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Swedish Meteorological and Hydrological Institute

01/11/2021 | News release | Distributed by Public on 01/11/2021 08:16

Urban environment design reduces local heat islands

A heatwave, with high temperatures over a sustained period of time, can have negative effects on health and can result in increased deaths. How hot it gets in a city can be influenced to some extent by how the urban landscape is designed and built. Dense building and many hard surfaces create local heat islands with higher air temperatures.

Planning for a warmer climate in an urban environment. Results from research into heat in cities from the HazardSupport project.

'The physical planning of the urban environment can provide a sound basis for dealing with heatwaves,' says Jorge Amorim, a research leader at SMHI. 'Measures to reduce warming and limit the urban heat island effect should primarily focus on direct effects within the local area, such as shady street trees and proximity to green spaces.'

A research study examining the expansion and densification of Stockholm has shown that the effect on air temperature is relatively local, with an increase in average temperature of up to 1.5 degrees during the summer. This effect is not seen at distances of more than approximately 2 km.

'As expected, we see the greatest temperature increases where natural environments or green spaces are built on,' continues Jorge. 'We have not noted any significant change in air temperature in the most central and built-up parts of Stockholm, where green spaces are not shrinking to any real extent in the existing development plans for the city.'

One reason why the densification and expansion of Stockholm has not had any major impact on air temperature is the city's position and the air exchange with nearby expanses of water and countryside.