NASA Explores Potential for Green Roofs to Lower Temperatures in Cities
Sourced from Archinect
Research undertaken by NASA has found that rooftop gardens can offer substantial temperature reductions in cities during summer months. In a study published in the journal Sustainable Cities and Society, the group used satellite imagery to measure temperatures at three rooftop gardens in Chicago compared to before the roof gardens were installed.
The research sought to understand ways of mitigating the “urban heat island” in cities, where the heat absorption and retention of materials such as concrete and asphalt can cause temperatures to be ten degrees higher in cites than in surrounding areas.
“As cities grow and develop, they need to make good decisions about their infrastructure, because these decisions often last for 30 or 50 years or longer,” said Christian Braneon, a climate scientist and civil engineer at Columbia University and co-author of the study. “In the context of more frequent heatwaves and more extreme heat, it’s important to understand how these urban design interventions can be effective.”
In place of dark-colored materials traditionally used on urban roofs, such as tar, the team explored the impact of bright rooftop gardens and green roofs, whose plants and greenery reflect the sun’s rays. To do so, the team selected three green roofs installed in Chicago in the early 2000s. Using publicly available satellite imagery and open-source software, the team compared aerials of the green roofs to images of the sites taken before installation.
The study found that temperatures were reduced in two out of the three green roofs. At one site, which contained a heavy mix of plants, average temperatures were significantly lower than before the green roof was installed in 2004.
From the Living Architecture Monitor
