Source: Financial Post

Toronto has a high concentration of multi-unit residential buildings (MURBs) with the bulk that were built during the 1960s and 1970s. Today, these buildings are mostly owned by social housing and around 29 per cent of all rental units in Toronto are social housing MURBs. Current issues with MURBs are linked to energy usage not being considered when these buildings were built and also not being well maintained. Toronto is now In the midst of a second boom for MURBs but there is limited data on how the newer MURBs are performing.

At the SOCAAR Seminar on March 1st, Dr. Marianne Touchie, Assistant Professor at the University of Toronto’s Departments of Civil Engineering and Mechanical Engineering spoke about why energy retrofits of MURBs should take a comprehensive and not piecemeal approach.

The energy use in MURBs is highly variable and is linked to how occupants are interacting in the building. In comparison, the energy use in commercial buildings is more closely related to the building characteristics. The energy use in typical Canadian MURBs is mostly spent on space heating and water heating, over 50 per cent and over 25 per cent respectively. This energy is mostly provided by burning natural gas which produces greenhouse gas emissions. In addition to cost savings, energy retrofits could also help meet Canada’s greenhouse gas emission targets.

Decisions on making energy retrofits to MURB are often driven by equipment failure, incentive programs or the need to reduce operating expenses. Such energy retrofits typically have quick payback periods that are under one year, targeting lighting and water fixtures like toilets or shower heads. But this piecemeal approach of making energy retrofits takes longer and is more expensive than a more comprehensive approach. A comprehensive approach to energy retrofits reduces the vulnerability to changing utility prices.

Dr. Touchie presented an approach to comprehensive energy retrofits by investigating the effects of uncontrolled air leakage from the exterior and chronic over- or under-heating in different parts of the buildings. She also shared how changes in energy use can affect occupant comfort and health by directly impacting the active systems that provide ventilation and space conditioning. The next phase of her research is to investigate the energy benefits of using smart thermostats in MURBs to study window air leakage issues. Ultimately, the goal is to balance occupant comfort and energy usage.