Thermos A heat pump for hot water in the bathroom

The patented “THERMOS” system for the production of hot water in the bathroom
uses the residual heat from the home ventilation system as an energy source for a heat pump. In collaboration with Swissframe AG and other universities, an energy-efficient and economical solution has been found for the upgrading of many old buildings.

Factsheet

  • Department Engineering and information technology
  • Research focus Renewable Energies
  • Research field Environmental Technologies / Ecology
  • Funding body CTI
    SFOE
  • Duration (planned) 05.02.2015 - 01.10.2020
  • Project management Urs Muntwyler - Laboratory for Photovoltaic Systems BFH
  • Head of project Duglas Urena Hunziker - Laboratory for Photovoltaic Systems BFH
  • Project staff Balz Hegg - Swissframe AG
    Florian Ruesch - HSR University of Applied Sciences Rapperswil
    Michel Haller HSR University of Applied Sciences Rapperswil
    Stefan Bertsch - University of Applied Sciences Buchs, NTB
    Elias Büchel - University of Applied Sciences Buchs, NTB
    Roger Weber - Institute for Intelligent Industrial Systems BFH
    Joël Bärtschi - Institute for Intelligent Industrial Systems BFH
  • Project partners - business Swissframe AG
  • Project partners - research institutions incl. BFH University of Applied Sciences Rapperswil
    University of Applied Sciences Buchs
    Bern University of Applied Sciences
  • Project partners - public sector InnoSuisse
    SCCER-FURIES
  • Keywords Heat Pump, Photovoltaics, Energy Efficiency, Hot water

Starting Point

In newer apartment blocks in Switzerland, it is normal for the hot water to be produced centrally and distributed to the apartments via a network of pipes. This results in high heat and energy losses, which often amount to more than half of the hot water consumption. The taller the building, the greater the inefficiency.

The widespread alternative is an electric boiler in each apartment to heat the water. Countless older buildings have decentralised systems of this kind. These power guzzlers will need to be replaced in the medium to long term. Switching to a centralised system would result in the losses described above, and at any rate the installation of hot water pipes in existing buildings is very costly.

Approach

Now, an energy-efficient solution has been developed that is also suitable for both old and new buildings: a ready-made front-wall unit that contains all the bathroom technology and consumes very little energy. The manufacturer is Swissframe AG in Münchenbuchsee. Together with the Institute for Energy and Mobility Research IEM at the Bern University of Applied Sciences and other universities, Swissframe has developed a system that uses the exhaust air from the home ventilation system as a heat source and uses a small, highly efficient heat pump to heat the hot water storage tank.

The restricted space in the cavity, at just 30cm wide, presented a major challenge for the production of the prototypes of the individual components in the front-wall unit. For example, the water reservoir was designed as a flat cube with innovative vacuum insulation. The heat pump is very small and operates almost continuously, but uses very little power.

Solution

Thanks to the industrial prefabrication of the units for water, waste water and air distribution, the conversion to the Thermos front-wall unit takes very little time. What’s more, the water is heated by renewable energy extracted from the exhaust air of he ventilation system and supplied by solar power.

Today, Swissframe is mass-producing the front-wall unit. The new system was first installed in an apartment block with 30 apartments. Five of these units are being monitored and tested as part of a pilot and demonstration project by the Swiss Federal Office of Energy.