Geothermal heating: what it is and how it works

There are an increasing number of options for heating your home in winter while using less energy . Geothermal heating is one of them. It's a novel system that harnesses the earth's heat and can minimize gas and electricity consumption.

In the following lines, we'll tell you how it works, how much it costs, and what types of homes it might make sense for.

What is geothermal energy and how does it work?

When we talk about geothermal energy, we're not referring to capturing energy from the sun or wind, as is the case with other renewable sources. In this case, the heat comes directly from the earth's interior . A few meters below our feet, the temperature remains fairly constant throughout the year. And this stability is what allows a home to be heated (or cooled) very efficiently.

This is a system that uses buried pipes, a heat pump, and a closed circuit to capture heat from the subsoil . This provides heating, cooling, and domestic hot water with a single installation.

Capturing heat from the subsoil

The ground acts as a natural energy accumulator. It absorbs much of the heat it receives from the sun and stores it. Through a network of buried pipes, this heat is collected and transported to the home. The key is that, even if the temperatures are very low outside, there is enough heat underground to harness .

In winter, the system extracts that heat from the ground and brings it into the home. In summer, it does just the opposite: it collects the heat from inside and expels it into the ground. All thanks to a constant cycle that consumes almost no energy.

The role of the geothermal heat pump

Throughout this entire process, the heat pump is the engine that drives the system . It's basically responsible for transferring thermal energy from the subsoil to the home and vice versa.

To better understand this, we can think of a refrigerator: it extracts heat from the interior and expels it out the back. In this case, the heat pump does something similar, but instead of cooling food, it air-conditions spaces.

The underground temperature remains between 10°C and 16°C year-round. This allows the pump to always operate in optimal conditions, without the consumption peaks that occur with other systems.

Advantages and disadvantages of geothermal heating

Like any technology, geothermal heating has its pros and cons. Below, we review its main advantages and also the less favorable aspects that should be considered before deciding.

Advantages of the system

• It operates steadily all year round, regardless of the weather or time of day.

• It allows you to reduce your carbon footprint by not generating emissions during operation.

• In the medium and long term, it offers considerable economic savings compared to more conventional systems.

• It increases the value of the home, especially in new construction or energy-efficient renovations. In fact, the impact on a home with energy-efficient renovations can be significant, both in terms of comfort and market value.

• It is a comprehensive solution: it heats, cools, and provides hot water with a single geothermal installation.

Disadvantages of the system

• It requires a higher initial investment than other heating systems.

• In already built homes, major work may be necessary on the ground.

• If any part of the underground system is damaged, repair can be expensive.

• There aren't many specialized installers yet, which can complicate the process if you don't have experienced professionals.

Main benefits of the system

Beyond the general advantages, geothermal energy offers specific benefits that can make a difference in the daily life of a home.

• Energy savings : reduces dependence on electricity or gas to heat the home, which translates into energy savings in homes , with lower bills throughout the year.

• High efficiency : takes advantage of the constant temperature of the subsoil to operate with a performance far superior to that of other systems.

• Low maintenance : Once installed, they require minimal intervention. Buried pipes can last for decades without any problems.

• Quiet operation : By not relying on noisy motors, it is ideal for those seeking comfort without discomfort.

• Respect for the environment : by not consuming fossil fuels or emitting polluting gases, it is a clean and sustainable alternative.

Aspects to take into account before installing it

Before embarking on the installation of a geothermal heating system, there are several technical and practical aspects to consider that will determine the viability of the project.

• Type of terrain : must be suitable for drilling and have sufficient space for excavations.

• Distance between the holes and the house : It's recommended that they be about 4 meters apart. If there's not enough space, they can be drilled under the house, although it takes longer.

• Machinery space : Construction sites require specialized equipment that requires minimal maneuvering.

• Energy demand : The higher the demand of the property, the more cost-effective the system is. It's often a good fit for single-family homes.

How much does it cost to install geothermal heating?

The price depends greatly on the size of the home and the type of land . For a house of about 180 square meters, a complete geothermal installation costs around €22,000. If underfloor heating is also installed, the cost rises to around €28,000.

Per square meter, the cost would be approximately:

• Geothermal only : 122 euros/m²

• Geothermal with underfloor heating : 159 euros/m²

Example for a 120 m² home:

• Without underfloor heating: 17,000 euros (142 euros/m²)

• With underfloor heating: 21,400 euros (178 euros/m²)

It seems like a high investment, but it pays for itself in 8-10 years and then it's all savings.

Factors that influence price

The budget can vary greatly depending on various factors. These are the most important:

• Energy demand of the property : a poorly insulated or very large house will require more power.

• Location and climate : In cold areas, the pump's effort will be greater.

• Type of terrain : drilling clay is not the same as drilling rock or sand.

• Thermal capacity of the subsoil : influences the performance of the system.

• Pump power : The bigger the house, the more powerful it will need to be.

• Labor, licensing, and regulation also impact the final price.

An example budget for a 170 m² house would be something like this:

• 10 kW pump: 10,000 euros

• ACS accumulator: 1,600 euros

• Vertical probes (200 m): 7,000 euros

• Labor: 2,500 euros

• Regulation and start-up: 1,400 euros

• In total, it would be around 22,500 euros.

Comparison with other heating systems

According to data from Energanova, geothermal energy has the highest efficiency compared to other options such as gas, diesel, or aerothermal energy. Although the initial investment is higher, the annual costs are much lower.

In addition, the lifespan of the geothermal system can exceed 50 years with proper maintenance .

Is geothermal energy right for my home?

Not all homes are the same, and not all plots of land are suitable. Therefore, before deciding on this heating system, you need to consider certain requirements.

Land requirements and type of housing

The type of installation will depend primarily on the available space and the composition of the soil.

• Vertical probes : These drill to great depths (up to 100 meters). They are ideal for small plots of land or urban areas.

• Horizontal probes : These require at least 200 m² of land. They are more economical, but require more free space.

In addition, the type of soil also plays a role. In clayey or rocky soils, heat transmission is more efficient. In sandy soils, more meters of pipe may be required.

To be on the safe side, it's best to conduct a prior geotechnical study to confirm the system's technical and energy viability.

Possibilities of combination with solar energy

When combined with solar panels, geothermal energy can take savings to the next level. While solar energy generates electricity during the day, geothermal energy provides constant heating and cooling.

This type of hybrid installation allows :

• Use panels for daily electrical consumption.

• Maintain a stable temperature with geothermal energy, even on days without sun.

An efficient, sustainable and increasingly common combination in single-family homes.

In short, if you're thinking of building a house from scratch or doing a major renovation, geothermal heating is a very attractive option. It's not the most economical option initially, but its efficiency, durability, and environmental friendliness make it a smart long-term investment.

Is it suitable for everyone? No. But if the terrain allows it and you're looking for an efficient, clean solution that eliminates the need for rising gas and electricity bills, geothermal energy may be a good option.

To carry out this energy renovation or any other project you have in mind, there are financing options . There are different types of mortgages you could take advantage of. Of course, as always, it's a good idea to carefully review the terms and make sure they fit your needs.