Rock heating is today an increasingly common choice when it comes to heating our Swedish homes. It is perceived as an economical, practical and environmentally friendly alternative to other energy sources. What exactly are the benefits of geothermal heat? And what are the disadvantages? How does geothermal heat compare with other heating systems?
With this article on the pros and cons of geothermal heat, my hope is that you will learn a lot about why geothermal heat can be a good choice and why it is not always so.
The advantages of rock heating are many, but the disadvantages are also important to know when you plan your heating. It is a significant investment to drill a hole in the bedrock and acquire a geothermal heat pump. It is a cost that is felt in the wallet, but one that provides a good return in the long run while you get an even temperature in the home, regardless of the season, and do good for the environment.
This is how geothermal heating works
Before we start discussing the plus and minus of heating investment, we will start to take a closer look at how the system works
Rock heat utilizes the natural heat stored in the bedrock. The bedrock is heated by the sun and maintains an even temperature of about seven degrees, all year round.
To extract the heat from the rock, a hole is drilled that is up to 300 meters deep; usually between 100 and 200 meters. Then a hose containing a so-called brine liquid, which remains liquid even at minus degrees, is lowered into the hole. The liquid is heated 3-4 degrees and then transferred to a heat pump which, by raising and lowering the pressure, heats it by about 40 degrees.
The pump heats the water that is discharged into the pipes for hot water and also what goes to the elements or water loops in the floor. If the home does not have water-borne heat, it will be heated with the help of a heating fan.
Drilling the hole in the bedrock takes one day and the installation of the heat pump takes place on the same day or within the next two to three days. Once this is done, the system basically takes care of itself. It is common that Plumbing companies who installs geothermal heating also performs service and repairs.
Rock heat provides a comfortable and even temperature in the home all year round. With regard to the size of the property and the quality of the bedrock, the installation company can advise on choosing a suitable heat pump and determining whether it is sufficient to drill a hole, or if any or some additional holes are needed.
An investment for the environment and the wallet
Installing geothermal heating requires a fairly extensive investment. The installation costs up to SEK 180,000, including labor costs and materials. Depending on the type of heating system you are comparing with, it may take a little different time for the investment to pay off.
When does my investment pay off?
Jämfört med exempelvis ren elvärme, kommer den att börja löna sig inom cirka fem till åtta år. A normal-sized house som konsumerar energi för eluppvärmning och varmvatten motsvarande 30 000 kWh/år, kan spara upp till 75% av elförbrukningen med en bergvärmepump. Ju större hus och förbrukning, desto ansenligare blir besparingen, år efter år.
The benefit of rock heat for the environment
Rock heat acts as a kind of converted solar energy: it is a renewable source, automatically produced by nature itself. Although the heat comes from a natural source, the system needs electricity to function. However, the rock heat pump uses only a fraction of the electricity that would be needed to heat the house alone.
From an environmental point of view, it is in any case worth mentioning that the electricity we use in Sweden does not come from fossil sources. Of course, it is also possible to supplement the geothermal heat with solar cells and thus generate the electricity that drives the system with a completely renewable energy.
The rock heating system can also be used to cool the home in the winter, by utilizing the cooling in the bedrock. It can thus be a much cheaper and more environmentally friendly alternative to air conditioning.
Environmental risks with geothermal heat
Man ska dock inte glömma bort att bergvärmen även kan medföra vissa risks to the environment. If the necessary protective measures and precautions are not taken, the wells can form an open contact surface between the ground surface and the groundwater.
Should a leak of environmentally hazardous toxins occur in the vicinity, this can cause great damage. Another serious problem that can arise is if coolant would leak down to the soil or groundwater or if salt water is pushed up into the well and spreads to nearby drinking water wells. If geothermal heating is installed within a protected area for groundwater abstraction, the requirements for precautionary measures are even more extensive.
When you own a heat pump, you are personally responsible for ensuring that no unwanted environmental effects occur in connection with installation and operation.
Variations in power and bacterial formation in the wires
Depending on which heat pump you use, you can have a slightly different effect, but usually the hot water in the pipes is not hotter than 40 degrees, which is not enough to guarantee that legionella bacteria are not formed in the hot water pipes.
This can be remedied by occasionally raising the temperature of the water by one elpatron och därmed döda eventuella bakterier.
Where in Sweden you live matters
Även själva the bedrock can be of great importance för hur bergvärmen kommer att fungera. En stor del av Sverige vilar på urberg, vilket generellt leder värme bra. På Öland, Gotland och i Skåne finns det däremot mycket kalksten i berggrunden, vilket ger sämre värmeledningsförmåga.
This does not mean that it is not possible to drill for rock heat in areas with less suitable bedrock, but the boreholes need to be deeper to get the same effect. The deeper the borehole, the more expensive it will be to drill. In southern Sweden, which also has a milder climate, an air source heat pump is thus a good and affordable alternative heat source, at a lower cost.
Make sure you can really have geothermal heat
It is recommended to contact the environmental and health protection office where you live to find out what is required for you to install geothermal heating and make sure that it is done in a way that does not damage the bedrock or groundwater.
It is also a good idea to talk to your neighbors before you start drilling the hole for heat, so that you can make sure that there are not several holes for rock heat too close to each other.
Advantages and disadvantages of rock heating
Here is a summary of the advantages and disadvantages of two common types of heat pumps. We start with geothermal heat because that's what this article is all about.
Advantages of geothermal heat:
- Good for the wallet: In the long run, geothermal heat lowers your heating costs. A long-term investment in your future finances. Low annual cost after installation is completed.
- Stable heat: The rock heat provides an even and comfortable temperature, all year round, unlike other heating systems which are more dependent on the season and outdoor temperature.
- Practical and easy to maintain: The geothermal heating system requires virtually no maintenance. After installation, which takes place on a single day, the system basically takes care of itself.
- Climate smart: Rock heating is an environmentally friendly alternative for heating hot water and the home. The heating system does not cause any emissions when the electricity that drives the system also comes from sustainable sources.
- Cooling: The rock heat can also cool the house during the summer.
- Flexibelt: Can be combined with other energy sources in a smart way.
- Root deduction: The labor cost is entitled to a ROT deduction. The cost can vary depending on how deep the hole is (between 90-300 meters, but rarely deeper than 200 meters) and which heat pump you choose.
- Location / Sound level: Can be placed so that they are insulated and not heard at all. Modern heat pumps from the best brands are admittedly relatively quiet, but to place the pump in e.g. a boiler room or in a basement means that it does not interfere at all. This possibility is of course limited by how you live.
Disadvantages of geothermal heat:
- High initial investment: Rock heating requires a considerable initial investment. The installation normally costs between SEK 120,000 - 180,000, of which approximately one third is labor costs.
- Requires drilling: You need to own land where the hole can be drilled. Contact the environmental and health protection office for information on what applies where you live
- Requires permission: You must apply for a permit for rock heating from the municipality. This may delay the installation from the time you make the decision.
- Requires the right bedrock: Not all types of bedrock are well suited for installing geothermal heating. You can learn more about this from an expert.
- Has limitations: There is a limit to how much heat the ground source heat pump can generate. If you are going to install geothermal heating, you should therefore make an accurate calculation of the home's energy needs, and make sure that the house is equipped with good insulation. If the house is the property is small you can ignore this.
Alternatives to geothermal heat: Air source heat pump
A geothermal heat pump and air source heat pump are based on the same type of technology. Air source heat pumps extract heat from the air outside the house and then dissipate it indoors via a fan heater.
Advantages of air heating:
- Affordable from the first day: The air source heat pump does not involve an equally large initial investment. In total, the price is for an air source heat pump, including installation, usually between SEK 12,000 and SEK 25,000.
- Environmentally friendly: An air source heat pump is also a more environmentally friendly alternative than, for example, pure electric heating.
- No excavation work or boreholes: You avoid excavation work and boreholes.
- No permit required: You do not need to apply for a permit to install an air source heat pump.
- You do not need to own the land: You do not need to own any land or have a suitable bedrock to install an air source heat pump.
Disadvantages of air heating:
- Restrictions: The air heat pump heats the indoor environment, but not all air heat pumps supply the home with hot water
- Affected by outdoor temperature: Compared with rock heat, the temperature is not as even all year round. The colder it is, the more must the air source heat pump work to maintain the right temperature in the home.
- Can be experienced as disturbing: While you can place a ground source heat pump in a place in the house where it is not heard, the air source heat pump causes some noise.
- Can only handle smaller heating needs: Air source heat pumps are intended for single-family homes with less heat demand. You get significantly more effect from rock heat. It can be said that if your heat demand exceeds 20,000 kWh per year, geothermal heat is probably a better option for you.
- More expensive in the long run: Although it costs relatively little to get started with air heating, in the long run your operating cost will be higher than the one you get with geothermal heat.
Which of these heating systems you should choose thus depends in part on the house's heating needs, the climate and the type of bedrock that exists in the area where you live.
What do the experts say?
Let us hear from someone who is well versed in geothermal heat:
Björn Löfstrand driver VVS-företaget Löfstrands Rör in Hudiksvall and works daily with different types of heat pumps. The company has particularly good experience of installing geothermal heat pumps. In many cases, Löfstrand thinks that geothermal heating is a good alternative for homeowners:
- Rock heat is a very safe and reliable heat source that we strongly recommend to you who have the opportunity to drill.
When the system needs to be serviced, can you as a homeowner take care of this on your own?
– Vad gäller värmepumpen, fyller man köldbäraren med en miljögodkänd biotemp med specialutrustning. Arbetet bör alltid utföras av ett auktoriserat vvs-företag. Försöker man fylla på själv ökar risken för följdproblem när det kommer till tryck och rätt blandning, vilket i värsta fall kan leda till frysskador.
What does a normal electricity consumption in a villa with rock heating cost?
– För vatten och värme går det åt ca 8000 kronor per kwh.
Do you recommend using the rock heat to cool the house in the summer?
– Man kan utnyttja bergvärmesystemet för att få tillgång till frikyla på sommaren. Frikylan är kostnadsfri och du slipper extra apparatur för att kyla ditt hus under varma dagar. Det finns inget negativt med frikyla då det normalt sett är mycket dyrare att producera kyla än värme.
Apart from service, repairs and operating costs, are there any major expenses to be prepared for, even after the installation of geothermal heating?
– En bergvärmepump håller upp till cirka 24 år. Vi lämnar 18 års garanti på de bergvärmepumpar som vi installerat. Efter att garantitiden gått ut – den dagen som det kan bli aktuellt att köpa en ny värmepump – är det förstås en kostnad som man bör förbereda sig på.
How important is it to ask for a permit before drilling for rock heat?
– Bergvärme kräver tillstånd för att man skall veta att det är riskfritt att borra och så att man inte orsakar skada i känsliga områden. Det är väldigt viktigt att du verkligen söker tillstånd, också för att allt ska finns inregistrerat för framtiden.
Rock heating in comparison with other heating systems
On their website, Löfstrands Rör in Hudiksvall rock heating compares some of the usual systems for heating.
Jämförelsen tittar på besparing och minskad miljöpåverkan.
Energy consumption 20,000 kWh:
- Rock heat
- Greenhouse effect: 1
- Operation / year: NOK 6,375.
- Pellet boiler
- Greenhouse effect: 1
- Operation / year: NOK 15,200.
- Electric boiler
- Greenhouse effect: 3
- Operation / year: NOK 27,000.
- District heating
- Greenhouse effect: 10
- Operation / year: NOK 16,225.
- Oil pan
- Greenhouse effect: 25
- Operation / year: NOK 34,200.
Read more about rock heat in comparison with other heating solutions.
Frequently asked questions about Rock Heat and their answers
Finally, we have collected some common questions that we know many people ask themselves when thinking about installing geothermal heating. Hopefully these can be of help if you are comparing geothermal heating with other alternatives to heating your home or property.
Approximately how much does the installation of geothermal heating cost?
The installation normally costs between SEK 120,000 - 180,000, of which approximately one third is labor costs. The labor cost is entitled to a ROT deduction.
How do I know which heat pump is right for me and if it is enough to drill a hole?
When you contact an installation company for a quote, you will be helped to choose the best option for your house.
If the heating system will need any service, can I contact the installation company then?
Several installation companies also perform service and possible repairs on the geothermal heating system.
Does it take a long time to install geothermal heating?
The installation usually only takes one day. It goes fast in other words.
Can I use the ground source heat pump to cool the house?
A geothermal heat pump can also produce cooling and is thus a cheap and environmentally friendly alternative to air conditioning.
How long does it take for my investment to start paying off?
Generally between five and eight years. Then you make an annual profit, thanks to your investment.
Is geothermal heating an environmentally friendly alternative?
It is a very environmentally friendly alternative. The bedrock and groundwater are heated by the sun. A small amount of electricity is required to power the system. Swedish electricity is not produced from fossil fuels. It is also possible to generate your own electricity with the help of solar cells.
Is the geothermal heat dependent on the seasons?
The bedrock maintains the same temperature all year round and this makes rock heat immune to the seasons. The indoor temperature is even and comfortable 365 days a year.
Do I need to apply for a permit to install geothermal heating?
You need to be out in good time to apply for a permit from the municipality.
How much maintenance does the geothermal heat pump require?
After installation, the system basically takes care of itself.
Summary and concluding words
It is a natural consequence that the benefits of geothermal heating such as the heating system have become such a popular way of supplying homes with heat and hot water. Rock heating means an investment in reduced future operating costs and is also a good choice for the environment. This method of heating can also cool the house during the summer months. The system is quick and convenient to install and easy to maintain.
However, some considerations must be made before a decision on geothermal heating is made: a permit must be applied for, the bedrock examined, one must be prepared for the extensive investment and consider the home's energy needs.
Compared with an air source heat pump, the rock heat pump provides advantages, especially when it comes to slightly larger houses in those parts of the country that have a colder climate and a more calcareous bedrock.
Hope the reading has been instructive and that you bring with you new knowledge about the disadvantages and advantages of this popular heating solution! Good luck with your choice