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‘Smart windows’ should in future block heat from the sun in summer and actually let this heat through in winter so that this warms the house. Research institute TNO and the province of Limburg will present a prototype at Brightlands Materials Center on the Sittard-Geleen campus in Limburg on Tuesday. It could save an average household using an air conditioner 500 euros a year, the research institute calculated.

  • Smart windows adjust to the temperature, save up to €500 a year and reduce CO2 emissions.
  • These windows use a self-regulating coating for heat management without electricity.
  • Available to consumers from 2025, with future plans for retrofitting existing windows.

All buildings could use the smart windows. Specifically, a ‘smart window’ has a kind of coating between the double-glazing. That coating senses what temperature it is outside. If it is warmer than 20 degrees Celsius, it keeps out the sun’s heat. Colder? Then heat from the sun is allowed inside. “The user does not notice any of this, the window is as transparent as ever,” says TNO researcher Pascal Buskens.

The researchers found inspiration in hotel windows that can electronically darken the window when there is a lot of sun on it. “For that, you just need a lot more: different window frames and electricity,” Buskens explains. “A coating that switches itself is much cheaper.” TNO has calculated that the smart windows would pay for themselves within about seven years in average households. And in the meantime, households also emit about 400 kg less CO2.

TNO is investigating the smart windows further in the near future. If everything goes as expected, consumers will be able to buy them themselves from 2025. For now, windows still have to be replaced if someone wants the coating in them. TNO is still investigating how it will eventually also be possible to apply the coating to existing windows.