ᐅ Is a brine-to-water heat pump still worthwhile for a KfW 40+ energy standard building?
Created on: 6 Dec 2021 10:36
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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
H
hampshire6 Dec 2021 13:03The drilling costs are completely unclear. However, they are crucial for any calculation.
One aspect could also be that you don’t want to have those annoying split parts lying around somewhere.
What about the service life? Faster payback and quicker failure does not necessarily mean a cheaper solution.
One aspect could also be that you don’t want to have those annoying split parts lying around somewhere.
What about the service life? Faster payback and quicker failure does not necessarily mean a cheaper solution.
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009_frank6 Dec 2021 13:09Thank you for your responses. The drilling is estimated to cost around 10,000–13,000 euros. A coaxial trench collector might be an alternative. Unfortunately, I cannot comment on the lifespan. Perhaps air-source heat pumps tend to "break down" more often?
H
hampshire6 Dec 2021 13:21Question for the experts:
I have always understood efficiency calculations to assume optimal operating conditions. Now, the air-to-water heat pump loses efficiency as the outdoor temperature drops, while the ground-source heat pump conditions remain relatively constant. How is this factored into energy cost calculations?
I believe that in areas with frequent frost, a ground-source heat pump will perform significantly better in terms of energy consumption despite higher installation costs—perhaps this is why they are quite common in Switzerland...
I have always understood efficiency calculations to assume optimal operating conditions. Now, the air-to-water heat pump loses efficiency as the outdoor temperature drops, while the ground-source heat pump conditions remain relatively constant. How is this factored into energy cost calculations?
I believe that in areas with frequent frost, a ground-source heat pump will perform significantly better in terms of energy consumption despite higher installation costs—perhaps this is why they are quite common in Switzerland...
O
Oetzberger6 Dec 2021 13:29hampshire schrieb:
How is this taken into account in the calculation of operating costs?The temperature is factored into the annual performance factor calculator. Broadly speaking, you are correct: the colder the standard and the higher the building’s heating energy demand, the greater the advantage of ground-source heat.The original poster would be better off investing their money in a properly designed underfloor heating system and wall heating in the bathroom. If using ground-source, then with a horizontal trench collector.
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009_frank6 Dec 2021 13:40Oetzberger schrieb:
The temperature is taken into account in the annual performance factor calculator. Roughly speaking, you are right: the colder the standard and the higher the building’s heating energy demand, the greater the benefit of using ground source heat.
The original poster should rather invest their money in a properly designed underfloor heating system and a wall heating system in the bathroom. If going with ground source heat, then with a horizontal ground heat exchanger (trench collector).Thank you. I live in the Eifel region at an elevation of 496m (1,627 feet). It can get quite cold in winter sometimes 😉 but temperatures below -5°C (23°F) are very, very rare here as well.
R
RotorMotor6 Dec 2021 14:00The main argument for a ground-source heat pump (brine-water heat pump) is actually that you can’t find a suitable location for an air-source heat pump. ;-)
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