The heatwaves are over. Now is the time to prepare buildings for next summer

On one of the hottest days of the summer, the air temperature was around 34 °C. Dry, sunlit surfaces of buildings and paved areas regularly exceeded 50 °C, and in some places reached as much as 70–74 °C.

Areas with greenery showed a very different picture.

Green façades, the crowns of mature trees and vegetation near water mostly stayed between roughly 30 and 35 °C. At the entrance to the site, it was possible to see a difference of several tens of degrees side by side. While conventional façades, roofs and car parks heated up significantly, vegetation supplied with water stayed considerably cooler.

Greenery is not just about appearance

Shade is not the only reason. Plants use water and, through evapotranspiration, remove part of the heat energy from their surroundings. Available water, vegetation and shading together affect surface temperatures and the microclimate immediately around a building.

This is why a green façade is more than an architectural feature. On hot days, it can be a functional part of the building and its surroundings.

The thermal images from the LIKO-S site show this difference very clearly: surfaces that look similar to the naked eye can differ in surface temperature by tens of degrees.

Preparing for next summer starts now

Once temperatures drop, building overheating stops feeling urgent. But green façades, trees and other adaptation measures cannot be put in place overnight during a July heatwave.

If we want buildings and their surroundings to perform better next summer, changes need to be planned in advance.

Green façades aren't planned when it's 35 °C outside. They are planned now, so that next summer we don't have to tell ourselves once again that we really need to do something about the heat.