The Optical Properties of Black Coatings and Their Estimated Cooling Effect and Cooling Energy Savings Potential

The optical properties of coatings pigmented with different black colorants were systematically investigated and their surface temperatures and cooling energy savings were estimated.The black coatings pigmented with chromite iron nickel black and manganese ferrite black spinel colorants are not cool enough to be energy efficient cool black coatings.The cool black coatings pigmented with NIR-transmitting perylene black and dioxazine purple colorants possess a green shade and a violet shade, respectively.The estimated surface temperature reduction values and annual cooling energy savings in Beijing range from 3.0˚C and 1.21 kWhm -2 yr -1 for the black coating pigmented with chromite iron nickel colorant to 13.8˚C and 5.52 kWhm -2 yr -1 for the black coating pigmented with dioxazine purple colorant, respectively.