Toronto introduced 10 years ago that every new building with a ground area over 2,000 m² must be equipped with a green roof.

Ten years have passed since, in 2009, the Municipality of Toronto enacted a local bylaw requiring that the roof of any new building with a ground area exceeding 2,000 m² within the metropolitan area be equipped with a green roof.

The objectives set by this bylaw at the time were as follows:

• reduction of the Urban Heat Island effect
• stormwater management
• reduction of electricity consumption
• creation of urban green spaces
• biodiversity and urban habitat
• improvement of air quality
• new jobs in the green sector

The bylaw was prepared through a series of preliminary actions in the preceding years. A Green Roof Strategy was developed, which mandated the inclusion of green roofs in the approval process for new projects. In 2007 alone, 14 green roof systems were implemented as a result of this strategy. Additionally, it was required that the Municipality’s own buildings install green roofs on 50% of suitable roof areas. Therefore, the 2009 bylaw and its entry into force on January 31, 2010, was not a surprise for stakeholders in the field.

The mandatory requirements are flexible, ranging from a minimum of 20% of the built area for buildings between 2,000 and 4,999 m², up to 60% for buildings with a ground area exceeding 20,000 m². Larger projects are considered better able to absorb the additional costs required for green installations within their budgets.

After 10 years of implementation, conclusions and figures can be drawn that reflect the value of the measure taken in 2009:

• 620 green roof projects were completed, totaling 500,000 m² of intensive and extensive systems
• 1,618 new jobs were created

Annual benefits:

• 220 million liters of stormwater were managed annually
• 225 tons of carbon were sequestered from the atmosphere
• 3.2 million kWh of electricity saved in buildings with green roofs
• 1.6 million kWh of energy saved in surrounding buildings due to reduction of the Urban Heat Island effect

It can be concluded that Toronto’s local bylaw has generated measurable benefits at a relatively low cost compared to the total investment in the real estate development sector.

Source: Living Architecture Monitor