Air or Ground Source Heat Pump? The Comparison for Your Prefab House

The heat pump is standard in prefab new builds in 2026 — the only question is: air-source or ground-source heat pump? Both systems heat with environmental energy but differ significantly in acquisition cost, efficiency and space requirement. This guide compares both variants and helps you make your choice. Anyone who wants to explore the basics in more depth will find them in the Prefab House overview.

How do air-source and ground-source heat pumps work?

Because the air is cold in winter, the efficiency of the air-source heat pump drops precisely when heat demand is highest. The ground, by contrast, provides a relatively constant source temperature throughout the year — so the ground-source heat pump works more evenly. Both systems show their strengths especially in a well-insulated new build with underfloor heating. More on choosing a heating system in the guide Heating in the Prefab House 2026.

Air or ground-source heat pump — what is the difference in detail?

What permit and how much space do you need?

The air-source heat pump only needs an outdoor unit and an indoor unit; a permit is usually not required, although distance and noise protection rules apply towards the neighbouring plot. The ground-source heat pump requires either a deep borehole (permit required, note water protection areas) or large collector areas in the garden. On small plots, the surface collector is therefore often ruled out — then only the borehole remains.

Check early whether your plot is suitable for a borehole; the lower water authority (untere Wasserbehörde) grants the permit. Advice on subsoil and plot suitability is given in the guide Soil Survey & Subsoil.

Which heat pump is worthwhile for whom?

In combination with a photovoltaic system and an electricity storage, the running costs of both systems drop further — right up to the energy-self-sufficient house. How prefab house manufacturers integrate the heat pump is covered in the guide Heat Pump in the Prefab House. Funding options are summarised on the Funding page.

How do the running operating costs differ?

The acquisition is only half the calculation — over the service life, the electricity costs count. Because the ground-source heat pump works with a higher seasonal performance factor, it uses less electricity than the air-source heat pump for the same amount of heat. For a single-family home with moderate heat demand, the efficiency advantage can partly offset the higher acquisition costs over 15 to 20 years. However, the exact calculation depends heavily on the electricity price, the insulation standard of the house and the JAZ actually achieved.

An important lever is your own solar electricity: anyone who couples the heat pump with a photovoltaic system significantly reduces the running costs, because part of the drive electricity is generated in-house. This applies to both systems — so the combination is worthwhile regardless of the heat source. How the heat pump, PV and storage complement each other is shown in the guide PV, Storage & Wallbox.

What about maintenance and service life?

Both types of heat pump are considered low-maintenance. A regular visual inspection, checking pressure and refrigerant, and cleaning the outdoor unit (with the air-source heat pump) are usually sufficient. The service life of the heat pump itself is usually around 15 to 20 years. The borehole probes and collectors of the ground-source heat pump last considerably longer — they are practically maintenance-free and usually outlast the service life of the technology in the house many times over.

The outdoor unit of the air-source heat pump is exposed to the weather and works audibly; when choosing the location, you should therefore plan for distance from the neighbour and from bedrooms. The ground-source heat pump stands entirely in the plant room and is barely perceptible in operation. Both aspects feed into the decision — alongside cost and efficiency.

What funding is available for heat pumps?

The installation of a heat pump is funded, whereby the programmes and funding rates change regularly. In new builds, the heat pump is often part of a funded efficiency-house standard, while separate grants apply to replacing the heating system in existing buildings. Because the conditions can change, it is worth looking at the current overview on the Funding page before you plan the financing.

With the ground-source heat pump, the higher investment can be put into perspective by funding and lower running costs; with the air-source heat pump, the lower initial investment scores points. In both cases: calculate the total costs over the service life, instead of just comparing the acquisition price. In advance, you can use our calculator to calculate the prefab house costs and assess your budget realistically.

Which heat pump suits your prefab house?

For most prefab new builds, the air-source heat pump is the obvious choice: lower investment, usable anywhere and without drilling. The ground-source heat pump shows its strengths when the plot is suitable, you plan for the long term and value maximum efficiency as well as particularly quiet operation. Since both systems work reliably in a well-insulated new build with underfloor heating, a “wrong” decision is rarely possible — it is about weighing up cost, space and efficiency.

Have the heat load calculated and several variants worked out before you commit. A prefab house provider that plans the heating technology from the start ensures that the heat pump, underfloor heating and building envelope fit together optimally. In combination with photovoltaics, this leads up to the energy-self-sufficient house; whether your new build needs a PV system anyway is clarified by the guide Solar Obligation for New Builds.