HVAC systems testing and check: a simplified model to predict thermal comfort conditions in moderate environments

Abstract: A simplified approach to thermal comfort was developed in Seventies by Rohles, who found a correlation between PMV, air temperature and relative humidity, easily sampled in the environment (for sedentary activity and clothing thermal insulation < 0.5 clo). In the present paper an improvement of the Rohles model was tried, in order to generalize results in a wider range of clothing thermal insulation (Icl = 0 - 1.65 clo). Instrumental and questionnaire data available from wide experimental campaigns carried out by the Authors in classrooms and open space offices were used to implement a simplified model for the PMV calculation based only on air temperature an relative humidity measurement. Instrumental data were implemented in a new model by means of a function PMV = PMV(T, RH) and diagrams PMV versus temperature, for different values of relative humidity, were traced. A total number of 9 equations and diagrams was obtained (for Male, Female and Both, and for three ranges of Icl). The standard deviation between measured and calculated data was also evaluated and a mean error on PMV of ±0.22 was found. Questionnaire results were elaborated in the same way, but no good results were obtained, therefore an approach with Neural Network could be tried in the future.