Green roofs are building roofs covered with vegetation. They are composed of several layers: the growing medium, a filter cloth to prevent clogs in the drainage system, a drainage system to prevent excess water and a conventional waterproof roof surface. They are beautiful and you probably know how beneficial they can be to our wellbeing and environment as they improve air quality, absorb rainfall and attract beneficial wildlife, such as birds and bees. But you may not know green roofs can also improve your home insulation and help you save money on bills due to reduced use of cooling and heating during summer and winter. Let’s go through 4 main benefits of green roofs.
1. They improve air and quality of life
Through photosynthesis, plants convert carbon dioxide into oxygen and are also capable of eliminating air pollutants and chemicals in the process. Because of this, green roofs are a great solution to reduce city pollution where building more parks and green areas is not always possible. When a green roof is accessible to residents, it can also be used as an outdoor leisure space to relax and enjoy with your family.
The polluting particles that are absorbed by green roofs would otherwise be incorporated into the water system through surface rainwater runoff, so they also help improve water quality. Roof plants absorb and use water from the rain, reducing excess water that could cause floods.
2. They provide insulation – save on bills!
Green roofs have positive insulating effects either in summer or winter. In summer, plants use solar energy for their organic functions and this reduces the amount of heat that is absorbed by the roofs and transferred indoors. The soil also acts as an insulation barrier that prevents heat transfer from outdoors. In winter, the soil and green layer prevent your home from losing heat to the outside. The effect in winter can be reduced if the soil is too damp and that’s why green roofs are assigned a fixed U-Value (the measure of insulation efficiency), depending on temperature and moisture conditions.
This insulation effect means that green roofs will help you save on energy bills throughout the year: reducing the use of cooling in summer and heating in winter.
3. They provide protection
A lovely garden on the roof provides additional layers that can protect the roof itself and more specifically its waterproof surface from wind and sun damage, increasing its lifespan. Roofs that are directly exposed to weather conditions can go through extreme temperatures during a single day and this can alter the chemical properties of the waterproof layer putting its physical integrity at risk.
They provide sound insulation. Not only will they protect you from noise coming from the roof, such as heavy rain falling, but also reduce sound coming from the streets, such as traffic. In a study, it was verified that replacing a standard roof with a green one can reduce outside noise transferred inside by up to 10 dBA. A human being can clearly perceive a reduction of 5 dBA in sound, so the green roof effect is certainly significant.
4. They prepare your home for the future
The reduction in green spaces to build cities has caused the increase in temperatures around urban areas when compared to the countryside. This effect is what scientists call Urban Heat Island Effect (UHIE) and is predicted to increase in the future. If you live in a big city like London, you are probably used to heatwave alerts every summer and have probably noticed an increasing need to use fans and air conditioning.
These appliances may temporarily increase your comfort in summer, but they contribute to worsening the problem in the future as they emit more CO2 and contribute to global warming. Also, even in the most optimistic predictions, it is still likely that temperatures will continue to increase. Green roofs are a great solution for cities to adapt to this future and reduce their negative effect on the environment.
Now that you’ve seen a series of reasons why green roofs are beneficial to you and the planet, we hope you are convinced to have your own. Learn more on the basics of gardening, start applying them to your new roof garden and Green It Yourself… Now!
British Horse Society Headquarters picture by Sky Garden Ltd.