Almost 30 per cent of Toronto’s multi-unit residential building (MURBs) stock is social housing and many of those buildings are more than 50 years old and ripe for retrofit.
The problem is not small.
Marianne Touchie, an assistant professor at the University of Toronto (U of T), says that the Toronto Community Housing Corporation faced more than $2.5 billion in a backlog of repairs and maintenance in 2015.
Touchie is conducting a joint field study examining overheated buildings and related performance problems for more than 70 apartments in seven buildings — low, medium and highrise — owned by social housing providers in Ontario.
To conclude next year, the study is through U of T's Faculty of Applied Science and Engineering in collaboration with The Atmospheric Fund, an agency that looks at solutions to greenhouse gas and air pollution in urban settings in southern Ontario.
Touchie, who gave a presentation on the study's findings to date at the Learning About Building Event seminar series held at RDH Building Science Inc.'s offices in Waterloo, Ont. recently, told the audience the average temperature measured in summer in the buildings was over 27 C. On "extreme heat" days 80 per cent of the units were more than 30 C.
Overheating "is a huge problem and it is only going to get worse" because of global warming, said Touchie.
While active cooling improvements are important in building retrofits, any future retrofits should take into account passive cooling measures such as energy efficient windows with fall protection grates, window films and shading, she said.
Many of the highrises in the study have double loaded corridors, preventing cooling by cross ventilation, and windows — often single pane — have small openings, exacerbating the heat problem. Some units have window air conditioners but central air conditioning is rare.
Touchie said Toronto Public Health has predicted that heat related deaths will double over the next 30 years.
"It is particularly a problem in lower income housing because they don't always have access to active cooling," she explained.
Touchie told the audience while there have been many studies on occupant comfort in commercial buildings, the same can't be said for MURBs. That must change as aging residential building stock comes up for retrofits.
The study team is supplementing monitoring data of a number of units with a residents' survey. Residents were polled on their comfort perceptions related not just to temperature but indoor air quality.
"There is a lot of complexity in looking at thermal comfort," she said. "A lot of it has to do with occupant perception. It is not just as simple as looking at temperature."
Touchie, who has studied MURBs for the past decade, said that U.S. studies indicate that social housing uses 40 per cent more energy than private housing.