2020
In this comparative simulation study, we investigated whether thermochromic glazing can outperform familiar static energy-efficient glass across different climates. Windows bring daylight, views and a connection to the outside, but they also create winter heat loss and unwanted summer heat gain. Because heating and cooling account for a large share of building energy use, a window’s behaviour has a direct effect on energy demand and emissions.
Conventional high-performance glazing is usually designed for one dominant condition. Solar infrared-blocking glass helps in hot climates by reducing heat gain; low-emissivity glass helps in cold climates by limiting heat loss. Both work well at their intended extremes, but neither can change when the weather does. That matters especially in temperate climates, where a building needs solar warmth in winter and protection from overheating in summer.
We modelled a prototype dwelling and compared commercially available static systems with thermochromic glazing developed for this purpose. Thermochromic materials change their solar-infrared behaviour with temperature: when it is warm they reduce solar heat gain, and when it is cool they allow more of it. We assessed the adaptive glass with a low-e coating across a range of climates rather than assuming one solution fits every location.
Static glazing remained very effective where conditions were consistently hot or cold. In intermediate climates, however, the adaptive system performed especially well because it could follow seasonal variation. Compared with clear glass, the modelled system improved annual energy consumption by as much as 22 percent, better than the other systems we tested. For a representative Dutch house of 172 m² with 25 percent window façade, we estimated annual savings of €638 and modelled a potential national carbon-dioxide reduction of 4.5 megatonnes with broad deployment.
These figures do not mean one material can solve building emissions by itself. They show the potential in a component often treated as fixed. Our results support further work towards market-ready thermochromic windows, especially in temperate regions where homes need to manage both cooling and heating while remaining comfortable and bright.