Can trees help cool your home in the summer heat? A new study in Hammarby Sjöstad invites residents to take part in measuring the impact of greenery on urban temperatures – indoors and out.
Hammarby Sjöstad is one of three selected districts in Stockholm where temperature data will be collected continuously throughout the summer – both outdoors and indoors. Residents can contribute by reporting how they experience heat during the warmer months.
We are living in a warming climate, and cities are especially vulnerable to heat. In Stockholm, there are 180 “urban heat islands” larger than one hectare where temperatures can exceed 35°C during heatwaves. But temperatures vary significantly, even within the same city.
“In Stockholm, as in many other Nordic cities, our buildings were designed to retain heat – not to keep it out. So what are our low-energy options for cooling? Trees and greenery are part of that answer,” Mörtberg continues.
The function of trees and vegetation is not just about providing shade. When it rains, leaves capture some of the water, which later evaporates into the air. Trees also draw water up from the ground through their trunks and branches, releasing it from their leaves – a process that cools the surrounding environment.
Combining science and citizen input
What makes this project unique is its combination of scientific temperature measurements and local experiences of heat – both indoors and outdoors. In Hammarby Sjöstad, garbage trucks and cargo bikes will be equipped with scanners that record surface temperatures around the neighborhood.
Residents and workers in Hammarby Sjöstad can take part by reporting how they experience the heat, contributing valuable insights to future urban planning. The research team hopes people will report regularly throughout the summer – via computer or mobile. You can use this link: bit.ly/varme-sommar2024 or scan the QR code, and save it as a favorite for easy access.
“We know trees provide shade – but how much impact do they really have? For example, how tall do trees need to be to affect how residents experience indoor heat? These are the kinds of questions we hope to answer, and the insights could lead to better planning for future urban areas,” says Ulla Mörtberg.
Text: Carina Näslundh
