Pre-Retrofit Assessment of Thermal Comfort and Excess Moisture in Post-War Multi-Unit Residential Buildings in Toronto (ST-16-C029)

Energy retrofits provide an economically attractive solution to reduce the carbon footprint of existing buildings. However, indoor environmental quality and occupant comfort are often overlooked in the retrofit process. In this paper, we present the results of pre-retrofit monitoring of several multi-unit residential buildings in Toronto, Canada. The temperature, relative humidity and mean radiant temperature were measured in over 70 units across seven social housing buildings (built between 1960 and 1980) currently undergoing an energy retrofit process. Occupant thermal comfort was estimated using the Graphic Comfort Zone Method outlined in ASHRAE Standard 55-2013 and excess moisture was calculated as the vapour pressure excess during non-air conditioning periods. The major finding was that on average, the units were uncomfortable more than 70% of the time, with overheating being the main cause of discomfort. Location within a building (e.g., upper vs. lower floors) and building-specific effects showed little impact, although there was a weak seasonal effect with more overheating in the winter and spring. These findings are consistent with an occupant survey taken early in the project.  There was no consistent evidence of excess moisture, although this may be due to the observed overheating in the units. The results were used to inform the energy retrofit design process and are currently being monitored to ascertain how the retrofits affect occupant comfort in these buildings.