ᐅ And what type of heating system?

Geothermal energy provides cooling??? No, no, no...

Florea schrieb:
But I think geothermal energy is very long-lasting... because if the inside of the Earth no longer provided cold (which is heated by the heat pump), then there would be no life left on our planet, right?

Hello Florea,

No, no, no, you’ve completely misunderstood – it’s called geothermal HEAT, not geothermal cold 🙂

The Earth, especially at the right depth, is warmer than the outside temperature in winter, for example.

A geothermal heat pump “taps into” this geothermal heat and the temperature difference to the outside air, bringing that heat into your home.

Please read this to understand all the advantages and disadvantages:

A heat pump (geothermal heating) uses electricity from the grid to operate a compressor, which extracts additional heat from the ground or groundwater. This means that for every unit of electricity used, you get 2 to 3 units of free heat from nature.

Advantages of geothermal heating

(+) Low space requirement, no storage space needed
(+) Completely safe operation
(+) Fully automatic, therefore very convenient
(+) Low operating costs, if the conditions are right
(+) Environmentally preferable to oil or often also gas heating

Disadvantages of geothermal heating

(-) Only economical for well-insulated houses
(-) Initial investment costs are higher than for other heating systems; always calculate total costs
(-) Often an additional electric heater is needed in the bathroom to quickly heat the room
(-) An additional system for domestic hot water is beneficial, as the heat pump’s efficiency drops significantly when heating to the higher temperatures required for hot water; this also causes extra costs
(-) The ecological balance is worse than for pellet heating because electricity in winter is still largely produced from fossil fuels
(-) Large garden space needed (or costly deep drilling)
(-) The maximum possible flow temperature is limited (guideline around 60°C (140°F)); this may be insufficient for radiator heating and poorly insulated buildings (so be careful when upgrading your heating system without thermal renovation)
(-) Using a heat pump just for domestic hot water alongside an existing conventional heating system: calculate whether hot water production combined with the main heating in winter and solar thermal in summer might be cheaper

Conclusion: High upfront costs, only worthwhile if conditions suit you, and you always have to pay for 1 part electricity to get 2-3 parts geothermal heat.

Also, no one guarantees that the drilled geothermal point will remain sufficiently warm in a few years to heat your house!

This means you might need re-drilling after some years, which, as you probably know, is very expensive.

Here are some useful links on heat pumps:
Heat pump, requirements for optimal operation

Different types of heat pumps:
Heat pump, geothermal heating, heat sources

An overview of heating options from oil to heat pump:
Energy sources (geothermal, pellets, oil, natural gas, district heating, ...)

All in all, for me personally—and according to a specialist magazine from 2008 on heating and solar energy—the combination of solar energy (for domestic hot water) with a stove that burns some type of wood (firewood, wood chips, or pellets, possibly a combination stove for pellets/wood chips) that can support both heating and hot water when solar isn’t sufficient, is more economical for most people than the combination of solar and a heat pump.

Have both options calculated for your particular house and your specific energy needs, because it varies depending on insulation and house size.

Weigh the pros and cons, including ongoing costs (also maintenance), and warranty for durability (as mentioned, nobody guarantees geothermal will stay as warm underground forever!), and consider how easy and costly it would be to repair a potentially broken part of the heating system you choose.

And what do you do if, as some do (for cost reasons), you live in rural or even urban areas and a power outage occurs? Then you can forget about your (fairly electricity-dependent) heat pump and hope you have a large buffer tank full of hot water to rely on for a while!

Or, as we plan, have a small combined heat and power unit for emergencies that can produce backup electricity.

For these deep drillings, you usually need a permit from your city or municipality, which may not always be granted due to groundwater issues; if you want to use groundwater as a heat source, you will definitely need permission.

So, read everything carefully—the Austrian site is very informative anyway, so check it all out 🙂

Best regards
Honigkuchen

This is all very interesting. We are planning to start building in the next few weeks, and our architect is really pushing us to finally make a decision regarding the heating system.

I have concerns about almost all the options.

Ground source heat pumps:
1. Drilling 150 to 200 meters (490 to 660 feet) deep. If everyone does this, I wonder how it affects the earth.
2. They require electricity.

Heat pumps:
They consume a lot of electricity. Thirty-five years ago, using electric heating was considered completely unreasonable.

Pellets:
Is wood really an unlimited renewable resource? And I also wonder how pellet prices will develop in the future.

And last but not least: you need a basement as large as those old oil storage cellars.

Sure, oil is a no-go. Maybe natural gas after all?

Thanks for your assessments.

Best regards

Making a statement like this is difficult without knowing the specifics of your plot, how the house is oriented, and so on. Therefore, here are some basic points regarding the options you mentioned. Please note that these systems may partly influence your house design, and you might need to make adjustments.

Geothermal Energy:

Basically, there are three ways to use geothermal energy: through geothermal probes, ground collectors, or energy baskets. Before using geothermal probes, you need to determine how many and how deep the boreholes must be, as this affects the cost. Ground collectors or energy baskets are installed approximately 1.2 meters (4 feet) deep in your garden. It is important that the garden is large enough and not shaded by buildings or plants. This means you should ideally have more than just a green lawn in your garden; adding a pond later on might be out of the question. Overall, this option is relatively expensive, so thorough planning and getting quotes are essential to avoid the worst-case scenario of a home that doesn’t get warm enough. Inside the house, sufficient space must be allocated for the system equipment and the buffer tank. Costs are difficult to estimate as they depend on the complexity but generally range between €10,000 and €20,000.

Solar:

Here, the key factor is whether your house is properly oriented to use solar energy efficiently. A roof pitch of 45 degrees with a south-facing orientation is ideal; other configurations are less economical but can still yield worthwhile returns. Solar can be used to support both hot water and heating, but it cannot fully cover the heating demand. In addition to the required roof area, you will need a space inside the house for the system equipment and the buffer tank, which is necessary for all systems. The cost for a package for hot water production is about €4,000 for collectors, storage, and control (e.g., a system like the Viessmann Vitosol).

Wood:

Certainly environmentally friendly, as wood is a renewable resource and carbon-neutral. If you want to use wood in the form of pellets, you need to consider this during house planning. A chimney is required if one is not already planned. Furthermore, a sufficiently large storage room or a buried tank in the garden for the pellets, as well as a corresponding area for the system equipment, must be planned. Costs are around €11,000 to €14,000 plus pellet tank and installation. A wood stove is also an option but is only suitable for supplemental heating. A chimney is mandatory, but permits may not be granted everywhere due to fine dust emissions.

Gas:

Today, only modern condensing gas boilers are used, which do not require a chimney. Purchase costs are around €5,000, making this an excellent value compared to other systems. The advantage of gas heating is its high supply reliability; for example, if a lot of hot water is needed (visitors) or if demand changes (young children), it can deliver this reliably and economically. Combining a gas boiler with solar support for hot water and heating is sensible. Some manufacturers offer special combined solar systems for this purpose, such as Buderus or Vaillant. Costs with Buderus or Vaillant range between €7,000 and €14,000.

I recommend you visit the Initiative Erdgas pro Umwelt site. There you will find all the information and even a video explaining the technology.

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How can the specified primary energy limits be met for a larger house?

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Together with your designer (if they have the expertise) or as a team with your designer and an energy consultant, you develop a concept for the house. In the first step, the property is ideally insulated; in the second step, you decide on a system design based on the user requirements. However, the main factor is always the available overall budget. In my opinion, it is better to decide against expensive brickwork and instead choose the most cost-effective heating system.

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We also want to have an indoor pool. How should it be heated? Both cost-efficiency AND comfort are important to us.

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A private pool is, of course, a cost factor that must be taken into account in the system design. Especially considering that I know many pools that were eventually shut down due to costs, long-term management must be ensured. This can realistically only be done by using solar energy. If the sun is absent or not sufficient, you ensure with gas that the pool is always warm. Even without an indoor pool, there are many reasons to opt for a gas heating system with hot water preparation and heating support if you want to heat your home economically and comfortably.
The pool requires a larger buffer tank and a larger collector area. Due to the planned heating support, the collector area needed will be quite large and must definitely be taken into consideration during planning.

Thank you for the great answer. I will pass this on to our paid professionals (architect, construction manager, and structural engineer responsible for the energy-saving regulations). Let’s see what they say.

However, I had also estimated such a technological approach as the best option based on many individual pieces of information.

Thank you.

There are also water-carrying fireplaces that can help support the hot water and heating systems......