Thanks to the new ‘SunSmart’ windows fitted with this coating, both air conditioning and heating can stay off longer. As a result, an average Dutch household will annually spend around 500 euros less on energy and emit 400kg less CO2, TNO has calculated.
By working with widely available and affordable raw materials, the payback period of SunSmart thermochromic windows is 5 to 7 years. That is roughly comparable to the investment in solar panels. The guaranteed lifetime of the windows is 20 years.
The Netherlands has over 7 million buildings, which together currently account for 40% of energy consumption. Moreover, the built environment accounts for almost a third of CO2 emissions. Achieving an energy- and climate-neutral built environment in 2050 requires innovations that help reduce energy consumption. In addition to solar panels and heat pumps, smart windows could soon start making a significant contribution to energy and emission reduction.
Transparent solution
There are already so-called electrochromic glass coatings on the market, which allow or block solar heat to pass through depending on the temperature. In this process, the colours of the windows will change.
The SunSmart smart windows TNO has developed do not use any energy themselves. They feature integrated temperature regulation, thanks to a temperature-sensitive glass coating containing vanadium dioxide and other chemicals. Depending on the temperature, this coating either allows infrared light from the sun to pass through or not.
TNO succeeded in getting the switching to exactly room temperature (20 degrees Celsius). If it is colder outside, the smart window lets the sun’s heat through, so the heating does not have to work as hard. If it is warmer outside, the coating blocks heat radiation so it stays cooler inside. In all this, the coating remains transparent and the window does not change colour.
The thermochromic coating is primarily designed for temperate climates in large parts of Europe and the US. However, the switching temperature is relatively easy to adapt to other climate regions.
Looking for partners
Now that TNO has demonstrated that the Sun Smart smart windows can effectively contribute to the climate challenge, it is time to scale up the production process. The pilot plant in Geleen is already in full operation. By 2025, the thermochromic windows will be ready for large-scale production, making the technology commercially interesting as well. For market introduction and commercial-scale production, TNO is looking for partners.
For more information or a demonstration of the pilot plant, contact Eugene Veerkamp, Business Developer at TNO.
Image: lzf/Shutterstock
