Green Roof Retrofits for Canadian Climate Resilience

Halton Region in Ontario, Canada, faces growing climate pressures, including intense storms, frequent flooding, and rising temperatures due to the urban heat island effect. Traditional infrastructure is not designed to manage these compounding risks.

A new policy brief titled "Bloom Above: Green Roof Retrofits" outlines a practical solution: converting existing rooftops into green roofs to strengthen climate resilience, reduce urban temperatures, and improve stormwater management.

Green roofs (vegetated layers installed on top of conventional rooftops) are proven to capture up to 65% of stormwater runoff, lower rooftop temperatures by 2 to 3 °C, extend roof lifespan, and increase energy efficiency. The brief highlights successful precedents in Toronto, where a mandatory Green Roof Bylaw has led to over 500,000 m² of vegetated roofing with measurable environmental and economic benefits.

The research proposes launching a municipal pilot project at Allendale Long-Term Care Home to evaluate feasibility, cost, and performance. Pilot data would inform broader regional policies and provide a replicable model for retrofitting other municipal, commercial, and residential buildings. This aligns with Halton Region’s Net Zero by 2045 climate goals and offers benefits that extend beyond infrastructure, such as improved biodiversity and positive mental health outcomes for residents.

Recommendations

1. Pilot Retrofit Program: Begin with a retrofit of Allendale Long-Term Care Home to collect data and assess benefits.

2. Incentive-Based Strategy: Offer tax rebates or credits to encourage commercial and residential adoption.

3. Mandatory Green Roof By-law: Require green roof coverage for new developments and major renovations.

4. Funding and Partnerships: Leverage programs like the Federation of Canadian Municipalities’ Green Municipal Fund to support implementation.

If adopted, these measures would reduce flood risks, lower energy costs, and advance climate goals, while positioning Halton as a leader in sustainable infrastructure.

Lark Scientific’s Role

Lark Scientific supported this research as part of its collaboration with the University of Waterloo’s EWEAL program, providing technical expertise and resources to help bridge academic insights with practical municipal applications. By contributing to evidence-based environmental solutions like green roof retrofits, Lark Scientific is helping accelerate climate adaptation strategies in communities across Canada.