Low emittance coatings and the thermal performance of vacuum glazing

• Published in: Solar energy 2007, Vol.81 (1), p.8-12
• Main Authors: Fang, Yueping, Eames, Philip C., Norton, Brian, Hyde, Trevor J., Zhao, Junfu, Wang, Jinlei, Huang, Ye
• Format: Article
• Language: English
• Subjects: Applied sciences; Buildings; Buildings. Public works; Energy; Exact sciences and technology; External envelopes; Finite volume method; Heat conductivity; Heat transfer; Insolation; Low-emittance coating; Miscellaneous; Natural energy; Opening. Closure. Circulation (stairs, etc.); Solar energy; Thermal performance; Vacuum glazing; Vacuum technology
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2006.06.011

The thermal performances of vacuum glazings employing coatings with emittance between 0.02 and 0.16 were simulated using a three-dimensional finite volume model. Physical samples of vacuum glazings with hard and soft coatings with emittance of 0.04, 0.12 and 0.16 were fabricated and their thermal performance characterised experimentally using a guarded hot box calorimeter. Good agreement was found between experimental and theoretical thermal performances for both a vacuum glazing with a soft coating (emittance 0.04) and those with hard coatings (emittance 0.12 and 0.16). Simulations showed that for a low value of emittance (e.g. 0.02), the use of two low-emittance coatings gives limited improvement in thermal performance of the glazing system. The use of a single high performance low-emittance coating in a vacuum glazing has been shown to provide excellent performance.