Environment International, Vol. 17, pp. 205-209, 1991 0160-4120/91 $3.00 + .00 Printed in the U.S.A. All rights reserved. Copyright © 1991 PergamonPress plc CLOTHING: AN ESSENTIAL INDIVIDUAL ADJUSTMENT FACTOR FOR OBTAINING GENERAL THERMAL COMFORT G. Alfano and F. R. d'Ambrosio Dipartimento di EnergetJca TErmofluidodinamica applicata e Condizionamenti ambientali (DETEC). Universit~ di Napoli + Federico II, Naples, Italy E18909-232M (Received15 June 1989; accepted5 October 1990) In air conditioned buildings where thermal conditions comply with existing building codes and standards, many people often complain of unpleasant thermal sensations. These complaints may often be caused by differences in the occupants' activity level and the fact that people are not alike and may prefer different thermal conditions. In this paper, the important role played by clothing in the attainment of thermal comfort is stressed and it is shown how the clothing may be used to compensate for different activities and personal differences. This phenomenon is analyzed by assessing the sensitivity of the Predicted Percentage of Dissatisfied (PPD) index to the subject's activity and to the thermal insulation of the clothes they wear. INTRODUCTION Those who have experience in the operation of air-conditioning systems know that, even though they may be well designed and constructed, they are often the cause of complaints. Especially when win- dows cannot be opened and if the working en- vironment is large and does not allow differentiated localized adjustments. Even if the results of measure- ments indicate that environmental parameters are con- stant over time, uniform and equal to the design values, often there is a large number of dissatisfied occupants. This phenomenon will be analyzed here in the light of the existing and well-established body of theory. It is then suggested that this phenomenon has a much wider scope than has been envisaged by the theory itself. As is well known, by the Fanger Theory (Fanger 1970), it is possible to evaluate the Predicted Mean Vote (PMV) index which predicts the mean value of the votes of a large group of persons on a seven-point thermal sensation scale, with PMV = 0 for neutral, or comfort condition. The PMV index can be deter- mined when the metabolic rate and the clothing thermal insulation are estimated and the following environmental parameters are measured: air tempe- rature, mean radiant temperature, relative air velocity and relative humidity. By the Fanger Theory, when the PMV value has been determined, it is also possible to find the Predicted Percentage of Dissatisfied (PPD) index that establishes a quantitative prediction of the number of thermally dissatisfied persons. In the S.I. system the metabolic rate and the cloth- ing thermal insulation are measured respectively in W/m 2 and in °C-m2/W; but often they are measured also, respectively, in met-unit (1 met = 58.15 W/m 2) and clo-unit (1 clo = 0.155°C.m2/W) which will be used in this paper. 205