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Green Roofs – Can We Protect Ourselves?

How can we build in a way that avoids natural disasters, support community, and leaves us more healthy? Sounds idealistic and near impossible, but there are solutions out there. We can build in a way that benefits people and the planet alike.

What’s the Problem?


Rain rushes through streets and floods homes. Air that feels thick and heavy. Summer heat from which you are only safe in parks. Anyone who lives in the city knows these problems. These problems are caused by the way we deal with our environment, or more precisely, how we build on it. This process is called land sealing. 

What does land sealing mean? Land sealing involves all types of unnatural ground cover, for example by buildings and roads. In a broader sense, this also includes the roofs of houses. Land sealing prevents rainwater from seeping away or evaporating. It also leads to a decline in plant life, which is important for keeping our air clean and cool.

In the end, land sealing leads to flood disasters caused by rainwater, as we have recently experienced in Germany, Austria, or China. It also contributes to air pollution, cause the dust is not absorbed by plants – every day over 1000 major cities around the world exceed the WHO recommended long-term exposure limit of 10 micrograms of particulate matter per cubic meter. This leads to illness or death. Ultimately, land sealing is one reason why our planet is heating up more and more – with that, the health and climate catastrophe is pre-programmed.

But what can we do about it? 

Green Yourself!

Of course, we can’t stop building houses, roads, and roofs. But we can be more careful with nature. One possibility is greening houses. Greening parts of buildings such as roofs and exterior walls have a positive impact on reducing overheating of urban areas, keeping the air clean and storing rainwater. Another possibility is partaking in tactical urbanism.

Cooling the Air

Studies show that green roofs reduce the surface temperature of buildings by an average of 11°C on a summer day compared to conventional roofs made of roof tiles, corrugated sheet metal or roofing felt. Green facades also lower the temperature by 2 – 15°C. The denser and more large-leaved the vegetation, the better the surface is cooled.

This has to do with the fact that the main effect of surface cooling is mainly due to shading. Nevertheless, plants reflect more radiation than conventional roofs, which thus contribute to the heating of the surroundings. Plants contribute even further to the cooling of the air when the water stored in plants evaporates. The drier and warmer the climate of the region, the stronger the cooling effect. 

Air Pollution Control

Green roofs and façades promote air quality by storing CO2 and air pollutants. In addition, they produce new oxygen. Nitrate and ammonium nitrogen in precipitation (acid rain) can also be bound in this way. Mosses in particular play a role here. Species-rich and evergreen planting ensures a cleaning effect throughout the year. Nice side effects are that house greening has a noise-absorbing effect, both for people on the street and in the houses and serves as a habitat and food source for the many important insects and birds. 

Green Roofs and Rainwater Storage

Green roofs and facades make an important contribution to rainwater management. That works in two ways: through the temporary retention of precipitation water and the delay of runoff. Precipitation retention occurs primarily through the storage of water in the plants and planting equipment The excess water flows from thereafter saturation with a time delay and over a longer period. This is called runoff delay. In this way, runoff peaks are dampened, drainage systems are relieved and the risk of flooding in cities during heavy rainfall is reduced.


Of course, not everyone can now go to plant the roof or façade of their house. For one thing, it’s a not-so-affordable affair that requires skilled labour. Moreover, most of us probably live in rented accommodation and have no influence at all on the design of the building. Nevertheless, each of us can contribute by placing plants outside our front door, on our balcony or in our garden. If everyone would do that, the impact could be enormous. 

And if you have already planted all the corners of your home, go out into the street, plant shrubs and flowers along the paths and show your neighbours that you care about the naturalness of your environment, our health and the climate.

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