What is a geothermal heat pump?
%25203%2520(1).webp)
Stefano Fonseca is an energy and environment engineer with over six years of experience in technical building equipment (TGA). He combines technical expertise with a passion for understandable communication. For more than five years, he has been writing as a freelance editor about renewable energy and sustainable living, in particular about photovoltaics and heat pumps.
Geothermal heat pumps use the constant heat of the ground so that they heat buildings efficiently. How exactly does this technology work, what investments are required and what experience is there? In this article, you will learn everything you need to know about brine-water heat pumps.
What is a geothermal heat pump?
A geothermal heat pump is a heating system that extracts heat from the ground and uses it to heat buildings and generate water. They are one of the most efficient Heat pump types, as soil temperatures remain relatively constant all year round. They are therefore a sustainable alternative to gas or oil heating systems.
How does a geothermal heat pump work?
A geothermal heat pump extracts heat from the ground using a geothermal heat exchanger and transfers it to a refrigerant. This evaporates even at low temperatures. A compressor increases the pressure of the gaseous refrigerant and thus its temperature. The heat obtained is transferred to the heating system via a heat exchanger. The refrigerant then relaxes, liquefies again and the cycle starts all over again.
.png)
The geothermal heat exchanger is filled with brine — a water-glycol mixture that absorbs geothermal energy and transports it to the heat pump. Because of this heat transfer fluid, the geothermal heat pump is also known as a brine-water heat pump. There are three types of geothermal heat exchangers: geothermal collectors, geothermal probes, and geothermal heat baskets.
geothermal heat collectors
Geothermal collectors are an extensive system of pipes that uses geothermal energy close to the surface. This means that they will be laid horizontally in the ground at a shallow depth - usually 1.2 to 1.5 meters. They remove heat from the soil and transfer it to the heat pump via the circulating brine.
.png)
In order to be able to absorb sufficient heat, geothermal collectors require a large plot of land. This is approximately 1.5 to 3 times the living space to be heated, depending on the soil conditions. This area must not be sealed, as the upper floor area absorbs additional heat from solar radiation and precipitation. Since temperatures at this depth are subject to seasonal fluctuations, geothermal collectors are less efficient than deeper systems such as geothermal probes, but represent a cost-effective alternative.
geothermal probe
Geothermal probes are pipes inserted vertically into the ground that use underground geothermal energy. To do this, they are drilled between 40 and 100 meters deep into the ground, depending on soil conditions and heating requirements. A brine circulates within the probes, which absorbs the stored heat from the depths and transports it to the heat pump.
.png)
Since the temperatures at these depths remain largely constant throughout the year, geothermal probes are particularly efficient and provide high heating capacity even in winter. Compared to geothermal heat collectors, they require only a small area, but require a more complex installation with deep drilling. Since these boreholes can reach into groundwater, geothermal probes require approval and are subject to strict requirements to protect the water protection area.
geothermal energy baskets
Geothermal energy baskets are compact, spiral-shaped pipe systems that are recessed vertically into the ground at a depth of about 1.5 to 4 meters. They remove heat from the soil and transfer it to the heat pump via the circulating brine. Due to their design, they can be installed on a smaller area than geothermal heat collectors, but require a larger number so that they achieve the same heating output.
.png)
Since geothermal heat baskets do not reach as deep as geothermal probes, they are generally not subject to any approval requirement. They are particularly suitable for smaller plots of land and can be flexibly adapted to the available space conditions. However, they are more susceptible to seasonal temperature fluctuations, as the soil layers close to the surface cool down faster than deeper layers of the earth. However, they are cheaper than geothermal probes
How much does a geothermal heat pump cost?
A geothermal heat pump costs between 15,000 and 38,000 euros, including installation. The purchase costs for the heat pump itself are usually between 10,000 and 18,000 euros. In addition, there are assembly costs, which can amount to between 5,000 and 20,000 euros, depending on the system.
The following table gives an overview of the costs depending on the geothermal heat exchanger:
The costs of a geothermal heat pump depend on the type of geothermal heat exchanger, the soil conditions and the required heating capacity. Deep drilling for geothermal probes is more expensive than area collectors or soil baskets. Hard floors make the installation even more expensive. In the case of area collectors and soil baskets, the earthworks can in some cases be carried out by yourself, which reduces costs. Government funding significantly reduces investment costs.
Are geothermal heat pumps promoted?
Geothermal heat pumps are powered by Federal Funding for Efficient Buildings (BEG) supported with subsidies and low-interest loans.
- When replacing an old heater, the KfW subsidy 458 are used that up to 70% of eligible costs takes over. The maximum subsidy for a single-family home is 21,000 euros.
- In addition, the KfW loan 358/359 available, with an effective annual interest rate from 0.01% is granted. It can be used in addition to subsidies and offers loans of up to 120,000 euros per residential unit. households with an annual income below 90,000 euros benefit from particularly favourable conditions.
Is a geothermal heat pump worthwhile?
Geothermal heat pumps are particularly economical due to their high efficiency, as they only cause low operating costs. Especially with a Heater replacement Does the investment pay off because government Subsidies of up to 70% that cover eligible costs. As a result, acquisition costs are significantly reduced and amortization is faster. In well-insulated buildings, a geothermal heat pump is an environmentally friendly and cost-effective alternative to conventional heating systems.
The following calculation example shows that a geothermal heat pump over a period of 20 years Save almost 20,000 euros can — thanks to lower operating costs and government subsidies.
What is the experience with geothermal heat pumps?
Experience reports show that geothermal heat pumps are an efficient and sustainable heating solution when they are correctly planned and installed. Users praise in particular the low operating costs And the reliable heating capacity, even at low outdoor temperatures.
However, some testimonials indicate that the Drilling work for geothermal probes can be complex and expensive. In a Experience report in the Energiesparhaus Forum Homeowners report unexpected additional costs due to complicated soil conditions or groundwater problems.
Even in Heat pump forum It is emphasized that a Professional drilling planning is crucial is so that problems can be avoided later on. The correct sizing of the system significantly influences efficiency and long-term savings.
Are geothermal heat pumps also efficient in old buildings?
A recent Fraunhofer ISE heat pump field test proves that geothermal heat pumps can also work efficiently in old buildings. As part of the “WP-QS in Existing” project, the efficiency, operating behavior and sound pollution of heat pumps in existing buildings were investigated. The interim results confirm efficient operation even in older buildings.
The efficiency of a heat pump depends largely on the flow temperature of the heating system. Lower flow temperatures increase system efficiency.
Is my property suitable for a geothermal heat pump?
Whether your property is suitable for a geothermal heat pump depends on Area, soil conditions and groundwater situation off. For geothermal heat collectors Do you need a large, undeveloped area, as the collectors are approximately 1.2 to 1.5 meters deep be moved. Earth probes require less space, but require deep drilling up to 100 meters. Efficiency depends heavily on Soil thermal conductivity off. Loamy and moist soils store more heat than dry, sandy soils. One previous soil analysis provides certainty about the suitability of the property.
The following table provides an overview of the requirements of the various geothermal heat exchangers:
How long does a geothermal heat pump last?
A geothermal heat pump lasts on average 15 to 20 years, while geothermal probes or collectors in the ground have a lifespan of up to 50 years have. The actual shelf life depends on the quality of the system, maintenance and the correct sizing. A high-quality model with regular maintenance can be 80,000 operating hours achieve what is more than 20 years of use corresponds to. Closed geothermal probes are particularly durable as they have no moving parts in the ground.
What permits are required for a geothermal heat pump?
Depending on the system, you need a geothermal heat pump different permits. geothermal probes are usually subject to approval, as drilling in groundwaters Can be enough. Responsible is the Lower water authority, which checks whether there are water protection requirements. geothermal heat collectors As a rule, they do not require approval, as they are laid close to the surface. However, one can Advertisement with the municipality be necessary. Before installation, you should check with your municipality or the responsible environmental authority to avoid delays.
What are the advantages and disadvantages of geothermal heat pumps?
Geothermal heat pumps are particularly efficient and result in low operating costs. Since they use the constant heat of the ground, they are independent of the outside temperature. However, they require higher investment costs and complex installation.
Is an air source heat pump the right choice?
Whether an air heat pump is the right choice depends on individual circumstances. It is particularly worthwhile in well-insulated buildings with a low flow temperature and can save money in the long term through government funding and low operating costs. It is particularly efficient in regions with mild climates or in combination with photovoltaics. For poorly insulated old buildings or very cold temperatures, an alternative heat pump or a hybrid solution may be more suitable.
autarc: Your partner for efficient planning of heat pumps — find out more now!
Rely on quality and expertise when planning and installing heat pump systems. With our heat pump check, you receive comprehensive support so that you can implement your projects efficiently and sustainably. Contact us today and benefit from our expert knowledge!