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 So this argument is no longer valid.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
Bookstar schrieb:
Without the wood stove, I think my wife would have moved to a hotel many times by now 😀You just need to raise the supply temperature of the underfloor heating and not brag after the heating season about how little kWh the heat pump has "used." 😉H
hampshire31 Jul 2021 16:23@Acof1978 : When a non-smoker acknowledges that smoking is harmful, they make a valid point. This does not change even if the non-smoker uses cocaine. Burning split logs just for the appearance can be called a form of waste regardless of someone’s lifestyle—and from an objective viewpoint, that is correct. I don’t find it to be a big issue in this case.
A wood stove without a heat storage system has a very steep heating curve and is a fast-responding system. Underfloor heating, on the other hand, is a slow-responding system. Operating these two systems in parallel requires some attention, so I wouldn’t plan them separately, which is perfectly doable during new construction.
A wood stove without a heat storage system has a very steep heating curve and is a fast-responding system. Underfloor heating, on the other hand, is a slow-responding system. Operating these two systems in parallel requires some attention, so I wouldn’t plan them separately, which is perfectly doable during new construction.
hampshire schrieb:
@Acof1978: When a non-smoker points out that smoking is harmful, they have a valid point. That doesn't change just because this non-smoker uses cocaine. Burning firewood solely for the appearance can be considered a form of waste by anyone, regardless of their lifestyle—and objectively, they would be right.
I don’t find it too problematic in this case.
A wood stove without a heat storage tank has a very steep heating curve and is a fast-responding system. A radiant floor heating system is slow to respond. Running these two systems in parallel requires some attention; that’s why I wouldn’t plan it separately, which is easily done in a new build.You are probably right. But this is how it is with us. In this case, it’s not ecological. However, it was a conscious decision. We don’t want to use the fireplace for heating, and for the few days (I estimate about 20) a year we operate it, it doesn’t make sense for us to also use it to heat the house.
You are, of course, also correct about the ecological footprint.
For this one thing, we made a deliberate choice, just like with our rainwater harvesting system and photovoltaic panels. It’s a trade-off. A job e-bike will be coming soon, too, which will reduce our car trips.
Acof1978 schrieb:
Despite everything, it would be more environmentally sensible to build a multi-family apartment building there rather than a single-family home. People can justify anything, but single-family houses are always less eco-friendly than apartment buildings when built the same way. Apart from the fact that the old house will never be as energy-efficient as a new build.
As I already said: glass house and stones... Sustainability is what matters environmentally. The old building already has a carbon footprint. Increasing it with a multi-family building makes no sense. Only if those moving into the apartment building would otherwise have all built single-family homes would it be justifiable.
Simplifying complex issues and selling them here with rhetorical tricks, in my opinion, does not belong in this forum.
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