City Pilots Pavement Surface Treatment to Reduce Urban Heat Island Effect

The City is piloting a pavement surface treatment to reduce summer air temperatures in the Springfield lot in Inman Square. This coating is applied over asphalt paving to improve the reflectivity of the surface and lower absorption of heat from the sun, especially in the summer, thereby decreasing air temperatures in the area. In addition to the environmental benefit of decreasing air temperatures, there is also a substantial benefit for people walking, biking, using public transit, and otherwise enjoying outdoor spaces in our community.

The pilot project is one of the City’s Resilient Cambridge Plan strategies to address increasing temperatures driven by climate change.  While global climate change is causing average and extreme air temperatures to increase over time, the urban heat island effect amplifies the temperature increases. The urban heat island effect happens in part because of hard materials like asphalt that absorb heat from sunlight, which then heats the air above.  Extreme heat can cause negative health effects, including heat stress and exhaustion, sometimes leading to mortality.  Extreme heat kills more people in the US annually than any other natural disaster.

In addition to decreasing the heat island effect in urban areas, this pavement coating may also improve long-term durability and crack resistance to the surface.

The color chosen for the Springfield Lot is “Sandstone” and has a Solar Reflectance Index (SRI) of 36 compared to conventional asphalt that has an SRI of around 5. The higher the SRI, the cooler the material is likely to become in the sunshine, which in turn reduces how hot the air temperature in the area becomes.

The City will be monitoring the heat impact of this new surface and evaluating its durability to determine if it’s a cost-effective way to reduce heat islands in other parts of the City. To learn more about the City’s Resilient Cambridge Plan visit: https://www.cambridgema.gov/Departments/CommunityDevelopment/ResilientCambridgePlan