In a 2025 study, Penn State researchers tested porous PMMA sheets that reflected 96.4% of sunlight; a test box stayed 14.7°F cooler than the outdoor air

Innovative researchers have crafted a groundbreaking porous plastic sheet that cools without any electrical input. By reflecting sunlight and emitting thermal radiation into the cosmos, a test box made of this material maintained a notably lower temperature than the surrounding air. This eco-friendly technology showcases significant energy conservation possibilities in cooling systems, with promising initial applications in building siding and roofing to help mitigate cooling demands.