With the heating you can contribute a lot to climate protection.

An average single-family house with gas heating emits around 5 tons of CO2 per year, more than half of the total energy-related CO2 emissions of an average German.

Vestaxx GmbH from Berlin offers an innovative window heater which, according to its founder Andreas Häger, represents a climate-neutral and significantly cheaper heating solution for new buildings.

These windows work with electricity and are intended to compete with the heat pump.

The company, in which five people work, was founded in 2019, but the idea for window heating came up earlier.

Häger worked for Schüco, a building supply company that wanted to integrate solar panels into the facades it sells.

Some solar panels have a layer of zinc oxide over the solar cell that heats up when current is passed through it.

The electrical engineer Häger experimented with this layer by installing it on glass, causing the pane to heat the area around it.

Vestaxx GbR was founded in 2014.

Häger remembers the start-up's very first order well.

"The order was for a spa hotel built in 1850." The seminar room could no longer be supplied via the radiators because they were dirty on the inside due to their age.

"We installed six panes of glass and were actually certain that this room with two outer walls could not be heated sufficiently with the heating panes alone." It was early January and it was minus 15 degrees outside.

"Shortly after the installation, I got a call from the site manager who asked me how he could lower the temperature," continues Häger.

Three layer window

The Vestaxx heating window consists of three panes.

The inner pane is coated with zinc oxide on both sides.

This layer is highly transparent and conductive.

The middle and outer panes are covered with an equally highly transparent layer of silver, which is used to reflect the thermal radiation from the zinc oxide layers.

Normal windows are more permeable to thermal radiation, which leads to higher heat loss, explains Häger.

The gaps in the window are filled with argon gas, which is particularly suitable for thermal insulation.

According to Häger, this means that 95 percent of the heat is radiated into the interior of the house.

The windows are not much thicker than regular double-glazed windows.

The actual heating process takes place in the zinc oxide layers on the inner pane, through which current with a voltage of 230 volts is conducted.

Some of the electrical energy is then converted to thermal energy because of the electrical resistance in the zinc oxide.

About 40 percent of this energy is released into the air convectively, i.e. directly through physical contact.

The remaining 60 percent of the thermal energy is given off as radiation, explains Häger.

These then hit solid bodies such as walls or people who would be heated.

The thermal radiation ensures that the entire room heats up.

The heating of the body by radiation is said to be beneficial.

“The rays penetrate deep into the tissue and stimulate blood circulation.

The same feeling develops on the skin as with the sun's rays," explains Häger.

According to the Federal Office for Radiation Protection, moderate amounts of long-wave thermal radiation have a positive effect on well-being.

Safe for children

According to Vestaxx windows, the maximum temperature on the surface is 50 degrees, well below the limit for a risk of burns.

The windows are also safe for children.

The company does not manufacture itself, but in partner companies.

According to Häger, the windows can be opened normally because they are connected to the power supply via a cable in the hinge.

According to their own statements, they are maintenance-free and react much more quickly to temperature changes than a conventional heat pump.

The windows are currently only available in Germany and neighboring countries, but there are plans to expand across Europe.

“The gas crisis in particular is currently causing many to rethink.” Windows are only installed in new buildings;

As a rule, old buildings cannot be sufficiently heated with them.

According to Häger, a window of one square meter costs 500 euros.

A new house with 150 square meters of living space with built-in Vestaxx heated windows has a heating requirement of 4500 kilowatt hours of electricity per month, which costs around 135 euros.

Since there were no gas costs and you can also produce up to 60 percent of the remaining house electricity yourself with a solar system, the total energy costs, including house electricity, could be reduced to less than 100 euros.

The company's customers are mainly private customers, but also large customers from the economy such as the window companies Rekord from Itzehoe and Wagner from Niederwürschnitz.

According to the company, it sold 600 heated windows in 2021 and achieved sales of 350,000 euros.

Revenue has doubled every year since it was founded.

"We are in a phase of exponential growth," says Häger.

The article comes from the student project "Youth and Business", which the FAZ organizes together with the Association of German Banks.