New combined CO2 heat pump and solar heating system.

The Institut für Thermodynamik at the Technical University of Braunschweig ( has developed a new heating system based on a CO2 heat pump connected with a solar storage tank. A prototype was presented last June during the German Green Week (at the same time as a CO2 air-conditioning system for trucks and buses, presented by Konvekta). The heating capacity of the heat pump is about 2 kW and Braunschweig University claims that it promises to be more energy-efficient than conventional appliances using combustion. Energy demand for the hot water supply is gaining more importance as the heating of the building requires little energy, especially in houses with high insulation standards. This makes it possible to raise the operating point of the heat pump to temperatures of approximately 55-60°C, at which CO2 as a refrigerant is highly efficient.