Green roof technology and its proponents...

Green roofs are fascinating. They are starting to be a good source of discussion in the environmental policy sphere. They are starting to take off in North American cities and have been popular in Europe for decades. Green roofs are mainly developed for storm water management. A lot of the roof tops on buildings found within urban centers have impervious surfaces. When precipitation falls on the roofs, it runs off into the sewer system on the roads below. When rain falls in heavy amounts, it gradually degrades the roofs and building infrastructure making it very expensive to replace over time. Local vegetation, reducing the urban heat island effect and managing storm water are all notable features of a green roof.

With more gardens and vegetation on roof tops, more rainwater is retained. Some green roofs in British Columbia have little wells on the roofs that direct water into an underground aquifer. The water is trapped and saved for watering vegetation in droughts or dry seasons. Local vegetation provides for the local market providing fresh and organic alternatives. Local vegetation or quite simply growing food locally has numerous benefits and will be critical for our future. Cities like Hong Kong are really progressive with green roof technology. 50% of Hong Kong's vegetation is grown within the city limits on roof tops and high-rises.

Other cities like Berlin, Portland and even Toronto have been rapidly bringing about these urban sustainability solutions. Why is this even happening? Because urban areas often lack green space and biodiversity and are trying to think of innovative ways to integrate urban infrastructure with green space; and therefore green roofs are becoming viable options. 50% of German cities offer subsidies to building owners for installing green roof systems. For example, let's look at Berlin. Berlin’s subsidy program reimburses residents 50% for green roof construction costs and in 1997, resulted in 63,500 m² of green roofs built across the city. This has improved storm water management tremendously and has provided citizens with more local food options. One thing Toronto is doing is running pilot projects to see how viable they are. Toronto’s Green Roof Incentive Pilot program offers a grant of $10m² to eligible green roofs. Developers are finding this appealing because it will only save them on infrastructure costs in the future.

Key Message: Green roofs are an urban sustainability solution, funding from the local government to install them is a good first step. Providing market-based incentives, running pilot projects and involving the public in the process are the essential first steps. Regulation or a green roof bylaw, should only be considered if the first steps have not worked.