Gas or geothermal energy - advantages / disadvantages?

Good day,
last week we were at the planner for the first time, who is now working on the first draft of our new detached house. It will be about 140 sqm, 1.5 stories, and without a basement. Four of us will live there. For some time now, I have been wondering about the heating.

I have already spent hours wandering through the vastness of the internet trying to get a clear picture. My current findings:

Groundwater heat pump -> I could actually imagine it well, but since we live near an open-pit mine, I cannot predict how the groundwater in the surrounding area might change due to this.

Air heat pump -> I am not convinced... in cold winters, efficiency is too low and there are also disturbing noises.

Geothermal heat pump / collector -> was one of my favorites, but not feasible due to our plot of land.

Geothermal heat pump / earth probe -> my current favorite - disadvantage: most expensive to purchase (unexpected costs for drilling?).

Oil -> I rule this out, large space requirement that I would rather use differently.

Pellets -> I also rule this out, large space requirement that I would rather use differently.

When I told the planner about my current favorite, the geothermal heat pump with earth probe, she brought up the topic of "gas heating." Heat pumps cost up to 25,000 euros and no longer really pay off... Houses are now so well insulated that gas is not that expensive for a single-family house anymore. The increased investments would never be recouped, in her opinion... and the gas connection is already in the street...

Now I have read again that a pure gas condensing boiler is not really possible because a certain energy standard must be met for new buildings. Therefore, only a gas condensing boiler with solar thermal (for hot water) would be feasible and probably also sensible. The problem here is the orientation of the house/roof... which does not allow a southern orientation of the collectors. Only east or west would be possible and therefore it is rather inefficient?

What do you think about this? Do you think that the geothermal heat pump would pay off compared to the gas condensing boiler? Or does it not make much difference in a new building and the higher investments are not worthwhile? Or maybe it does because the solar thermal system cannot be used to its full extent?

Estimated costs:
Geothermal heat pump with earth probe: 25,000 euros
Gas condensing boiler with solar thermal: 12,000 euros

New build location near Cottbus (so far east).

Hello,

have you already included the gas connection in the EUR 12,000.00 for the gas condensing boiler with solar thermal?

A few thousand euros will be gone there as well, and suddenly you're not so far away from a heat pump...

How about an air-water heat pump with a photovoltaic system on the roof?

With the right sizing, you could then heat and provide hot water at zero cost in the future.

Regards,

Dirk

So we faced the same question a year ago...

Have Gas prepare a detailed offer in this regard, because often the connection costs are only flat-rate up to a certain distance, our connection from the property/street boundary to the utility room is 30 meters, 10 meters of which are included in the connection flat rate, we would have had to pay extra for the remaining 20 meters and in the end (with a small solar thermal system for hot water support) it was 15,000 euros, geothermal energy with deep drilling was then 20,000 euros. Since I save the chimney sweep and the heating installer, who depending on the system should adjust/check/set the gas heating annually or every two years, and also do not have to worry about a gas accident happening to us, we decided on geothermal energy. If you want to calculate properly, you should also include the electricity costs for the gas boiler... it’s not much but nothing works without electricity.

Our solar would have been mainly west, slightly south oriented...

How about the option of an ice heating system? It should already be available for your needs in the size of a small clarifier system (2.5 m wide, 2-3 m deep concrete shaft) we looked into that back then as well... for smaller plots that would be something... I don’t know the costs offhand, I only know from our deep builder that it works well (he installed it at his daughter's house). Otherwise, there are the mini combined heat and power plants, but I think that’s ruled out for you due to space reasons...

Hello,

have you already included the gas connection in the EUR 12,000.00 for the gas condensing boiler with solar thermal system?

How about an air-water heat pump with a photovoltaic system on the roof?

I found the following overview on this:

Gas condensing unit floor-standing 3,300 to 5,000 euros
with integration of solar thermal 11,000 to 13,000 euros

I think this is calculated without the connection.

Isn't the air-water heat pump the same as my above-described air heat pump? Basically with a fan in front of the house that draws heat from the air?

So, we faced the same question a year ago...

Have a detailed offer made for gas, because often the connection costs are only flat-rate up to a certain distance; our connection from the property/street boundary to the utility room is 30 meters, 10 meters of which are included in the connection flat rate, the remaining 20 meters we would have had to pay extra for and that totaled (with a small solar thermal system for hot water support) 15,000 euros, geothermal heat with deep drilling was then 20,000 euros. Since I save the chimney sweep and the heating installer who according to the system should adjust/check/set the gas heating annually to every two years and also don’t have to worry about a gas accident happening to us, we decided on geothermal heat. If you want to calculate properly, you should also include the electricity costs for the gas boiler... it’s not much but nothing works without electricity.

Our solar system would have been mainly west, slightly facing south...

How about the option of an ice heating system? It should already be available for your needs in the size of a small clarification system (2.5 m wide, 2-3 m deep concrete shaft); we also looked into that back then... For smaller plots that would be something... but I don’t know the costs off the top of my head, I only know from our earthworks contractor that it works well (he installed it at his daughter’s house).
Otherwise, there are also mini combined heat and power plants, but I think that is ruled out for you due to space reasons...

Our gas connection is in the street... so to the house it might be just the 10 meters. And our solar collector would also be oriented west, so not optimal either.

Our property is not really that "small"... it covers 905 sqm. The problem is that from north to south there is a drinking water pipe running over it and at a distance of 2.5 meters on each side nothing may be built over (except for paving).
Otherwise, we would have decided on the surface collector...

How deep is the drinking water pipe due to an "Überbauung"? The collectors are at a depth of 1.50 - 1.80 m. So that you only leave a berm where the pipe runs and can lay closer to it on the left/right sides.

But there are more options for geothermal energy, trench collectors, energy fences, and spiral baskets (just google that and you will find quite a lot).

We have, for example, compact collectors instead of "normal" surface collectors, maybe those would work for you too.

Isn't the air-to-water heat pump the same as my air heat pump described above? Basically with a fan in front of the house that extracts heat from the air?

Not quite. An air-to-air heat pump extracts heating energy from the air and transfers the heat using air (a blower) into the house. Sufficient for passive houses.

An air-to-water heat pump also extracts heating energy from the air, but then transfers the heat into the house using water as the medium (e.g., classic underfloor heating). Sufficient for "normal" (Kfw 70, etc.) houses.

Both basically operate with the "fan" you mentioned. This "fan" basically works like a refrigerator running backwards. The compressor unit can be located either outdoors or in the basement.

Regards,

Dirk