In recent years, cities across Ontario have experienced major weather events, where flooding caused damage to both public and private property. As more extreme weather patterns occur, cities like Mississauga, Ont., are looking at innovative and adaptive drainage solutions to help with these challenges.
That’s where the smart blue roof comes in.
The smart blue roof was recently installed at Credit Valley Conservation’s (CVC) head office. It’s Canada’s first smart blue roof system that is compliant with the Canadian Standards Association’s rainwater harvesting systems standard (CSA B805-18).
What is a blue roof?
According to the CVC, a smart blue roof is an adaptive stormwater management technology that uses programmable logic control technology and an extensive sensor network to determine how captured rainwater is best used.
The technology can decide, based on predetermined limits, to hold the water until it evaporates, providing cooling benefits to the building, or to drain the rainwater into a harvesting tank where it can be treated and reused for non-potable purposes. It also may decide to release some of the water slowly back into the city’s stormwater system during dry-weather conditions.
Used with permission – Smart Blue Roof. (CVC/City of Mississauga). https://cvc.ca/project/smart-blue-roof/
The City of Mississauga has become the first city in Canada to participate in the implementation of a CSA-compliant smart blue roof. (City of Mississauga and Credit Valley Conservation)
If the storage capacity of the roof is exceeded, then water is safely discharged through one of two overflow routes. The storage capacity of the roof was determined with a structural load assessment.
A blue roof is designed to capture and detain rainwater on a low-slope roof surface–therefore, this technology is not an option for the average home that has a sloped roof.
Used with permission: Graphic showing how the smart blue roof works. (City of Mississauga and Credit Valley Conservation)
Control valve overview. (City of Mississauga and Credit Valley Conservation)
Challenges to overcome
James Cowan, an engineering specialist with CVC, explains that the challenges associated with this roof include:
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Keeping up with building codes and regulations.
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The technology is so new that there aren’t many consultants and contractors in Canada with the expertise to build a blue roof.
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The smart blue roof cannot be used in the winter because if the water freezes, it may cause performance and safety concerns.
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Flooding can cause costly damage to homes, businesses, and infrastructure. It can also disrupt essential services and utilities like transit and electricity. Ongoing flooding can also cause erosion, harm local ecosystems, and cause debris and pollutants to contaminate our drinking water source – Lake Ontario. The hope is to use this smart blue roof technology to mitigate costly flood damage.
This technology is not yet accessible to the public, but the CVC, in collaboration with the City of Mississauga, continues to assess the real-world performance of the system in order to understand how to scale this technology in the local industrial, commercial, and institutional sectors and in communities across Canada.
Used with Permission: Smart blue roof – Project construction began in the Summer of 2022. The construction project team consisted of CVC, Enviro-Stewards Inc., Interpump Ltd., Firenza Plumbing and Heating Ltd., WSP Canada, PAC Building Group, and TRIO Roofing Systems Inc.
Project construction began in the Summer of 2022. The construction project team consisted of CVC, Enviro-Stewards Inc., Interpump Ltd., Firenza Plumbing and Heating Ltd., WSP Canada, PAC Building Group, and TRIO Roofing Systems Inc. (City of Mississauga and Credit Valley Conservation)
With its early success, the project won a 2025 Clean50 Top Project Award, showing its potential to inspire similar initiatives across Peel Region and Canada, as many municipalities are facing increased rainfall due to extreme weather events.
To learn more, visit cvc.ca/project/smart-blue-roof.