Ground source heat
What does ground source heating cost?
In recent decades, as the technology and equipment have evolved, the costs of ground source heat have decreased significantly from what they used to be e.g. in the 1990s. The costs of ground source heat are always site-specific, and largely depend on the system installed.
The costs of ground source heating are affected by:
- The costs of implementing the brine circuit, i.e. usually the cost of drilling a ground source heat well
- The costs of the ground source heating system (the size of the property to be heated and the demand for domestic hot water)
- The costs of installing the ground source heating system.
In renovation projects, additional costs may incur from e.g. electrical alterations or the possible dismantling of the old system.
Drilling a ground source heat well affects the costs of ground source heating
The costs of drilling a ground source heat well is determined by the depth of the well, which in turn is determined by the property’s demand of heating energy – the larger the house to be heated, the deeper the well needs to be. Drilling the ground source heat well is a significant expense, so the dimensioning of the well must be sufficient also in the long run. For large apartment block projects, several wells will be needed, in which case the well field must be large enough in order to obtain sufficient thermal energy.
A heat well produces about 100 kWh of energy per metre per year. Therefore, a 200-metre heat well produces roughly 20,000 kWh of energy, and in addition, the amount of electrical energy consumed by the compressor will be obtained for heating the property.
The depth of a heat well, and thus also the costs of ground source heating, is also affected by the soil type. When drilling a ground source heat well, a steel protection pipe must be installed in the soft soil above the bedrock to prevent loose soil from collapsing and clogging the well. Ground drilling is slower than rock drilling and, in addition, the steel pipe rods must be welded together, making ground drilling more expensive than rock drilling. A certain amount of ground drilling is usually included in a quote, and the exceeding amount is billed at the price per metre stated.
The amount of soft soil also affects the depth of the well. If there is a large amount of soft soil, the well must be drilled deeper in order to reach the active depth (effective depth) defined by the dimensioning. The active depth is the depth where the water rises in the well. In Finland, the amount of soft soil is seldom large enough for the ground drilling to become so expensive as to make investing in ground source heat unprofitable. Investing in ground source heating may prove unprofitable if the suspected amount of soft soil exceeds 50 metres, and based on our experience, solid rock is found before 20 metres in 95% of the sites in Finland.
Horizontal piping between the well and the technical room
The horizontal pipes and their installation between the heat well and the technical room are usually included in the price of the heat well. If the amount needed exceeds the amount stated in the quote, the excess amount will be invoiced separately at the price per metre stated. The amount of horizontal piping needed depends on the distance between the well and the technical room.
The additional costs can be avoided by choosing the turnkey delivery option, where the quote includes horizontal piping from the heat well to the technical room. However, it is worth noting that the quote may indicate the amount of horizontal piping included in the price.
Installation of a brine circuit in the ground or a body of water
The brine circuit can also be installed in the ground or in a body of water near the property. Installing a ground source heat brine circuit in a horizontal position does not require drilling, but a trench about a metre deep is excavated for the brine circuit.
A brine circuit installed in a horizontal position requires a much larger surface area than a heat well, which in turn can be drilled even on a smaller plot. Moist clay soil is better for a ground source heat brine circuit than sandy soil because sand does not transfer energy as effectively as moist clay does. Rocky soil is also not recommended, as rocks moving as a result of the freezing of the ground can damage the ground source heat brine circuit pipe, which might cause the fluid circulating in the pipe to be released into the soil.
The brine circuit can also be installed in a body of water found near the property. Weights are attached to the pipes in order to immerse them at the bottom of the body of water. Water has a good heat transferring capacity, so the brine circuit placed in water will provide at least as much heat energy as a bored well. The pipe must be carefully dug and installed in the shore in order to prevent the brine circuit from moving with ice.
The water-immersible brine circuit can be spread on the ice in the winter or installed from a raft in the summer. Sometimes, a diver is needed to install the weights, in which case the costs may become close to the costs of drilling a heat well. The diver ensures that there are no air bags in the brine circuit and that the pipes are not placed on large rocks.
The price of a ground source heat pump
The efficiency of the ground source heat pump, and subsequently, its price, is affected by the demand for heating energy and domestic hot water. The larger the property, the higher the capacity of the ground source heat pump must be. The dimensioning of the ground source heating system of a construction site depends on the temperature zone (Finnish Meteorological Institute); in new construction projects, the heating demand is about 31–42 kWh per cubic metre of air and the demand for domestic hot water is about 1,250 kWh per inhabitant.
The costs of ground source heat in a detached house
A new detached house of 180 square metres for a family of four, with a room height of 2.5 metres, would require 13,950–18,900 kWh per year for heating and 5,000 kWh per year for domestic hot water. The estimated total demand for heating energy would therefore be around 18,900–23,900 kWh. For full power heating output, a 7 kW ground source heat pump would most likely be installed at the property. For partial power output, a 5 kW ground source heat pump would be used. NOTE: The dimensioning is indicative; the final dimensioning of a ground source heating system is always done on a case-by-case basis.
For a detached house, the costs of a ground source heating system vary between €15,000 and €25,000.
For renovation projects, the demand of heating energy is calculated based on the current energy consumption: for example, 1,000 litres of oil would correspond to about 6,500–9,500 kWh of utilized heating energy (the heating power of oil is 10 kWh per litre, and the oil boiler efficiency is 65–95%).
The costs of ground source heat in a terraced house
In addition to detached houses, many terraced housing companies have decided to switch to a more energy-efficient and cost-effective form of heating. The costs of ground source heat in terraced houses depends on e.g. the demand of heating power, the heating output of underfloor heating or radiators, and the demand for domestic hot water.
Check out the article where we discuss a ground source heat renovation project carried out for a terraced housing company in Ylöjärvi and the significant savings obtained through switching to ground source heating. Read the article here.
The costs of ground source heat in an apartment building
Ground source heat is also an increasingly popular form of heating even for large residential properties, as it makes controlling heating costs easier.
When calculating the demand for heating output in an apartment building and the overall dimensioning of the heating equipment, the energy demand for the heating of rooms, the heating output of radiators or underfloor heating, the heating output required for domestic hot water and the efficiency of the systems must all be taken into account.
The required supplied power must also be considered already at the design stage. The installation of the ground source heating system may require increasing the electricity connections. For this reason, it is worth ensuring that any increase required for the electricity connections is included in the ground source heat contract.
Hot water accumulator to meet the demand for domestic hot water
The capacity of the hot water accumulator of the Aries heat pump with its integrated accumulator is 185 litres, which is sufficient for the demand of domestic hot water of a normal household in a detached house. If the consumption of domestic hot water is particularly high or the house has, for example, a jacuzzi or other facility that requires a lot of hot water, it is worth supplementing the ground source heating system with a Gebwell water heater, for example.
Full power or partial power?
Full power dimensioning of a ground source heating system means that the system is intended to cover 100% of the peak power demand. This means that the heating of the property and its domestic hot water is done with ground heat only, without the help of any electric heaters, even during the harshest and coldest winter conditions. A full power ground source heating system is a slightly more expensive investment, but the operating costs during the coldest time of the year are lower than those of a partial power system.
The partial power system is intended to cover 60–85% of the peak power demand, which means that, during the coldest time of winter, the electric heaters of the ground source heat pump are switched on, i.e. the heating is done partly with the help of electricity. The investment costs of a partial power system are slightly smaller, thanks to a lower-powered heat pump and a slightly more shallow heat well needed, but the operating costs will be higher during the coldest winter, with heating done with the help of electric heaters at the time when the cost of electricity is high.
Comparison between ground source heat pumps is often done in terms of efficiency based on the COP (Coefficient of Performance) and SCOP (Seasonal Coefficient of Performance) values.
Installation costs of a ground source heat pump
The installation price of a ground source heat pump includes the hauling of the heat pump into the technical room as well as connecting the heat pump into the brine circuit, the heating network, and a possible accumulator or buffer tank. In addition, the installation includes the deployment of the heating system and the operating instructions.
When comparing the share of installation in the quotations for ground source heating systems, the following aspects (among others) are worth considering: does the installation price include equipment hauling, (for renovation sites) the dismantling and recycling of old equipment, the electrical work and equipment, and the domestic water connection.
Upon request, Gebwell Ltd.’s dealers can offer turnkey ground source heating solutions, which include the drilling of the heat well and a fully installed, ready-to-use ground source heating system.
The price of installing a ground source heating system at a renovation site
For renovation sites, the dismantling of the old system may bring additional costs. Connecting ground source heating into an old heating system may at certain renovation sites require the radiators to be replaced with larger ones. The old system can be left in place as a supplementary or backup system. The components of the old system, such as the accumulator, can in certain cases be used in the ground source heating system, which will reduce the costs of the ground source heating renovation.
A ground source heating system always requires a water-circulating heating network. If, for example, an electrically heated renovation site does not have a water-circulating heating system, a water-circulating floor or radiator heating network must be installed.
Surface installation of a ground source heating system at a renovation site
A surface-installed ground source heating system can be installed at the renovation site neatly and quickly without breaking any structures. Underfloor heating can be implemented at the renovation site as a surface installation by installing the pipes on top of existing tiles or by milling grooves in the tiles for the piping. The retrofitting of radiator heating is also usually done as surface installation in renovation sites.
Are you planning on installing a ground source heating system at an older property? Ask for quote on ground source heat renovation »
Replacing oil heating with a ground source heating system
Are you considering switching from oil heating to ground source heating? Many others have, too, as the price of heating oil has increased and made ground source heating an increasingly attractive option. Decades-old boilers are approaching the end of their life cycle, and the constant repair of old equipment is becoming costly.
In many cases, even just the installation of a ground source heating system alongside the old oil heating system will be profitable, as it will significantly reduce oil consumption.
State subsidy available for giving up oil heating
The ELY Centre is granting a state subsidy to owners of (semi)-detached houses for giving up oil heating. The application period for the subsidy began on 1 September 2020, and extends to autumn of 2022, or as long as there is money left from the 30-million-euro appropriation.
Switching from oil heating to ground source heating has been the right choice for many owners of detached houses.
Installation of a ground source heating system entitles you to claim tax credit for household expenses
Installing a ground source heating system in an old house entitles you to claim tax credit for household expenses. In 2020, you may deduct 40% of the expenses paid for work. The maximum credit for household expenses you can claim is €2,250 per year, which in a combined household of two adults adds up to €4,500. The credit threshold is €100 per spouse. The installation costs that would entitle you to claim the full credit would be around €11,750 [(11,750 x 0.4) – (2 x 100)].
NOTE: For the drilling of the heat well, about 90% of the price is installation work that you can claim tax credit for. In addition to the drilling, the installation of the ground source heat pump is also considered work that you can claim tax credit for.
Costs of ground source heating
Ground source heating is the most cost-effective form of heating if free fuel, such as firewood from your own forest for wood heating, is not available.
The price of ground source heating is very competitive compared to the costs of other heating methods. The ground source heat pump produces at least 3 kW of heat energy per kilowatt hour it consumes. The heating costs in ground source-heated households consist mainly of the electricity consumed by the ground source heat pump. Here is an indicative calculation example for annual heating costs of a medium-sized detached house (150 square meters) for a family of four:
|Annual heating expenses|
|Ground source heating||€680|
|Savings / year||€1,500–2,000|
|Investment income from the ground source heating investment*||10–13%|
*Investment income calculation is based on €15,000 investment costs in ground source heating
Ground source heating generates savings
Ground source heat is basically freely available thermal energy that can be utilized through installing a ground source heating system. A ground source heating system is a profitable investment that generates savings.
Plus, a cooling system practically free of charge
When considering switching to ground source heating, it is worth considering the practically free possibility of cooling the property as well. The heat well can be used for cooling during the summer. Gebwell heat pumps have a built-in readiness for cooling connection, which means that all that is needed in addition is a circulator pump. When calculating the price of ground source heating, it is also worth considering the installation and operating costs of electric cooling. Read more about ground source cooling.