Cool White Polymer Coatings based on Glass Bubbles for Buildings
Xiao Nie, Youngjae Yoo, Hasitha Jeewana Hewakuruppu, Jonathan Sullivan, Anirudh Krishna, Jaeho Lee
Abstract
Abstract While most selective emitter materials are inadequate or inappropriate for building applications, here we present a techno-economically viable optical coating by integrating glass bubbles within a polymer film. A controlled glass bubble volume concentration from 0 to 70% leads to a selective solar reflectivity increase from 0.06 to 0.92 while the mid-infrared emissivity remains above 0.85. Outdoor measurements show the polymer coating on a concrete surface can provide a temperature reduction up to 25 °C during the day when conduction and convection are limited and a net cooling power greater than 78 W/m 2 at a cost less than $0.005/W. The impact of polymer coating on common buildings is estimated as potential annual energy savings of 2–12 MJ/m 2 and CO 2 emission savings of 0.3–1.5 kg/m 2 . More savings are expected for higher surface-area-to-volume-ratio buildings, and the polymer coating is also expected to resolve cooling issues for old buildings with no air conditioning.