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

• We propose an approach for facilitating the integration of personalized comfort preferences to HVAC operations.
• We propose and test a thermal preference scale.
• Several features of the scale improve consistency of the user provided information.
• The proposed preference scale outperforms an ASHRAE like five-point scale.
• Ambient temperature is the most influential factor on users' votes.

Thermal comfort is the main driving factor in determining heating, ventilation and air conditioning (HVAC) systems' 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 users' 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 users' 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 users' expectations and their votes. The results of the field study showed that the ambient temperature is the most effective factor on users' 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.