Comparison of geothermal heat pump with LWW pump

Your construction company or the energy consultant can calculate that for you.

It comes down to increasing the insulation and keeping the heating load so low that the heat recovery unit of the [Kontrollierte-Wohnraumlüftung] reaches the 15% share.

This then counts as a compensatory measure.

Your construction company or energy consultant can calculate that for you.

It comes down to increasing the insulation and keeping the heating load so low that the heat recovery of the controlled residential ventilation achieves the 15% share.

This then counts as a compensation measure.

Controlled residential ventilation + gas boiler including solar thermal and 36.5 bricks + passive house windows is tight with KFW55, right? 9.9 kWp photovoltaic, as far as I have heard, does not bring anything for KFW55.

Whether it works with KFW I cannot tell you. I am building without KfW and therefore only have to comply with the energy saving ordinance.

Your construction company or the energy consultant can calculate that for you.

It comes down to increasing the insulation and keeping the heating load so low that the heat recovery of the controlled residential ventilation achieves the 15% share.

That then counts as a substitute measure.

Thank you for the information!

Hello,

exciting topic, I’ll chime in here.

We have 18 years of experience with ground-source heat pumps in two different houses. Always with surface collectors in the garden (ring trench collector didn’t exist back then). The experiences are consistently positive.

Now we are currently planning our new build, KFW55 without controlled ventilation, timber frame construction. The house builder offers, as standard, an air-water heat pump (Nibe or Viessmann). According to him, that is currently the most sensible option (gas with solar collectors almost the same price but old school, ground-source heat pump significantly more expensive and hardly pays off anymore with KFW55).

Now I’m reading here that the price differences are not that big. Although I didn’t understand the calculation:

The subsidy has now increased to 35% (all ground-source heat pump costs). I have also heard 8,000 € extra costs from many general contractors. That should fit. You get about 4,000 € more in subsidies. So that would be around 4,000 € extra cost.

The subsidy is 35%, that would be 2,800 € on 8,000 € additional costs, not 4,000 €, but never mind. What deters me (regarding our situation):
- high effort for drilling (permits)
- too small a plot for ring trench collector

So... air-water heat pump. I agree with the house manufacturer: with a seasonal performance factor of around 4.5 versus 5.5 for a ground-source heat pump, I have 18% higher electricity costs per year with an air-water heat pump. At total costs of about 1000 € p.a., that is bearable.

What bothers me more is the “rumor” that air-water heat pumps are prone to problems and have a short lifespan... does anyone have experience with this?

I’m less bothered by the outdoor unit. We also have a not-so-pretty side of the house behind the carport, adjacent to the utility room.

My idea is: we get a (small-sized) stove for the house. With appropriate temperature sensors and actuators on the underfloor heating, I could bridge the coldest winter period with it. From experience with the sluggish underfloor heating, we want to have a stove anyway.

I have read that 10 cm instead of 15 cm spacing in the underfloor heating. Does that really only cost a few hundred euros? How much is the gain in quality and reduction of the supply temperature?

Best regards, Andreas

Hello,

exciting topic, I’ll jump in here.

We have 18 years of experience with brine-water heat pumps in 2 different houses. Always with ground collectors in the garden (ring trench collector wasn’t available back then). The experiences are consistently positive.

Now we are currently planning our new build, KFW55 without controlled ventilation, timber frame construction. The house builder offers a standard air-water heat pump (NIBE or VIESSMANN). According to him, that is currently the most sensible option (gas with solar collectors almost the same price but old school, brine-water heat pump significantly more expensive and hardly pays off anymore at KFW55).

Now I read here that the price differences are not that high. However, I did not understand the calculation:

The subsidy is 35%, that would be 2,800€ on 8,000€ additional costs, not 4,000€, but whatever. What puts me off (with respect to our situation):
- high effort for drilling (permits)
- too small a plot for ring trench collector

So... air-water heat pump. I'm with the house manufacturer: with an annual performance factor of about 4.5 compared to 5.5 for a brine-water heat pump, I have 18% higher electricity costs per year with an air-water heat pump. With total costs around 1,000€ p.a., that is acceptable.

What bothers me more is the "rumor" that air-water heat pumps are prone to faults and have a short lifespan..... does anyone have experience?

I am less bothered by the outdoor unit. We also have a not-so-nice side of the house behind the carport, adjacent to the utility room.

My idea is: we get a (small sized) stove inside the house. With corresponding temperature sensors and actuators on the underfloor heating, I could bridge the harsh winter period. From the experience with the slow underfloor heating, we want a stove anyway.

I have read, 10cm instead of 15cm spacing for the underfloor heating. Does that really only cost a few hundred euros? How much is the gain in quality and reduction in flow temperature?

Regards, Andreas

Good questions. How was it with the ground collectors? Did you have restrictions due to these (no planting, etc.)?