Covering the roofs and walls of city buildings in plant life could cool local temperatures by up to 11ºC, reducing urban heat islands and saving energy by reducing the need for mechanical cooling on hot days claim researchers

A study by Eleftheria Alexandri and Phil Jones from the Welsh School of Architecture at the University of Cardiff used computer modelling to compare local temperatures in nine cities around the world. The researchers compared temperatures for buildings with bare concrete roofs and walls with the same buildings covered in vegetation.

The results show that covering buildings in vegetation has a major cooling effect. The vegetation works because its surfaces absorb less heat from the sun and so the sun does not heat the air around them in the same way bare concrete would. The study predicts that if a group of buildings in Riyadh, Saudi Arabia, were covered in plants the gap between buildings would become 9ºC cooler during the day and the gap’s peak temperature would also be reduced by over 11ºC. In the less extreme environment of London temperatures would still be reduced by over 4ºC.

Source

Building Sustainable Design