A thermal preference scale for personalized comfort profile identification via participatory sensing

Thermal comfort is the main driving factor in determining heating, ventilation and air conditioning (HVAC) systemsʹ operational settings. Current building management systems (BMS) operate according to conservatively defined and standardized settings. Many dynamic environmental and human related variables affect occupant thermal comfort in buildings, calling for flexibility in HVAC operations by integrating dynamic user preferences. This paper builds on the vision that a participatory sensing based approach could be used for integrating user thermal comfort preferences into the operational logic of HVAC systems on a real time and continuous basis. The paper emphasizes on participatory sensing requirements for improving human data acquisition by proposing a thermal comfort preference scale. Several guiding features, which could potentially improve the usersʹ expressions of thermal comfort preferences, were evaluated. Interface usability evaluation methods, including think aloud usability assessment studies and task execution surveys, were used in order to assess the proposed alternatives. Moreover, a field experiment was conducted to explore the driving factors, which affect usersʹ thermal preference vote, for determining HVAC control parameters. The results showed that the proposed sensation scale outperforms a five-level ASHRAE like scale and the addition of the guiding features helps increase the consistency between usersʹ expectations and their votes. The results of the field study showed that the ambient temperature is the most effective factor on usersʹ votes. Consequently, HVAC set points for temperature could be used as a control parameter for personalized thermal comfort without any need for retrofitting HVAC system components.