Plants give buildings cool shades

28 July 2022

When heatwaves hit, planted walls have been proven to keep buildings cooler in the sun.

When the mercury rises beyond comfortable levels, you can guarantee that news sites will start to release articles offering guidance on how to keep cool, especially in the UK, where we always feel unaccustomed to these sudden bursts of heat.

Tips such as keeping curtains, blinds and even windows themselves closed in the daytime, draping damp towels around your shoulders or, incredibly, drinking hot tea, are all dished out to help us get more comfortably thorough the unusually sizzling days.

However, as hotter weather is expected to be come more commonplace as the effects of climate change increase, we need longer term strategies to help us to cope.

In the world of building design, architecture has been adapting to our changing climate in a range of ingenuitive ways. Natural ventilation, reviving the traditional courtyard design and strategic placement of windows are all classic techniques for designing cooler buildings.

Green buildings, while mainly designed to reduce the carbon footprint of construction, are also increasingly built in a way that regulates the temperature in and around them. As a recent Bloomberg article states: ‘For tropical cities, a key metric is to build structures that not only look cool, but are cool. As the global temperature rises, keeping the heat down in the tropics has inspired a number of innovative technologies, from Rio de Janeiro’s Museum of Tomorrow, which utilizes cold water from the bottom of neighbouring Guanabara Bay, to the hanging gardens of Singapore’s ParkRoyal hotel and the angled shading of the Suruhanjaya Tenaga Diamond Building in Malaysia.  What’s more, Bloomberg says, Green building credentials have economic value, too, helping reduce the running costs of a building as well as upping their market value.

But there is a way to bring the temperature down in buildings that already exist. Planting on the outside of structures has been proven to reduce temperatures on the wall by up to 20 degrees, according to an Italian study.  What’s more, the heat transferred into a building can be reduced by around 30 per cent when the outside wall is covered in plants.

Research by the RHS and the University of Reading on wall cover from ivy and hydrangea specimens found that not only does vegetation cover reduce the heat of a building in summer, they can also reduce humidity levels in the winter.

Because vegetation coverage such as living walls can be retrofitted, most buildings can feature them. And, the more there are in any street, the fresher the air will be. Green walls also have the added benefit of not taking up space, a real advantage on crowded and cramped urban streets.

As Bloomber points out: ‘By 2050, the Paris deadline for the world to become carbon-neutral, half the world’s population will live in the tropical belt, up from 40% now, and wealth, urbanization and industrialization are expected to increase faster in the region than other latitudes.’

It seems clear that the future is hotter. And while working to reduce global warming is vital, it also seems inevitable that we will need to find better ways to live with heatwaves. A green approach would be a cool first step.