22 May 2008


There is today a clear trend towards low energy houses. Several passive houses
have been built in Sweden. However heat pumps are not installed in any of these houses.
The standard system solution is a high efficiency air-to-air heat recovery system with an
electric reheater in the supply air. About half of the domestic hot water is produced by
thermal solar panels, mostly during the summer time. The rest is produced by electricity. In
winter the heating system therefore mainly uses direct electric heating. A theoretical
comparison has been made between this solution and two heat pump solutions. These
solutions have also been evaluated for a less well insulated house. The calculations show
that in most cases the heat pump solutions give a lower total energy use and life cycle cost
than the standard solution. The ground source heat pump also has a lower peak power
demand and in addition offers the benefit of free cooling. The conclusion is that heat pumps
are a viable alternative for passive houses and also for other types of low energy houses.