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.