Rooftop gardens can help cut heat in cities, shows study

Due to an effect called the “urban heat island,” temperatures are often ten degrees higher in cities than in surrounding areas due to the heat absorption and retention of materials like asphalt and concrete, a NASA press release said.

The Sunday Standard
Feb 2023

Excerpt:

Bright rooftop gardens that reflect the sun or “green roofs” filled with plants and greenery can alleviate some of the extreme city heat, new research by climate scientists from New York’s NASA’s Goddard Institute for Space Studies (GISS) said.

The results of the study were published in the journal Sustainable Cities and Society.

“As cities grow and develop, they need to make good decisions about their infrastructure, because these decisions often last for 30 years or 50 years or longer,” said climate scientist and civil engineer at Columbia University and GISS Christian Braneon, who was one of the study’s co-authors, reported Earth.com.

“In the context of more frequent heat waves and more extreme heat, it’s important to understand how these urban design interventions can be effective.”

The GISS research team looked at satellite images of three green rooftop sites that had been installed in Chicago in the early 2000s and compared them to images taken between 1990 and 2011, NASA said in the press release.

They looked at how much surface temperatures and vegetation had changed at the sites and in control sites nearby that didn’t make use of green roofs.

Temperatures were reduced in two out of three of the green roofs — in one of them, average temperatures were reduced significantly — though the other with lower temperatures than the control site had begun to rise again toward the conclusion of the study.

The results suggested that the success of green roofs in reducing temperatures may be determined by the diversity of the plants used, location and other factors.

Read the complete article here.