Dynamically adaptive window design with thermo-responsive hydrogel for energy efficiency

Abstract

Energy-efficient smart windows with dynamic modulation of solar heat gain in response to external stimulus such as ambient temperature variation have been of great interest. However, when a smart window technology is implemented over a commercial glazing system, its performance could be dramatically influenced by the pre-installed low-e coating. An implementable smart window component made of thermo-response hydrogel for dynamic solar modulation, either prefabricated with window structures for newly constructed building application or manufactured into a film for existing building retrofit, has been rationally designed in this work. An IR-reflective coating was integrated with the as-synthesized hydrogel film and the ultimate solar regulation performance has been evaluated. Compared to the bare hydrogel sample, the total light modulation ability from the hydrogel film with IR-reflective coating was tapered by 0.9–5.4% due to the blockage of a portion of IR radiation before transmitting through the hydrogel layer. This additional NIR blocking effect allows this window design preferably suitable for hot weather with high solar radiation. Annual energy simulations to a prototype commercial building have shown the thermo-responsive hydrogel window component prepared in this work yields annual space cooling energy savings of up to 8.1% for Tucson, AZ, USA, which gives a 30.6 kWh/yr·m2 cooling energy savings per square meter of window glass.