Philadelphia’s White-Roof Experiment Showed How a Simple Coating Could Cut Household Heat

Philadelphia's White-Roof Experiment Showed How a Simple Coating Could Cut Household Heat. In the early 2000s, the city conducted an experiment called the Philadelphia Cool Homes program, which involved installing reflective white roof coatings on around 340 flat-roofed homes owned by low-income residents. The main goal was to reduce indoor temperatures by reflecting the intense summer sun and keeping interiors cooler.

The results showed that this simple intervention substantially reduced heat at the ceiling and lowered temperatures in the rooms below. Specifically, ceiling-level temperatures fell by about 2.8°C (5°F) on hot days, and room-air temperatures at chest height fell by roughly half that amount. Additionally, the program found that air-conditioning loads were reduced by roughly one-third in a typical row house.

While the energy savings were less certain, the project demonstrated the potential benefits of reflective roof technology in combating urban heat. The city is now revisiting this technology with a new pilot program in 2025, which will deliver free cool-roof coatings to 62 households in Strawberry Mansion. The municipal officials will evaluate energy usage, indoor climate data, and household feedback following the summer of 2026 to assess the effectiveness of this updated approach.

Brief written by urgent.news from Colombia One's own syndicated text. Machine-written — may contain errors; check the original before relying on it.