Experiences with brine heat pump

1. How about looking it up? It's all here in the forum. I believe I have detailed everything about my construction project here in the forum far more thoroughly than most others dare to. It’s less about searching than what you yourself demand for your information (just the name of a voluntary consumption database....)... click for example on "Page 1", or is that already too much to ask? Jokester!

2. Your "delivery" (which doesn’t even match your stated source) of the 20% difference is extremely roughly estimated, your calculations are absolutely minimalist. You take some guessed monthly value and slash your treasure chest 20%. It’s also not factual, especially not the generalizations you display.

The construction costs and the planning quality are decisive for the economic efficiency.

The slightly better efficiency of a brine-water heat pump compared to a good air-water heat pump makes little difference in running costs for houses with <10000kWh heat demand. The simplest assumptions are completely sufficient to calculate this adequately. I don't understand the fuss here..

The worse the house, the colder the region and the cheaper the drilling, the more it speaks for a brine-water heat pump. Not to mention conveniences like passive cooling or the lack of an outdoor unit.

Nice that you are getting personal.. You don't need to, please don't. But thanks for the note about the 1st page.

Then with your data and with poorly assumed data for an air-to-water heat pump.

You used 2000 kWh from September to September with an annual performance factor of 5.5. Let's assume a poor air-to-water heat pump with an annual performance factor of 3.5. Roughly estimated, that means about 35% more electricity demand.

With an electricity price (for me) of 25 cents/kWh, that amounts to (700 kWh more) 175€ per year. After ten years, that's 1750€. Now comes the kicker: after 60 years, that makes your 10,500€ for the drilling.

Calculate it as you want, but realistically, a drilling usually only pays off very, very late.

Edit: for new buildings and good planning

Also see that one can calmly question the 25 years without the OP immediately taking it personally. I’ll consider it for myself: Air-water heat pump + photovoltaic, about 2200 kWh electricity with a COP of 4.5. About 1400 kWh cost me 25 cents, 800 kWh 11 cents (lost feed-in tariff) makes 440€/year, simplified with an annual performance factor of 5.5 about 360€, meaning 80€ savings per year. Over 25 years that makes an advantage of 2000€, which wouldn’t even cover the additional costs for the brine-water heat pump. No question, geothermal energy is a fine thing and I would have had a trench collector if the space had worked out. Economically, however, it is at most viable in an Alpine village, with a lot of luck.

A COP of 4.5 for an air-water heat pump is more the exception than the rule. If you look at the heat pump consumption database, the ratio is always about 1:1.3 in favor of geothermal energy. This results in a total advantage of around 4800 euros over 25 years for a heat demand of 10k. If you also include BAFA subsidies, you quickly approach 10k.

Therefore, I don't consider 25 years to be that unrealistically long when factoring in subsidies. However, I also see the drilling as a value-enhancing measure, which should not be overlooked.

Cost of trench collector under €2,500; funding €4,500. Compared to the air-water heat pump, money saved, plus lower ongoing heating costs, the passive cooling alone is worth gold, no annoying outdoor unit... annual performance factor >5.5...

Simplistic calculation, since the trench collector was built as a DIY project.. I know. But that was including planning no more than 3 days.