Smart thermostats & high-rise housing

Completed doctoral research · University of Toronto

This one-year field study equipped 54 suites in two Toronto high-rise condominium buildings with smart thermostats and combined thermostat records, energy submetering and resident surveys. It examined comfort and over-conditioning, how residents programmed and overrode controls, whether occupancy-based and load-shifting strategies reduced HVAC runtime, and how reliably connected-thermostat data could support modelling.

Comfort was not only a thermostat problem

Nearly half of respondents reported discomfort during heating season and just over half during cooling season. Suites were also frequently over-conditioned, and the analysis pointed to central corridor ventilation as a likely contributor. Better suite controls therefore could not be considered separately from whole-building operation.

Smart controls helped—but building operation set the ceiling

Occupancy-based control reduced avoidable demand, but short in-suite HVAC runtimes limited measured savings. Load shifting moved cooling runtime out of peak hours in some suites, but the five-degree pre-cooling strategy prompted resident overrides and increased energy use and greenhouse-gas emissions in most tested scenarios.

Thermostat data need validation

Thermostat-reported runtime did not correspond one-to-one with equipment runtime at five-minute resolution. Agreement improved when data were aggregated hourly, although thermostats underreported runtime by about eight per cent on average, and no single prediction approach performed well for every suite.

Research team

Marianne Touchie (supervisor and principal investigator, University of Toronto)

Papers