Hello everyone
We are currently taking the next steps toward building our own home. We have looked at several prefabricated houses and spoken with sales consultants from various providers. Based on this, we have created a top 5 list. Now I want to contact these 5 companies with our floor plan and the standards we want. This way, I hope the list will be reduced by 2-3 providers after receiving the first offers.
In my inquiry, I want to roughly outline what we have in mind. KFW55, KFW40, or KFW40+ is not yet very important—it will be one of these standards. Our floor plan does not differ much from the standard layouts offered by prefab house suppliers. Something like a simple 8x10 meter (26x33 feet) rectangular shape... To be able to compare the 5 offers reasonably, I want them all to be as similar as possible. Therefore, I would like to specify the heating system.
Now the question is, what is the right choice… I assume this is partly a matter of philosophy? The options are an air-to-water heat pump, an air-to-air heat pump, or a ground-source (geothermal) heat pump. I assume most have one of these three systems combined with solar panels on the roof.
My first thought was this: an air-to-air heat pump, since we would also have an automatic ventilation system in the house, making manual airing less or unnecessary. However, I have learned that all KFW-certified houses are so well insulated that they almost always have automatic ventilation. So this argument is no longer valid. Nevertheless, I still find the air-to-air heat pump interesting. We also want to install a wood stove in the living room. With an air-to-air heat pump, the indoor air is circulated throughout the house, so I could benefit from the wood stove’s heat everywhere, right? Perhaps even with heat recovery, which is usually included.
Another advantage of the air-to-air heat pump would be that if it ever gets too warm, we could install a fixed air conditioning unit somewhere in the house, and the whole house would benefit. The built-in cooling systems in these heat pumps usually aren’t as effective as promised.
Is it true that an air-to-air heat pump cannot provide domestic hot water? Then a second system would be needed just for hot water, which means more costs, two systems to maintain, and more space taken up. In the forum, I mostly see air-to-water heat pumps mentioned, probably combined with underfloor heating. That seems to be the most popular system. Is there a particular reason for this?
Geothermal heating combined with a heat pump seems to be the most efficient. But then I would also have underfloor heating, right? We actually didn’t want underfloor heating, but as I’m writing this, I’m starting to convince myself toward geothermal or air-to-water heat pumps…
How did you make your decision and why? Somehow, I don’t fully trust the salespeople, since they want to sell what makes more money, right? And since I’m not very technical in this area, I’m hoping to benefit from your experience.
Best regards Andreas_79
We are currently taking the next steps toward building our own home. We have looked at several prefabricated houses and spoken with sales consultants from various providers. Based on this, we have created a top 5 list. Now I want to contact these 5 companies with our floor plan and the standards we want. This way, I hope the list will be reduced by 2-3 providers after receiving the first offers.
In my inquiry, I want to roughly outline what we have in mind. KFW55, KFW40, or KFW40+ is not yet very important—it will be one of these standards. Our floor plan does not differ much from the standard layouts offered by prefab house suppliers. Something like a simple 8x10 meter (26x33 feet) rectangular shape... To be able to compare the 5 offers reasonably, I want them all to be as similar as possible. Therefore, I would like to specify the heating system.
Now the question is, what is the right choice… I assume this is partly a matter of philosophy? The options are an air-to-water heat pump, an air-to-air heat pump, or a ground-source (geothermal) heat pump. I assume most have one of these three systems combined with solar panels on the roof.
My first thought was this: an air-to-air heat pump, since we would also have an automatic ventilation system in the house, making manual airing less or unnecessary. However, I have learned that all KFW-certified houses are so well insulated that they almost always have automatic ventilation. So this argument is no longer valid. Nevertheless, I still find the air-to-air heat pump interesting. We also want to install a wood stove in the living room. With an air-to-air heat pump, the indoor air is circulated throughout the house, so I could benefit from the wood stove’s heat everywhere, right? Perhaps even with heat recovery, which is usually included.
Another advantage of the air-to-air heat pump would be that if it ever gets too warm, we could install a fixed air conditioning unit somewhere in the house, and the whole house would benefit. The built-in cooling systems in these heat pumps usually aren’t as effective as promised.
Is it true that an air-to-air heat pump cannot provide domestic hot water? Then a second system would be needed just for hot water, which means more costs, two systems to maintain, and more space taken up. In the forum, I mostly see air-to-water heat pumps mentioned, probably combined with underfloor heating. That seems to be the most popular system. Is there a particular reason for this?
Geothermal heating combined with a heat pump seems to be the most efficient. But then I would also have underfloor heating, right? We actually didn’t want underfloor heating, but as I’m writing this, I’m starting to convince myself toward geothermal or air-to-water heat pumps…
How did you make your decision and why? Somehow, I don’t fully trust the salespeople, since they want to sell what makes more money, right? And since I’m not very technical in this area, I’m hoping to benefit from your experience.
Best regards Andreas_79
Andreas_79 schrieb:
In my inquiry, I want to roughly outline what we have in mind. KFW55, KFW40, or KFW40+ is not that important right now; it will be one of these.. I have completely abandoned the KFW concept. I don’t believe in sealing a house tightly with insulation. Good masonry provides excellent thermal insulation without “sealing” the house. That’s why I also left out a ventilation system since we open the windows twice a day anyway. A wood stove combined with a ventilation system is even more complex and something I would never do. In my opinion, KFW standards lead to overly complex, expensive, and sometimes illogical solutions, while the energy savings are minimal. (You are welcome to debate this here, but it won’t change my opinion.) The KFW loans don’t really make much sense either.
An air-to-water heat pump, an air-to-air heat pump, or a geothermal water heat pump are options worth considering. Here in Bavaria, the bureaucratic hurdles and regulations are so extreme that air-to-water or geothermal heat pumps are generally not worth it. With an air-to-air heat pump, you can easily heat and supply hot water for a single-family house of 200 m² (2,150 ft²). If you also use a wood stove, it’s no problem at all. Moreover, an air-to-air heat pump is vastly cheaper. Especially when combined with a photovoltaic system, it is the preferred solution.
Is there a reason why you don’t want underfloor heating? It is the most efficient and comfortable option, which is why it is now installed almost everywhere.
P.S.: I deliberately decided against a wood stove because it involves too much dirt and effort for me. If I wanted the cozy effect, I would rather install a high-quality gas fireplace.
sub-xero schrieb:
Here in Bavaria, the bureaucratic obstacles and regulations are so extreme that air-to-water heat pumps or geothermal heat pumps are hardly worthwhile. You can easily heat a single-family home of 200 m² (2,150 sq ft) and supply hot water with an air-to-air heat pump. If you also use a wood stove, it’s not an issue at all. Besides, an air-to-air heat pump is much more affordable. Especially in combination with a photovoltaic system, it is the preferred solution. I made a typo. I use an air-to-water heat pump. I consider groundwater heat pumps or geothermal heat pumps too expensive and unnecessary. I would also not use an air-to-air heat pump.
R
RotorMotor5 Aug 2021 07:12A rather confusing post due to misunderstandings.
H
hampshire5 Aug 2021 08:45RotorMotor schrieb:
Wood always releases the same amount of C(O2) that it absorbed while growing.rdwlnts schrieb:
The same applies to coal as well.Regarding the environment, the timescale is important. If you release too much CO2 from long-term storage back into the system in a short period, the risk of system overload is high. If you have a cycle of a few hundred years in which CO2 is absorbed and released without reducing the overall CO2 storage, you have a balanced carbon cycle. That is the difference between wood and coal. The CO2 behaves the same way regardless of its source.sub-xero schrieb:
I have completely abandoned the KFW concept.We have as well—not because we wanted a drafty house, but because we disagreed with the requirements tied to the funds for an energy-efficient and comfortable home as we see it. The technical complexity of the building systems and the resulting feeling of dependency played a role, as did our preference for radiant heating sources in winter and living with open windows whenever heating is not needed.sub-xero schrieb:
since we open the windows twice a day anyway.Isn’t that quite frequent for manual ventilation?Similar topics