Dutch invention turns your facade into a noiseless heat pump outdoor unit

The heat recovery façade basically consists of a circuit of pipes in metal cladding. The fluid in that circuit is heated by the sun, and when it is not shining, heat is extracted from the air. Then the heated water is used as a source for the heat pump or temporarily stored in a buffer. That sounds very simple, yet a path of innovation preceded the launch.

The system was launched last week by paint manufacturer AkzoNobel, facade builder Aldowa and the manufacturer of the heat-generating facade, start-up Emergo Calosol. The façade is fitted with solar collectors that use the entire façade surface for heat generation. So there is no need to install an outdoor unit, and this setup therefore makes no noise. "It is an alternative to a ground source," explains Peter Bussink of Calosol, "because it is a water-water system.

Colored collectors

Thanks to a specially developed coating, the energy from the invisible part of sunlight is also harnessed. To capture this, AkzoNobel developed a new type of paint in collaboration with TNO. Thanks to the innovative coating, in the future the surface can have a color of your choice while still absorbing the heat optimally. 'Even a white plate, which normally hardly gets any warmer in the sun, becomes really warm with this coating,' says Bussink. 'That feels very strange. But even white has a solar absorption of 40 percent.' With darker colors, that percentage is naturally higher. This gives a high efficiency even when beautiful colored collectors are applied.

The facade panels can take any shape the architect comes up with. 'It's basically normal cladding,' points out Bussink, who himself comes from the cladding industry. 'Architects have the freedom and we adapt to that. We then make the profile in the factory with the piping system in it. And then it can be assembled so completely.'

Plus points

Bussink sees three major advantages of the system. 'First of all, the system is 30 percent more energy efficient than heating with an air-water heat pump.' The second is that the system can also cool. 'We simply reverse the heat pump and then you return the heat to the facade. In the evening and night you can cool it back to the air, because the coating also gives off its heat well.' The last big advantage is that it is a very quiet system. 'You can hear a very soft hum from the heat pump, but that's negligible.'

Calosol has a tool that potential customers can fill out, Bussink says. 'You can fill in what the surface area of the facade is, the color you want and the orientation of the facade. We can then quickly calculate what the potential is in it. Anyone who wants to use that tool can contact us.'