What is the problem?
Most of the roofs in the world’s cities and built-up environments are dark in colour and consist of nothing other than building materials. They are totally exposed to the weather. On cold days roofs are cold, on hot days roofs can get extra hot, reaching temperatures up to 30°C hotter than the air. This additional warming contributes to an effect known as the Urban Island Effect, where it is significantly hotter in cities then out.
Traditional roofing makes the contrast between the outside and the inside temperatures stark, meaning it takes a lot of energy to cool and warm a building. More energy means more GHG emissions.
What might help?
Planting vegetation on roofs would have the following effects.
In short, having lots of vegetation on roofs will reduce GHG emissions and make urban areas a cooler, more pleasant place to live.
How feasible is it?
Green roofs can come at a cost as the extra weight of plants, soil and water requires stronger, reinforced roofs. It has been estimated that this cost will be more than the savings from energy – 13% adoption of green roofs by 2050 would cost 815 billion US$.
Are there any other benefits?
What can be done?
Creating incentives for construction companies to build or retrofit green roofs will principally come from building and urban planning policies. Therefore, the most impactful thing an individual can do is to write to their local pollical representative and show support / demand for green roofs.