# Polymer coating keeps surfaces 6°C cooler without energy 2026-08-27T03:57:37+00:00 | Governance | Indian Opinion Desk Corroboration: 1 independent outlet Researchers at Columbia Engineering have developed a pigment-free polymer coating that keeps surfaces cooler than the surrounding air without electricity. The coating uses microscopic air voids to reflect sunlight and radiate heat toward the sky, achieving cooling of about 6°C below ambient temperature in the Arizona desert and about 3°C in Bangladesh's tropical climate. The coating, which can be applied like paint, has a solar reflectance of over 96% and thermal emittance of about 97%. Published in journal Science, the study is based on passive daytime radiative cooling (PDRC), which requires no external energy source. The researchers said the material could be applied to rooftops, buildings, water tanks, vehicles and spacecraft, and they are working on coloured versions for surfaces where white is not suitable. ## Indian Opinion Analysis Passive daytime radiative cooling has been studied for over a decade, but the Columbia Engineering approach solves a key barrier: the need for special reflectors. Most PDRC designs use silver mirrors or complex multilayer structures that raise cost and hinder real-world application. This coating, applied like paint, avoids those constraints. The phase-inversion process used to trap air voids is already common in water filtration membranes, so pilot-scale production is plausible. In India's hot and humid coastal cities or the arid Deccan plateau, such a coating could cut air-conditioning loads for both new buildings and retrofits. The Bureau of Indian Standards does not yet have a rating for PDRC materials, but a US Department of Energy test protocol exists. The next check is whether the coating's 3-6°C cooling holds over multi-year weathering. ## Coverage - timesofindia.indiatimes.com Leads with fact-first engineering detail, no political framing This brief was synthesised by AI from the source linked above. Tags: Columbia Engineering, Science_journal Canonical: https://indianopinion.org/polymer-coating-keeps-surfaces-6c-cooler-without-energy/ License: Summary and commentary (c) Indian Opinion, reusable with attribution. Facts belong to the linked sources. Cite: https://indianopinion.org/polymer-coating-keeps-surfaces-6c-cooler-without-energy/#story-in-brief Review state: restored archive article, accurate at time of publication, not offered to search indexes. How this brief was made: an AI model read the report linked above and wrote this summary and analysis, which were published automatically. Published briefs are sampled every hour by an automated quality check; the editor verifies its findings and approves corrections, and corrected briefs carry a dated correction line. We do no original reporting. Methodology: https://indianopinion.org/ai-use-policy/