Geothermal energy

Geothermal energy refers to the use of heat stored within the Earth for heating, cooling, or electricity generation. In residential construction, the term “shallow geothermal energy” is used when heat is extracted from the top 400 meters of the ground-typically via geothermal heat pumps with ground probes or ground-source collectors. Unlike air-to-water heat pumps, geothermal heat pumps operate at a constant temperature level nearly year-round and therefore achieve very high annual performance factors (APF).

Technical Variants: Ground Probe, Ground-Source Heat Exchanger, and Groundwater

In the case of the ground probe, a pipe is inserted into a borehole 50 to 200 meters deep and filled with brine. This system requires little floor space and is particularly suitable for developed properties. The ground-source collector lays pipes horizontally at a depth of about 1-1.5 meters; it requires a large unsealed area but is less expensive to install. Groundwater systems (open systems) tap directly into the groundwater and operate particularly efficiently-but require permits under water laws and suitable hydrogeological conditions.

An overview of the technical differences:

Type	Depth	Space requirement	Investment	JAZ (typical)
Geothermal probe	50-200 m	Low	High	4.0-5.5
Surface collector	1-1.5 m	High (1.5 × living space)	Medium	3.5-4.5
Groundwater system	Well up to 30 m	Low	Medium	5.0-7.0
Air-water pump	-	None	Low	2.5-4.0

The annual performance factor (APF) indicates how many kilowatt-hours of heat are generated per kilowatt-hour of electricity. The higher the APF, the more efficient and cost-effective the operation.

Permits and Legal Framework

Geothermal probes require a permit under water law. In Bavaria, the district office or the independent city issues the permit; in the Nuremberg metropolitan area, the Environmental Office is responsible. The classification of the site according to the Geothermal Information System (GeotIS) and the Bavarian Geothermal Atlas is decisive: In some areas with karst groundwater or contaminated sites, drilling permits may be denied. A preliminary brief hydrogeological assessment provides planning certainty.

For ground-source collectors, a water law permit is generally not required in Bavaria, provided the system is closed-loop and the brine does not contain hazardous substances. Nevertheless, installation must be carried out by a certified specialist company.

Cost-Effectiveness and Subsidies

The investment costs for a geothermal system are typically 30-60% higher than those for an air-to-water heat pump, but the ongoing operating costs are significantly lower. A geothermal probe for a single-family home typically costs between 25,000 and 45,000 euros, including drilling and the heat pump; an air-to-water heat pump, on the other hand, costs between 12,000 and 25,000 euros. The additional expense pays for itself through lower electricity costs in 7 to 15 years, depending on electricity price trends.

Through the Federal Funding for Efficient Buildings (BEG), geothermal heat pumps are currently subsidized for up to 35 percent of eligible investment costs (plus a potential climate bonus). Additionally, Bavarian funding programs and KfW loans offer further financing options.

Geothermal Energy as a Contribution to the Energy Transition

In the context of the GEG (Building Energy Act) and the 65-percent renewable energy requirement, geothermal energy is one of the most technically elegant solutions: A brine-water heat pump utilizing geothermal energy easily meets GEG requirements and can generally be operated without further hybridization. For new buildings and extensively renovated existing buildings with modern heat distribution systems (underfloor heating, low-temperature exterior wall heating), the geothermal heat pump is often the most economical solution in the long term.

Practical Tip for Homeowners in Nuremberg and Franconia

The subsoil of the Nuremberg metropolitan region consists primarily of Middle Keuper sandstones and Jurassic limestones. Geothermal probes are generally feasible in large parts of the urban area but require individual approval. We recommend that builders submit a preliminary inquiry to the Nuremberg Environmental Office early on and consult a certified geothermal specialist with experience in the Franconia region. Especially in new development areas around Nuremberg (e.g., Erlangen-Tennenlohe, Schwabach-Nord), geothermal heating systems have already been successfully installed in many cases.

For existing buildings in Nuremberg, it should be checked whether the existing radiator flow temperature is compatible with a heat pump: geothermal heat pumps operate efficiently at flow temperatures of 35 to 45 degrees Celsius-older radiator heating systems, on the other hand, often require 65 to 70 degrees. A combination of a geothermal heat pump and radiator replacement (or the addition of underfloor heating on the ground floor) often makes economic sense.

Frequently Asked Questions

How long does a geothermal system last?

Geothermal probes have a technical lifespan of 50 years or more. The heat pump itself typically needs to be replaced after 15-20 years, while the probes remain in the ground.

Can I also use geothermal energy for cooling?

Yes. Many geothermal heat pumps offer a passive or active cooling function (natural cooling). In the summer, heat from the building is transferred directly to the ground via the probe-which is particularly economical since no additional compression operation is required.

Do I need a building permit for a geothermal probe?

Geothermal probes generally require a water rights permit under the Bavarian Water Act, not a building permit. However, a licensed drilling contractor is required for the drilling operation itself.

How much does a geothermal probe cost for a typical single-family home in Nuremberg?

Drilling costs in the region typically range from 50 to 80 euros per meter drilled; for a 130-square-meter single-family home with a 10 kW heating load, a 100-meter probe is usually required-which amounts to 5,000 to 8,000 euros for the drilling alone. Added to this are installation costs and the heat pump itself (approx. 15,000 to 25,000 euros), resulting in total investment costs of 25,000 to 40,000 euros-minus the BAFA subsidy.

Geothermal Energy and Property Value

An installed geothermal system has a positive impact on property value-both in terms of appraisal and marketing. In the energy performance certificate, a geothermal heat pump generally leads to a significantly better energy efficiency rating (Class A or A+), which directly influences the property’s market value. Buyers increasingly reward low operating costs and a modern, climate-friendly heating solution with a price premium compared to comparable properties with oil or gas heating.

In the Nuremberg metropolitan region, we observe that well-equipped single-family homes with geothermal heat pumps, solar panels, and radiant floor heating can command purchase price premiums of five to fifteen percent compared to conventionally heated properties of comparable location and size. For owners who wish to improve their energy efficiency before selling, it is therefore worth doing the math: If an investment of 25,000 to 40,000 euros in a geothermal system can be offset by an increase in value of 40,000 to 80,000 euros in the selling price, this results in an attractive cost-benefit ratio. We support homeowners in the region with this assessment and connect them with certified energy consultants to provide a sound basis for decision-making.

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