Performance assessment of sageglass electronically tintable glazing

SAGE Electrochromics have developed a glass coating which can be controlled electronically to be clear or tinted, reducing solar heat gain and glare in buildings whilst remaining transparent and therefore not blocking views out. The glazing can be controlled in a variety of ways, including integration into the building management system (BMS). The potential benefits of installing SageGlass electrochromic glazing in office facades for four different European climate zones have been assessed, comparing the performance of SageGlass against a number of typical façade systems for each climate zone. Performance metrics such as energy consumption, CO2 emissions, utility costs, chiller sizing, chiller cost, lettable area impact and façade cost were assessed. In order to analyse the performance of SageGlass, a control methodology had to be developed and implemented into the DTM software to allow for dynamic switching of the façade states. This algorithm was assumed to be implemented via a BMS to minimise unwanted solar gain during summer, whilst ensuring sufficient daylight was admitted to reduce artificial lighting energy consumption. Results showed that SageGlass was able to provide performance benefits in the following areas: Reduced annual energy consumption, and therefore lower CO2 emissions and utilities costs. Optimised daylight penetration through the façade, and control of glare, whilst maintaining thermal comfort conditions and outside views for occupants. Removing the need to add external shading devices to control solar gain with no impact on net lettable area. Reduced peak cooling demand with similar or lower costs than comparable façade systems. These benefits were found to be enhanced in warmer climate zones.