Document B83Bkz44oakJ20Ye65GZ7p2Vk

124 CHAPTER 6 1957 Guide nearly horizontal. It therefore appears that the slope of the ET lines may vary, depending upon the rate of work being performed. ^Fig. 10 shows the A.S.H.A.E. Comfort Chart22 as published since 1950. l ne areas and arrows indicating the summer and winter comfort zones on the previous, charts have been removed. The summer comfort zone was removed because it extended to temperatures where too large a percentage of the people would be uncomfortable. The winter comfort zone was re moved for the same reason, and because of inadequate data in later studies. Physiological Principles 125 The distribution curve, showing the percent of people feeling comfortable at various effective temperatures in summer, indicates that a maximum of 98 percent of the people were comfortable at 71 ET. The study was conducted with relative humidities between 30 and 70 percent. The distribution curve shown on the previously used chart, showing the percent of people feeling comfortable at various effective temperatures in the winter, was based on research prior to 1932. This curve indicated that at 66 ET a maximum number of people were comfortable. Later studies21 by the A.S.H.A.E. Research Laboratory indicated that a maxi mum of 97.7 percent of the people were comfortable at 68 ET, and this finding has been confirmed by current practice.24 However, adequate data from the later studies were available only for the ET range of 65 to 69, Fig. 9. Effective Temperature Chart Showing Normal Scale of Effective Temperature, Applicable to Inhabitants of the United States Undeb Following Conditions: A. Clothing: Customary indoor clothing. B. Activity: Sedentary or light muscular work. C. Heating Mcihodt: Convection type, warm air, direct steam or hot water radiators, plenum systems. as presented in Fig. 10. The studies should be extended to cover a wider range. The lighter weight clothing, probably worn in the later studies, accounts for the higher desirable ET. Radiation from occupants to room surfaces, and between the occupants, has an important bearing on the feeling of warmth, and may alter to some