The SPOT* Personal Thermal Comfort System

Conventional centralized HVAC systems cannot provide office workers with personalized thermal comfort because workers in a single zone share a common air handling unit and thus a single air temperature. Moreover, they heat or cool an entire zone even if a single worker is present, which can waste energy. Both drawbacks are addressed by Personal Environmental Control (PEC) systems that modify the thermal envelope around a worker's body to provide personalized comfort. However, most PEC systems are both expensive and difficult to deploy, making them unsuitable for large-scale deployment. In contrast, we present the design and implementation of the SPOT* PEC system that is carefully designed for rapid and scalable deployment. Intuitive web-based interfaces for user controls allow SPOT* to be installed in only about 15 minutes, including user training. It is also low-cost because it uses the fewest possible sensors and a lightweight compute engine that can optionally be located in the cloud. We present the detailed design of the SPOT* system and results from a cumulative 58,000 hours of operation in 15 offices. We find that in our deployment SPOT* reduced the average absolute discomfort experienced by a typical user by similar to 67% compared to the same HVAC system in the absence of SPOT*.