The heat source for this system is outside air. The heating circuit is operated without a buffer storage. The DHW circuit contains a DHW storage. Underfloor heating and low inlet temperatures serve as a good basis for a efficiently working heat pump system.   

In 2010, efficiency amounted to 3.5 which is above the average of 2,9 when it comes to air source heat pumps. As there was no back-up heater activity, the electrical energy demand is lower and thus efficiency is influenced positively. The fan's share is not considered separately. The DHW share of 20 % in 2010 was slightly above the average of 19 % and thus only slightly influences the system's efficiency negatively as temperatures for DHW are quite low compared to similar systems.