As with all technologies, green roofs aren’t appropriate in every situation, but they have a significant number of benefits, even in the UK.
Don’t forget water.
Water treatment is an energy intensive activity, and as such is an important contributor to our output of carbon dioxide. Unfortunately, data on the carbon balance of the water industry is harder to find than that for the power generators, so it is often conveniently ignored.
By soaking up rain water and releasing it back into the air as the plants transpire, green roofs reduce the amount of water flowing into our treatment plants. Their capacity to soak up water helps reducing the surge of water in storm sewers as a result of heavy rain. This is a great flood prevention measure, also reducing the incidence of emergency waste water release into the environment.
Controlling the temperature.
The transpiration process requires heat to produce water vapour, this cools the entire roof. A green roof comprises a number of layers and presents significant thermal mass, and as a result it helps to keep buildings cool in the summer. Both effects reduces the need for cooling in our buildings and saving energy.
It’s true that the UK climate is a little wet during the cold winter months for green roofs provide any insulation. However, the growing number of data centres that support our communications and Internet infrastructure generate large amounts of waste heat. It’s here that the cooling effects of the green roof may be most beneficial throughout the year.
The importance of green spaces.
Green roofs could provide important benefits for biodiversity of our urban areas, by providing green spaces where most people live people, and more varied habitat for embattled wildlife.
Aside from making our built environment a better place, many species will need to move in order find a suitable habitat, thus adapting to climate change. Green corridors are an important part of this mobility within urban environments, and by created them on our roof tops we are helping species find a viable niche in a changing world.