Smart Surfaces, Smart Cities: Reducing Heat and Promoting Equity in Urban Areas

By Hillary Aidun

The summer of 2021 underscored that we are all affected by climate change impacts, whether in the form of heatwaves, fires, or extreme flooding. But some Americans are far more affected than others. Urban centers are hotter than rural areas due to urban heat island effect, a phenomenon caused by pavement, buildings, and other surfaces in cities that absorb and retain heat. In the United States, urban heat island effect results in a temperature difference of up to 7.2 degrees between cities and their surrounding rural areas. Moreover, within cities, extreme heat disproportionately harms communities of color and low-income communities. As climate change continues to raise baseline temperatures and make deadly heat waves more likely to occur, addressing urban heat island effect has become an urgent issue.

For this reason, cities are increasingly interested in adopting “smart surfaces.” The term refers to a set of surface technologies that allow cities to better manage sunlight and rainwater, including: (1) surfaces that reflect light such as light-colored pavements, parking lots, and rooftops (white roofs); (2) surfaces that provide shade such as trees and rooftops covered with vegetation (green roofs); (3) green infrastructure such as bioswales, raingardens, and other natural systems that reduce stormwater runoff; (4) porous surfaces that reduce stormwater runoff; (5) solar photovoltaics, which convert sunshine into electricity and provide shading; and (6) combinations of different types of smart surfaces. Smart surfaces reduce temperatures in the immediate term by absorbing less heat than dark and impervious surfaces. Additionally, by avoiding excessive heat, smart surfaces can achieve greenhouse gas emission reductions by decreasing the need for electricity to cool buildings. As a result, smart surfaces serve as both a climate change mitigation and a climate change adaptation measure.

While cities have many policy options for expanding smart surfaces, they also face certain legal barriers. This white paper discusses those barriers and seeks to offer potential solutions to local governments.

Read the report Smart Surfaces, Smart Cities: Reducing Heat and Promoting Equity in Urban Areas in Columbia Law School's Scholarship Archive.