Joy for Green Roofs
Green roofs are in their ‘happy place’ when there are a few hours of rain followed by a few days of brighter weather.
This time of year when one day feels like spring and the next, is back to winter, maybe quite frustrating for us, but for green roofs it’s as close perfect as it gets.
What green roofs do well is hold water, slowing down how quickly rain runs off buildings and not instantly adding to the surface water from roads and other sealed surfaces. Depending on how the green roof has been designed, it can detain or hold-on-to water for several days or even weeks after rain fall.
Then when the sun comes out the again, the plants on the roof evapotranspirate the water into the atmosphere, like a person sweating. This helps even less water go to ground, and in the summer this process will help to cool the air and reduce the urban heat island effect. So if green roofs were common place in cities, the risk of urban flooding would be greatly reduced.