Gas or geothermal energy - advantages / disadvantages?

For us, geothermal energy including the drilling also cost roughly 15,000 euros. The planning was around 13,000 - 14,000, but the drilling turned out to be a bit more expensive (1,500 EUR). With this price, the decision was very easy for us. See the information from - plus your solar thermal system you will then also reach these price ranges. It's good that you are informing yourself about the different options. It would be sensible to get quotes for your two favorites. But also find out to what extent geothermal energy is allowed and possibly sensible in your building region. Cottbus belonged for decades to the “brown coal heart” of the GDR and the region, to my knowledge, was still exploited by MiBrAG during federal German times. Don’t let a few “small problems” await you here.

What sizing do the collectors need to have? I once read something about twice the size of the heated area..140 sqm x 2 = 280 sqm collector area? On one side, with boundary distances, maybe 140 sqm is possible... I actually didn't want to go over the water pipe itself. Because it is also at about 2.00 meters depth.

Double the square meters of the house is the general sizing guideline where no detailed calculation is done but the heating engineer sizes it so that it definitely fits. HLB and detailed planning are required to determine the actual demand as well as the correct extraction capacity.

That makes sense for you because it is tight.

This forum cannot help with planning, there is another forum that specializes in trench collectors and where people with lots of knowledge have put in a lot of work...

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 more and suddenly you are not that far from a heat pump...

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

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

Regards,

Dirk

Unfortunately, heating at zero cost in this configuration does not work here in Upper Franconia, because in winter (currently almost 2 weeks without direct sun, 0 degrees and below) the photovoltaic system does not produce any electricity for the heat pump - just as little at night, so in winter from about 4 pm to 9 am. And precisely when I need electricity from the photovoltaic system for the heat pump, it does not supply any.

And for hot water preparation in summer, only a little electricity is needed anyway.

For your 140 sqm, my choice would be gas (but without solar) (not KFW70, but why not), an air-water heat pump (which climate region?) or a ground-source heat pump. And a drilling should not be that expensive for the energy demand of a new 140 sqm house either.

Best regards

I agree with the statement regarding HLB and planning by , even though I would generalize this statement a bit more. Have a heating load calculation done to determine your needs and sit down with a professional. Then you can move on to the final decision regarding the heating technology. In the end, that person will also be able to tell you whether a trench collector or flat collector is possible for you or not.

Also because I have read in other forums about geothermal heat pumps with ground probes for 40,000 euros...

I would also transfer the mentioned 40,000 euros to our heating installer. But including underfloor heating and complete sanitary installation

Just for comparison: We initially also wanted a geothermal heat pump with drilling. That’s why we had a hydrogeological report prepared. It then turned out that due to our clay soil, we would have had to do a total of 3 drillings at 100 m each in order to make the whole thing efficient. The drillings alone would have cost us almost 20,000 euros. In the end, we would have ended up close to the 40,000 euros as well. Although this is certainly not the norm, as you can see, anything is possible. In the end, the report cost us a bit of money, but it made it easier for us to decide against drilling.

Have a heating load calculation done to determine your needs and meet with a specialist. Then you can proceed to the final decision regarding the heating technology. In the end, they will also be able to tell you whether a trench collector or surface collector is possible for you or not.

I doubt that a "specialist" would advise a trench collector. It has not really arrived in the professional companies in Germany yet...