Outside air is used as heat source for this system. The heating circuit contains a buffer storage, the DHW circuit contains a DHW storage. Underfloor heating and low inlet temperatures provide good preconditions for the heat pump system.   

Efficiency amounted to 2.9 in 2010 and thus reflects the average of air source heat pumps of 2.9. The fan's share of 8 % of the overall energy demand lies above the average of 7 % and therefore slightly influences the SPF negatively. As the back-up heater was not used, efficiency is influenced positively. The share of DHW of 11 % in 2010 lies below the average of 19 % and thus influences efficiency positively due to the low temperature level needed for heating.