ᐅ Is a brine-to-water heat pump still worthwhile for a KfW 40+ energy standard building?
Created on: 6 Dec 2021 10:36
0
009_frank
Hello everyone,
We are planning a prefabricated house built to KfW 40+ standard, including two residential units of 95 m² (1,023 sq ft) each. One of these units will be rented out. Unfortunately, four different suppliers have given us four different opinions regarding the heating system. Some say that a ground-source heat pump (brine-to-water) is not worthwhile because of the drilling and costs, especially since we also have ventilation systems with heat recovery, so an air-to-water heat pump would be completely sufficient. Whether to choose a monoblock or split system is also debated among the suppliers. As a layperson, it’s quite confusing.
What is your opinion on this?
Best regards
We are planning a prefabricated house built to KfW 40+ standard, including two residential units of 95 m² (1,023 sq ft) each. One of these units will be rented out. Unfortunately, four different suppliers have given us four different opinions regarding the heating system. Some say that a ground-source heat pump (brine-to-water) is not worthwhile because of the drilling and costs, especially since we also have ventilation systems with heat recovery, so an air-to-water heat pump would be completely sufficient. Whether to choose a monoblock or split system is also debated among the suppliers. As a layperson, it’s quite confusing.
What is your opinion on this?
Best regards
B
Benutzer2006 Dec 2021 15:14RotorMotor schrieb:
The main reason to choose a ground-source heat pump is basically that you can’t find a suitable location for an air-to-water heat pump. ;-) If necessary, indoor installation is an option. Basically with supply and exhaust air like in controlled residential ventilation. A suitable location for an air-to-water heat pump is (almost) never lacking.
Benutzer200 schrieb:
My personal opinion: Ground-source heat pumps are not worthwhile anymore starting from KfW40 standard. The additional cost will never be recovered through lower heating expenses.
Example: 150m² (1,615 sq ft) house: heating costs with air-source heat pump €600, with ground-source heat pump 20% better = €480.
The extra cost from air-source to ground-source heat pump is €6,000 (?), resulting in a payback period of 50 years.
It’s all easy to estimate roughly.
If renting out, definitely choose air-source heat pump, see post by [USER=9254]@haydee However, this calculation is very simplified. You assume that electricity prices remain constant. How likely is that? The higher the electricity costs, the greater the savings...
R
RotorMotor6 Dec 2021 16:17Benutzer200 schrieb:
If necessary, indoor installation is possible. Basically with supply and exhaust air like in a mechanical ventilation with heat recovery system. At the location, air will (almost) never be in short supply for an air-to-water heat pump. There may be solutions, but indoors would not have been an option for us.
Fortunately, we found a spot outside.
If there had been a terrace or entrance there, I would have preferred to invest in a brine-to-water heat pump.
Tom1978 schrieb:
The calculation is very simplified, though. You assume that electricity costs remain constant. How likely is that? The higher the electricity costs, the greater the savings... Nobody has a crystal ball, but then you would also have to take into account the interest on the drilling costs.
And there are many options for that: simple loan, stocks, real estate, ...
Which initially makes a brine-to-water heat pump financially less attractive.
But there are few reasons why electricity should become significantly more expensive.
Electricity from wind or solar currently costs only about 3-8 cents/kWh to produce.
RotorMotor schrieb:
There are hardly any reasons why electricity should become significantly more expensive.
Electricity from wind or solar currently costs only about 3–8 cents per kWh to produce. Try telling that to those who sell it. 😀
RotorMotor schrieb:
No one has glass beads, but then of course you would also have to factor in the interest on the drilling costs.
There are many options for that: a simple loan, stocks, real estate, and so on.
Which initially makes a brine-water heat pump less financially attractive.
However, there are few reasons why electricity should become significantly more expensive.
Electricity generated from wind or solar currently costs only about 3-8 cents/kWh to produce. Why is the expensive option of deep drilling always talked about? Surface collectors did not cost more than an air-to-water heat pump in our case. I think they normally cost less than half as much as deep drilling. However, you do need a larger plot of land for them…
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RotorMotor6 Dec 2021 16:54Tom1978 schrieb:
Why is it that people always talk about the expensive option of deep drilling? But for that, you need a larger plot of land... That’s already an answer in itself. ;-)
But there are more reasons.
For example, my impression is that horizontal collectors are only offered by a few companies.
DIY installation is also not an option for everyone.
Basically, though, it is a good option that should be considered more often.
Tom1978 schrieb:
Horizontal collectors didn’t cost us more compared to an air-to-water heat pump. I think they usually cost less than half as much as deep drilling. Wait, no extra cost or half the extra cost?
How was the collector installed at your place?
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