When the Chinese describe the weather, they do so in terms of the number of suits required for thermal comfort. They speak of a "one-suit" day when the weather is moderate, a "two-suit" day when it is a little cooler and a "twelve-suit" day when it is bitter cold. 1,z To treat this relationship between thermal environment and clothing more objectively, a modem interpretation might state that in order to maintain a condition of heat balance in the human body which would result in a thermal sensation of "comfortable" as the temperature decreases, more clothing is required. Conversely, as the temperature increases less clothing is required for man to be comfortable while engaged on any given level of activity.

To carry this axiom from the realm of the subjective into the laboratory, Gagge, Burton, and Bazett3 proposed the "clo" unit as a measure to quantify the insulative value of various clothing ensembles. Defined, one clo is the "the amount of insulation necessary to maintain comfort and mean skin temp of 92 F in a room at 70 F with air movement not over 10 ft.imin, humidity not over 50% with a metabolism of 50 calories per square meter per hour" (resting condition)4 (p. 445).

Careful study of this definition will reveal that the cIo unit is arbitrary. Nevertheless, it has been standardized with empirical evidence and has been assigned to various clothing . ensembles by means of electrically-heated copper manikins. Winslow and Herrington2 state that a resting nude male (zero clothing) is comfortable at 86 F when the humidity is moderate and the air movement is low. However, when one clo of insulation is worn, the air temp must be reduced to 70 F to obtain the same degree of comfort. Fanger5 has determined the relative effects of clothing and temp on thermal comfort by means of a comfort equation and it agrees favorably with the data in the new ASHRAE Comfort Chart6,7. New synthetic materials and styles of dress and fashion have dictated the need for additional information on the relative effects of clothing 'alld temp on sedentary comfort and are the impetus for the present study. Its purpose is to determine the effects of various clothing ensembles on the thermal sensation on sedentary human subjects exposed to moderate temp.