Central Heat Pump feeds internal loop which feeds individual Heat Pumps

Heat distribution and temperatures levels

Different supply temperature levels can be provided, and each heat pump may be optimized for its own purpose. Also, for this reason, local temperature lifts might or might not be present. Since the water loop could be at a lower temperature level, distribution losses are not high.

Size of building, number of apartments

This solution is suitable for all sizes of buildings with the preference for larger buildings where higher investment is possible. It can overcome the limitation of high temperature terminals since a local lift of temperature can be anitcipated.

DHW and storage characteristic

Normally, a local HP for DHW is present, using as its heat source the water coming from the central HP (or district loop). Since the local temperature lift could be relatively low, enabling instant production, water storage might not be installed.

Energy standard, insulation level 

This concept can be used for buildings with a high as well as a low level of insulation. More applicable for older, not refurbished buildings with a higher heating energy demand. When applied to new, refurbished buildings, the target is to further enhance their energy efficiency.

Complexity of installation

In case of retrofitting, the old heating distribution system can be maintained. In some cases, a partial or complete exchange of radiators in each apartment may be required. In case of new buildings, long piping through the whole building is necessary.

Heat Sources

There are two “levels” on which the question of heat sources arise: the central HP and the decentral, individual ones.
For the central HP, all possible heat sources are per se eligible. It/they can be sourced via boreholes, ambient or exhaust air, water, et cetera.
The decentral HPs however can – by definition of this solution – only be sourced via the internal loop which is provided by the central HP

Specific issues of the concept

Potentially, more than one HP is installed to satisfy the need of a single appartment. The potential of the individual (local to the apartment) HPs being smaller might not have a big impact on the price level.

Positive aspects

• Splitting functions lead to higher efficiencies

Negative aspects

• Matching the capacities of local and central HPs can be tricky
• Cost