Purdue University engineers develop ultra-white paint for radiative cooling

Engineers at Purdue University have developed an ultra-white paint capable of reflecting up to 98.1% of sunlight, a significant improvement over existing commercial heat-rejecting paints that typically reflect between 80% and 90%.

Led by Professor Xiulin Ruan, the research team utilized a high concentration of barium sulfate and specific particle sizes to scatter a broad spectrum of sunlight. This formulation allows for sub-ambient radiative cooling by reflecting solar radiation and emitting accumulated heat as infrared radiation, potentially reducing the need for air conditioning.

In outdoor testing, the paint maintained surfaces approximately 8°F (4.5°C) below ambient temperatures under strong midday sunlight and approximately 19°F (10.5°C) below ambient temperatures at night. When applied to a 1,000-square-foot roof, the technology could theoretically provide 10 kilowatts of cooling power. The manufacturing process is designed to be compatible with standard commercial production, and patent applications have been filed through the Purdue Research Foundation.