Thermal comfort approaches and building performance

Currently, the suitable indoor temperature is commonly defined according to the thermal comfort theory formulated by Fanger (1970). This approach bases the definition of thermal comfort on mere physics and completely neglects the social and psychological aspects of thermal perception. Moreover, its formulation is completely steady-state, determining a very narrow range of allowable temperatures throughout the year regardless of the outdoor conditions. An alternative approach to defining comfortable temperatures is the adaptive approach, which stems from the results of a wide range of field studies. It assumes that the thermal expectations of the users are linked to the outside climatic conditions on a variable basis. This chapter describes these two approaches and summarises the most relevant adaptive comfort indices. Furthermore, based on the different adaptive formulations, the comfortable temperature trends are derived and compared for two locations in Italy characterized by opposite climatic conditions. Finally, the possible implications on building thermal performance are analysed by means of a case study application.