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CO2 Heat pump system for combined heating and cooling of non-residential buildings


CO2 heat pumps installed in non-residential buildings will achieve a high COP as long as the heat is rejected over a large temperature range and the return temperature in the heat distribution system is relatively low. In European non-residential buildings high-temperature radiators are commonly used to cover the space heating demand, and a CO2 heat pump rejecting heat to only radiators will achieve a low COP due to the high return temperature. However, in many non-residential buildings the demand for heating of ventilation air after the heat recovery unit constitutes a relatively large share of the total heating demand of the building. Consequently, by making a serial connection of the radiator system and the ventilation heater batteries it is possible to obtain a relatively low return temperature and with that favourable operating conditions for a CO2 heat pump. Preheating and reheating of hot water will lead to a further increase in the COP for CO2 the heat pump system. Computer simulations have demonstrated that a CO2 heat pump system in non-residential buildings can achieve the same or higher seasonal performance factor (SPF) than heat pumps using conventional working fluids as long as the heat distribution system is designed for a low return temperature. The operational time of the ventilation system will have a major impact on the SPF of the CO2 heat pump, since the return temperature in the heat distribution system is considerably lower when the ventilation system is switched on. The construction of a prototype CO2 heat pump system for heating and cooling of a Norwegian non-residential building is now being planned. The nominal heating capacity of the CO2 heat pump will be in about 150 kW, and it will be designed as a single-stage unit using an inverter controlled reciprocating compressor


Academic chapter/article/Conference paper





  • SINTEF Energy Research / Termisk energi
  • SINTEF Energy Research / Gassteknologi
  • SINTEF Energy Research




International Institute of Refrigeration


Proceedings : 22nd International Congress of Refrigeration : Refrigeration creates the future



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