Communicating HVAC Operation Through a Thermostat Interface: An In-Situ Implementation to Improve Perceived Control and Thermal Comfort in Offices

It is well understood that the ability to control the thermal environment through a thermostat interface can increase thermal comfort and productivity in offices.Less is understood about how the usability of thermostats, and more broadly the usability of building control systems, play a role in realizing these benefits.The field of human factors offers numerous techniques to design, test, and analyze interfaces; however, very few examples exist where these techniques were applied to thermostats.This thesis contributes to understanding how thermostat interfaces and the operation of the heating, ventilating, and air-conditioning (HVAC) control systems can affect occupant's perceived control in offices.The research was carried out in three phases across two heating seasons on 25 academic offices of an institutional building in Ottawa, Canada.Phase 1 applied an analysis of building control logic, building automation system (BAS) sensor data, and thermostat interactions, combined with a survey to identify barriers to usability in the offices.The surveys indicated a low sense of perceived control among participants.Three primary usability issues were identified: (1) setpoint regulation was contextual and was affected particularly by neighbouring offices due to the zoning employed in the building, (2) response times to setpoint adjustments were slow and highly variant, and (3) control was removed from office occupants during scheduled setbacks, and this was not communicated to office users.In Phase 2, features were developed to address these issues and were designed to be implemented into the existing thermostats of the building.The features included displaying (1) HVAC operational information (e.g., heating), (2) a time-to-temperature estimate, and (3) when scheduled setbacks were in effect.These features were implemented in all 25 offices.iii Phase 3 aimed to measure the operation and gather feedback about the implemented features.The feedback indicated that participants found value in the modifications to the thermostats and highlighted a need to include usability early in the design processes of the control system.In one instance, offering transparency to the system operation had an adverse effect, perhaps because the system was not designed to provide the level of individual control the participant expected.While this thesis focuses on a single institutional building, it is expected that the issues found in this building are widespread.The thermostats in this building did not meet fundamental recommendations of usability found in the human factors literature.This thesis represents the first real-world implementation in an office building of a thermostat with the features developed.The identified issues, development of the features, and feedback are documented to inform future iterations of this design.I first wish to acknowledge that this research was conducted at Carleton University, which is located on the traditional and unceded territory of the Algonquin Anishnaabeg People.This academic institution operates on stolen land abiding by the laws of an illegal colonial power that continues to occupy Indigenous lands while benefiting from the historical and the ongoing practices of genocide that perpetuate the oppression of Indigenous Peoples across Canada.As a graduate student of settler descent, I have conducted my research on this land for the benefit of my academic career.I wish to offer my recognition of, and gratitude for, the Indigenous lands on which I live and work, and the communities who still occupy the territory and continue to defend their rights as the traditional custodians of this land.The academic and professional engineering communities for which this research contributes to are currently facing critique due to their longstanding under-representation of First Nations, Inuit, and Métis.This issue is of critical importance, as all peoples should have the right to design, build, certify, operate, and control the infrastructure they depend on.During my work on this project, I was unable to identify ways in which my research intersected with these issues; however, as engineers, we often claim objectivity and apoliticism while failing to address how the practices within our fields enforce colonial values.In my career going forward, I plan to seek advisement and expand my ability to recognize how colonial ideologies are influencing my work.v I would like to acknowledge the efforts of Professor Liam O'Brien and Professor Chantal Trudel.Without their guidance and support, this project would not have been possible.Their mentorship has allowed me to perform and showcase my research, and I credit their kindness and encouragement for making this research a rewarding and enjoyable experience.I am thankful for the

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