Toronto’s greenroofs can have a sizeable impact on the air quality in the city. Green roofs are like building a park over your entire city – or at the very least it would have similar impacts on air quality.

Using AutoCASE, I’ve calculated the amount Carbon Dioxide (CO₂) and other Criteria Air Contaminants (CACs) sequestered by Toronto’s planned and completed green roofs. The following map portrays all of Toronto’s green roof permit applications (all from City of Toronto’s Open Data Portal) – separated into four categories:

1. The green roof is complete and the permit is closed
2. The green roof permit has been issued but the permit is not yet closed
3. The green roof permit is some state of review.
4. The green roof permit application has been denied.

Clicking on a building will give you a summary. For example:

Address: 24 Howard St Toronto, Ontario, Canada
Permit Type: New Building
Status: Examiner’s Notice Sent
Structure: Apartment Building
Green Roof Area: 236.76M²
Annual CO₂ Sequestered: 0.33 tonnes
Annual Other Air Pollutants Sequestered 3,078 grams

AutoCASE can also calculate the flooding, stormwater management and heat island reduction benefits of green roofs. And in AutoCASE apart from area you can refine the analysis if you know whether the roof is New/Existing; Depth of Coverage Materials; Percent Empty Space in Coverage Material; Extensive/Intensive; Number of Trees Planted; Tree Diameter at Breast Height; Trees Average Expected Lifespan; Trees Maximum Lifespan; Number of Shrubs Planted; Shrubs Average Expected Lifespan; Shrubs Maximum Lifespan

Most of Toronto’s green roof applications are in progress, for one reason or another. The following table breaks down each one by permit category:

While the city has been issuing some permits, the amount currently backlogged is considerably large. For instance, reducing the total CO₂ by 395 tonnes is equivalent to driving 3,000,000 less km per year. Green roofs are great for cities and our health, and we should do what we can to make them more accessible.