Comparing surface albedo and land surface temperature of reflective roofs across five United States Cities
Year: 2026
Type: article
Abstract: Rapid urban expansion and increasingly intense summer heat have heightened interest in reflective roofing as an urban heat-mitigation strategy. This study evaluates associations among roof type, surface albedo, and land surface temperature (LST) across five climatically distinct U.S. urban regions: Chicago, New York City (NYC), Las Vegas Valley (LVV), Los Angeles (LA), and Houston. Cloud-free Landsat 8 observations acquired during May–August from 2015 to 2024 were used to derive surface albedo from Operational Land Imager data and LST from thermal observations. A standardized sampling framework included 100 white-roof and 100 lower-reflectivity brown-roof regions of interest (ROIs) per city. Each 150 × 120 m ROI represented a rooftop-dominated urban area rather than an individual building. Spatial mapping, analysis of variance, and roof-specific linear regression were used to evaluate city-level patterns and differences between roof classes. White roofs exhibited significantly higher mean albedo than brown roofs in all five cities ( p < 0.001). However, this consistent reflectivity contrast did not produce a uniform LST response. White roofs had significantly lower mean LST than brown roofs in Chicago ( p = 0.002), NYC ( p < 0.001), and LVV ( p = 0.016), with NYC exhibiting the largest mean temperature difference. In LA, white roofs were slightly warmer than brown roofs, with a small marginally significant difference ( p = 0.049), while Houston showed no significant difference between roof classes ( p = 0.136). The spatial analysis identified the most coherent increase in surface albedo in Chicago, whereas Houston and NYC exhibited more limited or fragmented temporal changes. Within-class regressions did not demonstrate a universal inverse relationship between albedo and LST. Positive slopes occurred for both roof classes in Chicago, NYC, LA, and Houston, while the LVV relationships were nearly flat. Differences between brown- and white-roof slopes were significant in NYC, LA, and Houston but not in Chicago or LVV. These relationships are interpreted as city- and sample-specific associations rather than causal effects because roof materials, emissivity, shading, vegetation, atmospheric conditions, urban morphology, and mixed-pixel contributions were not controlled independently. The findings demonstrate that reflective roofs can be associated with lower surface temperatures, but their apparent performance varies with climatic and built-environment context. Reflective roofing should therefore be considered one component of locally adapted urban heat-mitigation strategies rather than a uniform solution.
Source: Discover Cities
Author: Rubab Saher
Institution: Purdue University West Lafayette
Language: English
Topic: Urban Heat Island Mitigation
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7224997052