The many benefits of a green roof

Back in 1995, Chicago experienced a serious heatwave. The emergency services were overrun as people succumbed to heatstroke, and when it was all over, the authorities paused to consider why it happened and what could be done to prevent it happening again. One finding was that the city had overheated, and they should introduce new measures to reduce the ‘urban heat island’ effect.

The eventual result is that Chicago now has more green roofs than anywhere else in the United States – over 500 of them, including schools, offices and civic buildings. Chicago also boasts the largest green roof in the world, and the first organic rooftop farm in America.

Few places have gone all-in on green roofs the way that Chicago has, and they remain quite rare. We’d certainly like to see more of them, because there are many benefits to a green roof.

Let’s start with temperature. Green roofs can absorb heat, while water evaporating from the plants has a cooling effect. This keeps buildings from overheating and makes them more comfortable for those inside. It also reduces the need for air conditioning, which of course saves money and the carbon emissions from running them. That’s especially important in a warming climate, where heat waves are becoming more likely.

While we’re on the topic of what’s good for the environment, green roofs obviously provide an added area of plant-life, which is good for pollinating insects in particular. A slate or EPDM rubber roof is a dead space. A green one is alive, a pocket of natural space that will benefit bees and butterflies.

Other environmental benefits include trapping dust and pollution, which helps to clean the air. Green roofs also absorb rain and slow run-off. As water soaks in and drains more slowly from the roof, it prevents gutters and drains from being overwhelmed, especially during sudden or heavy downpours.

Green roofs can also help to dampen noise. That might be protecting those outside the building from what’s going on inside – music lessons for example. Or it could be about creating a quieter environment for those inside the building – such as reducing the distraction of passing traffic or aeroplanes taking off from a nearby airport.

There are aesthetic benefits too. We think living roofs are attractive in their own right, but they can also help a building to blend in with its surroundings. This can be important in some contexts, and is sometimes even a condition of planning permission. Where schools have leafy green grounds for example, a living roof can enhance the overall effect.

We like living roofs at Green Modular, and we fit them regularly. If you’re considering one on your new building, get in touch. We’d be happy to answers any questions you may have.