Smart Windows Passively Driven by Greenhouse Effect

The rational thermal management of buildings is of major importance for the reduction in the overall primary energy consumption. Smart windows are promising systems which could save a significant part of this energy. Here, we introduce a double-glazing system made with a thermochromic metal–insulator transition material and a glass layer separated by an air gap which is able to switch from its insulating to its conducting phase thanks to the greenhouse effect occurring in the separation gap. We also show that this passive system can reduce the incoming heat flux by 30% in comparison with a traditional double glazing while maintaining the transmittance around 0.35 over 75% of visible spectrum.