Norway has a strong growth in low-energy buildings in the recent years, and about 100'000 low-energy houses are already built,
or are in the construction or design phase (state 2007). Adequate technologies for heating, cooling and ventilation are needed
for this rapidly emerg-ing market.
Heat pumps are seen as a promising solution for heating and cooling of low-energy buildings due to high energy efficiency,
utilisation of renewable energy sources, great flexibility in system design and heating capacities, and the fact that relatively
high energy prices und low interest rates are favourable when investing in relatively expensive heating technologies.
The focus of the Norwegian national project are feasibility studies for the application of heat pump systems using natural
refrigerants in low-energy houses, prototyping and field monitoring.
A feasibility study of a central CO2 heat pump water heater for a low energy block of flats has been carried out.
Four different system configurations have been simulated in order to identify the system layout with the highest SPF.
Simulations results prove that the CO2 HPWH has a 20% higher seasonal performance factor than conventional HPWH.
Thus, the CO2 HPWHs are seen as promising solution for central water heating of low energy apartment houses.
The system concept is depicted in
(
Fig. 1).
Fig.1 6.5 kW CO2-B/W heat pump with tripartite gas cooler (left) and performance evaluation (right)
(source: Justo Alonso, Stene, 2010)
Moreover, CO2 heat pumps for space heating and DHW for the application in low energy and passive houses have been investigated.
A tri-partite gas cooler has been identified as best solutions combined with a low temperature heating system, where the cold water
is preheated in a first part of the gas cooler, the space heating system is heated in the middle part of the gas cooler and the DHW
is reheat in the third part of the gas cooler where the hot CO2 vapour enters after the compressor.
SPF comparison shows that at a DHW demand of about 50%, which may be reached in passive houses, brine-to-water CO2 heat pumps will
outperform the state-of-the-art B/W heat pumps available on the market. Results are documented in the final report on prototype systems.
Furthermore, a 3 kW integrated propane water-to-water heat pump for space heating and DHW has been developed in co-operation with the NTNU.
A prototype has been designed and lab-tested at the NTNU. Presently, the prototype is installed in a passive house of a de-sign heat load
of 2.9 kW in Flekkefjord in Southern Norway.
The prototype is connected to a floor heating system and monitored for two heating periods 2007/08 and 2008/09.
In the first heating period, optimisation potentials have been identified and the prototype has been optimised.
Results are documented in a
System concept sheet and in the
final report on prototype systems.
The Norwegian participation in IEA HPP Annex 32 is supported by
Enova SF.
