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?
No circulation pump for 190 sqm (2,045 sq ft). However, the main bathroom is located directly above the utility room.
The hot water reaches the bathrooms very quickly and doesn’t run cold like it did in the old apartment. It takes a bit longer in the kitchen, but that’s not a problem since the sink is large.
Is the KFW loan still worth it?
Are you planning to sell the house within the next 10-15 years?
If the answer to both is no,
I would go with gas and controlled ventilation now,
and possibly add solar or photovoltaic panels and a heat pump later.
The hot water reaches the bathrooms very quickly and doesn’t run cold like it did in the old apartment. It takes a bit longer in the kitchen, but that’s not a problem since the sink is large.
Is the KFW loan still worth it?
Are you planning to sell the house within the next 10-15 years?
If the answer to both is no,
I would go with gas and controlled ventilation now,
and possibly add solar or photovoltaic panels and a heat pump later.
KfW 55 would only be considered as an emergency solution; we generally prefer funding through the ISB Bank of Rhineland-Palatinate.
Selling the house only comes into consideration if it becomes necessary for health reasons. In principle, the plan is to stay in the house as long as possible—until we are carried out feet first by the undertaker.
We would provide for a conduit or empty pipes for a future solar or photovoltaic system.
Or later, when the gas condensing boiler is old enough or breaks down, we would switch to a heat pump. These will likely not become more expensive or less efficient over time... and they might still be eligible for funding.
Selling the house only comes into consideration if it becomes necessary for health reasons. In principle, the plan is to stay in the house as long as possible—until we are carried out feet first by the undertaker.
We would provide for a conduit or empty pipes for a future solar or photovoltaic system.
Or later, when the gas condensing boiler is old enough or breaks down, we would switch to a heat pump. These will likely not become more expensive or less efficient over time... and they might still be eligible for funding.
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