is further limited to rooms heated by central station systems of the convection type. The line does not apply to rooms heated by radiant methods; Application of summer comfort line is limited to homes, offices and the like, where the occupants become fiilfy adapted to the artificial air con ditions. The line does not apply to theaters, department stores, and the like where the exposure is less than 3 hours. mately the same value in July, August'and September, and although the average monthly temperature did not vary much, the prevailing outdoor temperature ranged from 70 F to 99.5 F. A decrease in the optimum temperature became apparent only when the prevailing outdoor tempera ture fell to 66 F, which is below the customary room temperature in'the United.States for summer.arid winter. 4 Young men as a general rule prefer conditions in the cool region of the comfort zone, arid womeri rind older ..people- in the warm region of: the 44 ------ Chapter 2--Ventilation and Air Conditioning Standards fort zone. Crowding the experimental chamber lowered the optimum Cffprtive temperature from 70.8 deg when the gross floor area per occupant e" s 44 sq ft and the air space 380 cu ft, to 69.4 deg when the floor area was reduced to 14 sq ft and the air space to 120 cu ft per occupant. In the comfort zone experiments of the A.S.H.V.E. Research Labora tory the relative humidity was varied between the limits of 30 and 70 per ent approximately, but the most comfortable range has not been deter mined In similar experirrients at the Harvard School of Public Health, a elative humidity of 70 per cent was found to be somewhat humid in winter, bv about half of the subjects who were stripped to the waist, even when the dry-bulb temperature was 70 F or less. In summer, a relative humi dity of 30 per cent was pronounced as a little too dry by about a third of the subjects wearing warm-weather clothing. So long as the temperature was kept within proper limits, the majority of the subjects were unable to detect sensations of humidity (i.e., too high, too low, or medium) when the relative humidity was between 30 and 60 per cent. This is in accord with studies by HowelF, Miura24 and others. Dry air produces an excessive loss of moisture from the skin and respira tory tract. Owing to the cooling effect of evaporation, higher tempera tures are necessary, and this conditiori leads to discomfort and lassitude. Moist air, on the other hand, interferes with' the normal evaporation of moisture from the skin, and again may cause a feeling of oppression and lassitude, especially when the temperature is also high. Just what the optimum range of humidity is, is a matter of conjecture. There seems to exist a general opinion, supported by some experimental and statistical data, that warm, dry air is less pleasant thari air of a moderate humidity, and that it dries up the mucous membranes in such a way as to increase susceptibility to colds and other respiratory dis orders25, 26, 27. For the premature infant, a high relative humidity of about 65 per cent is demonstrably beneficial to health and growth28, and according to Huntington29, this seems to be the case for adults also. All of these studies indicate that the optimum humidity must always be considered in combination with temperature. Until more exact information's secured, it would be desirable to restrict the comfort zones to the range, of relative humidity employed in the comfort zone experiments, namely, 30 to 70 per cent. Relative humidities below 30 per cent may prove satisfactory from the standpoint of comfort, so long as extremely low humidities are avoided. From the standpoint of health, however, the consensus seems to favor a relative humidity between "Humidity and Comfort, by W. H. Howell (The Science Press, April, 1931). "Effect of Variation in Relative Humidity upon Skin Temperature and-Sense of Comfort, by U. Miura. (American Journal of Hygiene, Vol.13, 1931. p. 432). . '. "Reactions of the Nasal Cavity and Post-Nasal Space to Chilling of the Body Surface, by Mudd, Stuart, et a! (Journal Experimental Medicine, 1921, Vol. 34, p. li). "Reactions of the Nasal Cavity and Post-Nasal Space to Chilling of the Body Surfaces, by A. Goldman, et al and Concurrent Study of Bacteriology of Nose and Throat (Journal Infectious Diseases, 1921, Vol. 29, p- 151). "The Etiology of Acute Inflammations of the Nose, Pharynx and Tonsils, by Mudd, Stuart, et al (Am. Otol., Rhinol., and Laryngol., 1921). "Application of Air Conditioning to Premature Nurseries in Hospitals. by'C. P. Yaglou, Philip Drinker and K. D. Blackfan (A.S.H.V.E. Transactions. Vol. 36, 1930). "Weather and Health, by Ellsworth Huntington {Bulletin of the National Research Council No. 75. The National Academy of Stience, Washington, D. C;, 1930). 45