Waste Heat Heat Pump vs. Ground Source Heat Pump

Dear forum members,

In the course of searching for the right building contractor, we are, among other things, bothered by the question of the "right" or suitable energy concept for our Kfw55 / Kfw40 house.

The shortlist includes the ground source heat pump and also an exhaust air heat pump. Basically, we tend more towards a ground source heat pump due to the relevant advantages that can be read about online. Since houses are increasingly insulated and virtually "airtight packaged," we are also considering installing a central ventilation system with heat recovery.

Now the second alternative comes into play ... the exhaust air heat pump. I have already read quite a bit about this online, and it has not necessarily made me feel positive. Layman’s terms:
- I fear that the system is so sensitive that when the windows are opened (e.g., for a short airing), the system has to draw significantly more energy from the electric heater.
- The same applies to cold days, which can lead to uncomfortable drafts of cold air blowing inside.
- I have also read that a cycle can occur when the system has to provide energy to heat the hot water tank, taking it from the ambient air. Fresh air must automatically flow in, which in turn has to be brought to the desired room temperature. I’m no energy expert, but there is a catch somewhere.
- What about summer and opening the patio doors? How does the system behave in that case?

As I said, I am just a layman and have difficulty dealing with the topic of exhaust air heat pumps. Do you have experience with this? Which system (ground source vs. exhaust air heat pump) would you recommend from your point of view?

Thanks ... we are grateful for any advice.

Best regards Olgus

I would choose a ground source heat pump. That is a trouble-free technology. The problem is the hot water with air heat pumps, especially with waste heat. You have to remove a lot of cold or supply heat. Especially in the range above 40 degrees, the pump also loses power and then a lot of air volume has to compensate for this.

The geothermal heat pump and also an exhaust air heat pump are in the final selection.

I agree with you about an exhaust air heat pump, but why are you interested in a brine-water heat pump when building a simple single-family house? Advantages? Rhineland greetings

In the end, it is the price / the choice of the GÜ/GU - what does the brine-water heat pump + centralized controlled residential ventilation cost you compared to the exhaust air heat pump? What does your preferred GÜ / GU offer? What can they do? You won’t be heating inadequately with either - especially if you are aiming for KFW40. How about an air-water heat pump as a third alternative?

Hello everyone and thank you for the feedback at a late hour. Yes, indeed, an air-water heat pump is also an option, although I am rather deterred by it due to the following aspects: - lower efficiency compared to a ground-source heat pump .. although I have read that it is now roughly equal - durability compared to the ground-source heat pump - maintenance intensity - noise nuisance The apparent disadvantages are advantages of the ground-source heat pump ... at least according to my layman's understanding ... and the BAFA subsidy is still added on top. Why shouldn't a ground-source heat pump be considered for a single-family house ... have I overlooked something significant? Thank you all

It's just expensive to acquire - even if you deduct the 4.5 T€ ;-) You should also clarify whether drilling is allowed - alternatively trench collectors; of course, a lot of space is needed for this.