Comparative usability study between two prototype commercial building thermostat interfaces

Abstract

The functionality of commercial building thermostats is often not well understood by occupants. This can lead to users feeling discontent and/or frustrated and may contribute to inefficient thermostat operation and related energy outcomes. Thus, the usability of such thermostats is critical to elicit effective operation from users. However, usability principles (e.g., intuitive colors, icon standardization) are rarely prioritized in thermostat interfaces. This study investigates the relationship between usability principles and thermostat interfaces using a comparative study. Two prototype commercial building thermostat interfaces were examined: one that resembles current devices (control thermostat) and one that incorporates usability principles (experimental thermostat). Eighty-five participants participated in an online survey and user test, during which they were asked to perform various tasks on both interfaces. Participants rated various aspects of each interface (e.g., the overall intuitiveness, a specific feature). Human-interface interactions were recorded by Useberry, an interface prototyping software tool. The success rate for usability tasks was largely the same between control and experimental thermostats; however, most participants (78%) preferred the additional features offered by the experimental interface. This paper serves to both explore novel thermostat features that aim to improve usability as well as introducing rapid prototyping as a solution to improve commercial building thermostat usability.