Impacts of radiative cooling paints for CO2 reduction and global warming mitigation

Abstract

Daytime radiative cooling has attracted significant interest recently because it uses the high reflection of sunlight and emission of thermal radiation to cool objects below the ambient temperature without power consumption. However, the year-round impact of modern daytime radiative cooling paints on carbon reduction and global warming mitigation as compared to conventional black roofs and previous cool roofs is not well understood. Here we choose ultrawhite CaCO₃ cooling paint used on buildings as a prototype system and conduct a comprehensive analysis of the impact of two distinct mechanisms on global climate. The first mechanism is carbon emission reduction at power plants due to building air conditioning power savings. The second mechanism is due to increased direct heat rejection by the ultrawhite roof to deep space, where the thermal effect is equivalent to CO₂ reduction from the atmosphere. Our results show that the impact of the paints on the climate was always positive for all climate zones, reducing up to 665 lbs of CO_2eq from the atmosphere per m² of paint applied over a 100-year span. Additionally, the paints are most effective in hot/warm/mild and dry climates, and depending on climate zone, 0.94 % − 2.02 % coverage of the paint on the earth’s total surface could stop the global warming trend.