Toronto’s skyline is getting greener, thanks to a bylaw that mandates green roofs on many new buildings. But what exactly is this bylaw, and why is it such a big deal?
Implemented in 2009, Toronto’s Green Roof Bylaw was the first of its kind in North America. It requires a percentage of rooftop space on new buildings exceeding 2,000 square meters to be dedicated to green roofs. The amount of green roof required also depends on the building type:
Commercial, institutional, and residential developments require a green roof covering 20% to 60% of the available roof space, depending on the building size.
Industrial buildings have a slightly different requirement. They must either have a green roof covering 10% of the available roof space or 2,000 square meters, or install cool roofing materials across the entire available roof space. Cool roofing materials reflect sunlight and heat, helping to reduce energy consumption.
So, why the push for green roofs? Toronto, like many urban centres, faces challenges like flooding due to overwhelmed storm drains and rising temperatures from sprawling concrete areas. Green roofs act as natural sponges, absorbing rainwater and releasing it slowly, reducing pressure on drainage systems. The vegetation also helps cool buildings by providing shade and insulation, lowering energy consumption.
However, a green roof isn’t a “set it and forget it” solution. Ongoing maintenance is crucial for the health of the plants and the overall integrity of the roof. Neglected green roofs can become riddled with weeds and other invasive species which can cause drainage issues and even compromise the waterproofing membrane. Part of the green roof bylaw (By-law No. 583-2009 492-N) requires monthly maintenance visits on every green roof to ensure operational efficiency. Failure to comply with the bylaw and maintain the green roof can result in fines for building owners.
Looking ahead, Toronto’s Green Roof Bylaw serves as a springboard for stricter sustainability measures in construction. Many experts believe the bylaw’s success will pave the way for even more progressive regulations. We might see a future where green roofs become mandatory for all new buildings, or where the bylaw expands to include other sustainable features like solar panels or rainwater harvesting systems.