Unlocking thermal comfort in transitional spaces: A field study in three Italian shopping centres

Shopping centres are commonly laid out as small individual stores connected by transitional spaces. Setpoint temperatures used to control transitional spaces are normally the same as in traditional indoor environments despite substantial differences in use, time of permanence and users' needs. Currently, there are no comfort guidelines for transitional spaces and the literature lacks relevant studies on the topic. There is an untapped potential for energy savings and improved indoor environmental quality. The main objective of this work is to evaluate the suitability of Fanger's comfort model and adaptive comfort model for transitional spaces. We assessed users' thermal perception and potential impacting factors in three Italian shopping centres. 724 customers were interviewed on their thermal comfort, thermal sensation, thermal preference, and clothing level while experiencing the transitional space. In addition, the thermal environment at the interview locations (dry-bulb temperature, globe temperature, relative humidity, and air speed at different levels) and the outdoor temperature were monitored. The study demonstrated that Fanger's model and the adaptive comfort model are not suitable for transitional spaces. Customers were inclined to adapt to a much wider range of indoor environmental conditions. An operative temperature of up to 27.5 °C was still deemed comfortable by more than 80% of the customers. These results unlock a large potential for energy savings and pave the way for passive solutions such as natural ventilation.