Improvements in Glazings: SERI Materials Research in Progress

Progress in two areas with significant long-term potential for improving the thermal performance of apertures is summarized and evaluated. Removing interglazing gasses may greatly reduce the conductive/convective thermal transfer through multiple pane glazings. Evacuated glazings now under investigation show the expected high resistance to thermal conductance and convection; laboratory-scaledemonstration units have been produced with laser sealed edges. Another approach, more applicable for cooling load offset, addresses the possibility of electrically controlling the transmission of solar radiation through windows. Electrochromic glazings can be operated by means of lowvoltage switching to adjust the visual and infrared transmittance of the aperture. Both concepts are discussed inrelation to 1. the overall goal of greatly reducing unwanted gains and losses through windows and 2. the commercially available alternatives to these concepts. Analyses of optimal characteristics and recent technical advances at SERI are described, and future research requirements are sketched.