White Coatings Under the Hot Light: Motives, Means, Materials and Opportunities
As another summer season of blazing temperatures draws to a close, white coatings continue to be a subject of great fascination as well as practical interest. As their popularity grows, they are increasingly under the hot light: literally because they are being installed on more roofs, and figuratively because they are under increased scrutiny. Building professionals are asking hard questions: What are the benefits? How do they work? What are the materials? Where should they be applied?
Many building owners view white coatings as a genuine advance in roofing technology, one that can extend the lives of roofing systems and lower energy bills [2,3]. A few consultants suggest that white coatings are "over-prescribed" and perhaps even have downsides, e.g., they can become soiled or cause too much glare to surrounding high rises as well as airline pilots and air traffic controllers [4,5]. Still others campaign for off-white roofs, garden roofs, shading, light-colored gravel and other green remedies against hot summers in the city and urban heat islands [6]. One thing is certain: Interest in white coatings is reaching new heights.