Retrofitting for a Greener Future: Transforming Toronto’s Aging Buildings
- velesconstruction
- Jun 6
- 3 min read
As climate change accelerates, cities across Canada are intensifying efforts to reduce greenhouse gas (GHG) emissions. In the Greater Toronto Area (GTA), retrofitting older buildings for energy efficiency has emerged as a pivotal strategy. These initiatives are not only about lowering utility bills but are essential to achieving Toronto’s ambitious climate goals, including the target of net-zero emissions by 2040.
Buildings are the largest source of GHG emissions in Toronto, accounting for nearly 60% of total community-wide emissions. This significant contribution is primarily due to the extensive use of fossil fuels, especially natural gas, for heating and hot water in residential and commercial buildings. Retrofitting these structures is a cost-effective approach to significantly reduce emissions, enhance occupant comfort, and increase property values.
The Deep Retrofit Challenge
At the forefront of Toronto’s retrofit movement is the Deep Retrofit Challenge (DRC), a bold initiative launched in 2022 with $5 million in funding from Natural Resources Canada’s Zero Emission Buildings Program. The DRC supports comprehensive energy upgrades in 10 to 16 privately owned buildings, including multi-unit residential and commercial properties, aiming to demonstrate scalable pathways to low-carbon performance.
Each participating building is required to achieve:
A minimum 50% reduction in GHG emissions
A minimum 50% reduction in total energy use intensity (EUI)
A payback period of 20 years or less
To support these goals, the program offers grants covering up to 25% of eligible project costs, capped at $500,000 per building. Additional financial tools, such as the Energy Retrofit Loan and High-Rise Retrofit Improvement Support (Hi-RIS) program, are also available to assist building owners in funding their projects.
Progress and Impact
As of 2025, eight buildings have fully committed to the Deep Retrofit Challenge, with retrofit work expected to be completed by early 2025. These projects have undergone integrated design workshops and pre-retrofit energy modelling to ensure the effectiveness of the planned upgrades. Post-retrofit performance will be assessed over one year to determine actual energy savings, with comprehensive case studies to be published in 2026.
The retrofits funded through the Challenge are expected to result in approximately 1,750 tonnes of carbon dioxide equivalent (tCO₂e) per year in emissions reductions starting in 2025 when the retrofits are complete. These projects will serve as real-world examples to inspire broader industry adoption and inform future energy codes and policies.
Broader Climate Initiatives
Toronto's commitment to sustainability extends beyond the DRC. The city's TransformTO Net Zero Strategy outlines a comprehensive plan to reduce community-wide emissions by 50% by 2030 and achieve net-zero by 2040. However, recent data indicate that the current pace of emissions reductions is insufficient to meet interim targets. In 2022, Toronto's community-wide GHG emissions were 15.5 megatonnes (MT) of CO₂e, a 5% increase over the previous year, highlighting the need for accelerated action.
To address this, Toronto has implemented new measures, including the Energy and Water Reporting By-law, which requires owners of large buildings to report their energy and water use annually. This initiative aims to benchmark building performance, identify opportunities for improvement, and support the city's efforts to reduce GHG emissions from the building sector.
Looking Ahead
The Deep Retrofit Challenge represents a significant step toward transforming Toronto's building stock into a more sustainable and energy-efficient asset. By demonstrating replicable, cost-effective pathways to deep energy reductions, the DRC seeks to build market confidence and catalyze broader adoption of retrofit projects across the city.
As the program progresses, the City of Toronto plans to share updates on participating buildings and project outcomes, providing valuable insights for building owners and industry stakeholders interested in pursuing similar retrofit projects.
For more information on the Deep Retrofit Challenge and other sustainability initiatives, visit the City of Toronto’s Better Buildings Partnership page.
References
City of Toronto. (2023, January 18). City of Toronto launches Deep Retrofit Challenge to
accelerate energy efficiency in existing buildings to help meet goal of net zero emissions.
City of Toronto. (2024). Deep Retrofit Challenge. Better Buildings Partnership.
buildings/better-buildings-partnership/deep-retrofit-challenge/
City of Toronto. (2025, January). Deep Retrofit Challenge Toolkit. https://www.toronto.ca/wp-
Natural Resources Canada. (2024). Canada Greener Homes Initiative. https://natural-
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