Energy
A surface can sit in full midday sun and be colder than the air around it. The trick is a window in the sky
12 Sept 2026 · 11 min read
With no power, no refrigerant and no moving parts, a correctly engineered coating can hold a roof below air temperature in direct sunlight. It works by throwing heat through a narrow band of wavelengths the atmosphere happens to be transparent to — straight out to space.
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