Covering roofs and walls of buildings with vegetation is a good way of reducing greenhouse gas emissions. And these green roofs and walls make cities look nicer. Toronto’s central business district adopted a policy of establishing green roofs on around half of all city buildings in 2009. Research shows this could reduce maximum city temperatures by up to 5℃.
We spent the past 12 months analysing the case for more greenery on Australian city buildings, drawing on international comparisons. We’ve shown that a mandatory policy, coupled with incentives to encourage new and retrofitted green roofs and walls, will provide environmental, social and business benefits.
These include improved air quality, energy conservation and reductions in stormwater run-off from buildings, which would decrease flash flooding. Green roofs and walls also become new habitats for biodiversity and can be pleasant spaces for social interaction in dense urban areas.