Hello everyone. My partner and I are planning to build a house. About 140-150 square meters (1507-1615 square feet), 1.5 stories. After initially considering building a KfW 40 house, I quickly moved away from that idea. The general opinion seems to be that it’s not cost-effective (considering only the costs). So now we want to build according to KfW 55 standards.
Underfloor heating is planned throughout the entire house. However, despite extensive research, we are still uncertain about other details. For the standard KfW 55, a heat pump or a gas connection (then with a share of renewable energy) is mandatory, right?
What do you think is the best combination for KfW 55? I had originally planned on a ground source heat pump / geothermal system. But this seems somewhat oversized for a new build, doesn’t it? What technology would you recommend for an air-source heat pump?
Does it make sense to install a photovoltaic system (because of the additional electricity costs of the heat pump and generally) or solar thermal collectors? Would solar thermal still be mandatory if using a heat pump? With gas, solar thermal would be mandatory, right?
I’m also interested in your opinions on a controlled mechanical ventilation system. If yes, with or without heat recovery? I know the cost of the system does not pay off financially. But it’s a gain in comfort (no need to ventilate manually and you have fresh air). Does it offer any additional benefits? The filters would also reduce dirt like pollen, dust, etc. inside the house, right? Maybe someone has current experiences with these systems. I have read a lot, but mostly reports from 3-4 years ago.
Am I forgetting any important systems or options?
Underfloor heating is planned throughout the entire house. However, despite extensive research, we are still uncertain about other details. For the standard KfW 55, a heat pump or a gas connection (then with a share of renewable energy) is mandatory, right?
What do you think is the best combination for KfW 55? I had originally planned on a ground source heat pump / geothermal system. But this seems somewhat oversized for a new build, doesn’t it? What technology would you recommend for an air-source heat pump?
Does it make sense to install a photovoltaic system (because of the additional electricity costs of the heat pump and generally) or solar thermal collectors? Would solar thermal still be mandatory if using a heat pump? With gas, solar thermal would be mandatory, right?
I’m also interested in your opinions on a controlled mechanical ventilation system. If yes, with or without heat recovery? I know the cost of the system does not pay off financially. But it’s a gain in comfort (no need to ventilate manually and you have fresh air). Does it offer any additional benefits? The filters would also reduce dirt like pollen, dust, etc. inside the house, right? Maybe someone has current experiences with these systems. I have read a lot, but mostly reports from 3-4 years ago.
Am I forgetting any important systems or options?
Is it actually clear which type of construction the original poster wants to build? I mean, with a timber frame construction, you often already meet KfW55 standards. That was the case for us—the additional cost for KfW40 was manageable and gave me a better feeling, even though the energy savings compared to KfW55 will be small. But we also had a higher repayment subsidy.
D
Deliverer7 Jun 2018 10:04Tom1607 schrieb:
In winter, I basically heat with electricity, and all the wishful thinking from air-to-water heat pump enthusiasts doesn’t change that!!I believe all owners of air-to-water heat pumps are aware of this fact. However, I don’t understand why this should be considered a problem...
Deliverer schrieb:
I believe all owners of air-to-water heat pumps are aware of this fact. However, I don’t see why that should be a problem...I didn’t say it was a problem. It’s just more expensive than gas because 1 kW of heat from electricity costs about 30 cents, while 1 kW of heat from gas is around 6 cents. Since the air-to-water heat pump is also more expensive to install, this should be taken into account. That’s all I wanted to say—nothing more, nothing less.
Thank you for all the suggestions, tips, and advice so far.
The construction method is still not entirely clear. As it often happens, about a year ago I was in favor of a prefabricated house, and my partner was against it. Like a bad soap opera, today it is exactly the opposite. Indoor soundproofing, the load-bearing capacity of walls regarding shelves, as well as fire and water protection, are causing me concerns with a prefabricated house.
I think a ventilation system might be a viable option after all. I found an excellent comparison online on the Inventer website that covers all aspects. There, the decentralized ventilation system comes out as the winner. Do you have any objections to this?
The construction method is still not entirely clear. As it often happens, about a year ago I was in favor of a prefabricated house, and my partner was against it. Like a bad soap opera, today it is exactly the opposite. Indoor soundproofing, the load-bearing capacity of walls regarding shelves, as well as fire and water protection, are causing me concerns with a prefabricated house.
I think a ventilation system might be a viable option after all. I found an excellent comparison online on the Inventer website that covers all aspects. There, the decentralized ventilation system comes out as the winner. Do you have any objections to this?
D
Deliverer7 Jun 2018 12:50Tom1607 schrieb:
I never said it was bad. It’s just more expensive than gas because 1 kW of heat generated by electricity costs around 30 cents, while 1 kW of heat from gas is about 6 cents. Since air-to-water heat pumps are also more expensive to install, this should be taken into account. That’s all I wanted to say, no more and no less.Yes. Of course, gas is cheaper per kW.
But you also have to consider the costs for connection (or tank), the chimney, and its cleaning. It should also be noted that in new buildings, only a small amount of the mentioned kilowatts is actually needed. So the financial impact nowadays is relatively small (in the range of a few hundred dollars per year).
Furthermore, there is reliance on two energy sources as well as on foreign countries. The option for self-supply is never available. If the underfloor heating is incorrectly designed, switching to electric heating later is not possible.
All of this must be taken into consideration—no more, no less.
Tx-25 schrieb:
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I think a ventilation system might actually be the right solution. I found an excellent comparison on the website inventer that takes all factors into account. According to it, the decentralized ventilation system comes out on top. Do any of you have objections to this?cool. So the manufacturer of decentralized ventilation systems thinks decentralized systems are better than centralized ones?
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