Passive Cooling of Structures with Thick Film Nanocomposites
Abstract
Passive cooling via state-of-the-art cool roof coatings can significantly drop roof top temperatures by reflecting nearly every wavelength of electromagnetic radiation incident upon its surface. Reflective coatings reduce a large amount of electricity air conditioning units consume and lower peak electricity loads. This paper presents a method to drop surface temperatures even further for a greater cooling load reduction and energy savings, but also to tailor cooling power for colder climates to avoid costly heating load increases during winter weather. The method combines reflective cooling with radiative cooling with a thick film nanocomposite coating. Radiative coolers selectively emit heat through the earth’s atmospheric windows to the cold of outer space while reflecting electromagnetic radiation outside the atmospheric windows to passively cool terrestrial objects. Passive radiative cooling is a popular research topic – it is interesting that experiments demonstrate radiative cooling through numerous fabrication methods and material combinations. However, many radiative cooler fabrication methods rely upon nanoscale precision in a controlled environment for uniform multi-layer thin films or nanostructures. While less complex methods encase dyes or nanoparticles into very thin polymer films which may not be suitable for 24-hour exposure to environmental conditions or application to many structures. Hence, passive radiative cooling technology is still not cost-effective, scalable, and robust enough to be extensively commercialized like cool roof coatings. Experimental results are presented on a new direction of research utilizing selectively emitting nanoparticles in nanocomposite thick film as a low cost, scalable, and robust technology to increase and tailor passive radiative cooling of surfaces.