KfW 55 - Ventilation system yes/no? - Experiences

Are you building with a heat pump? If yes, do you get a seasonal performance factor of 4.5 or higher? If yes, apply for BAFA together with a controlled residential ventilation system (must be jointly regulated, e.g. via radio), then you get 35% funding on the systems. That almost covers the costs for the controlled residential ventilation.

I don't know the seasonal performance factor of our heat pump, but we definitely get the 35% funding (without ventilation). Do you think we would also get 35% on the central ventilation system then? That would of course make things more interesting again....

Otherwise, what does the energy consultant say about the KFW55 building without controlled residential ventilation? Decentralized solutions always mean that you bring the fan noise into the room and the heat recovery is zero or very close to zero. But especially if you are fans of fresh air, I would consider taking on the costs for controlled residential ventilation.

I haven’t talked to the energy consultant about the ventilation system yet, only with the building advisor so far. He says that with the general contractor, no building has ever started to mold, whether with ventilation or without. I mean, he could also say something else to sell something...

Possibly in the East also simply as it is often seen here, that they do not know how to build it well and suitable for the calculation program. What is better for a general contractor: a controlled residential ventilation system that causes complaints or one that is not present and thus causes no problems due to lack of planning? Our completely independent energy consultant absolutely recommended doing it because an average household cannot ventilate as required in modern buildings.

I don't know the annual performance factor of our heat pump, but we definitely get the 35% subsidy (without ventilation). Do you think we would also get 35% for the central ventilation system? That would of course make the thing more interesting again....

Have the general contractor put in writing that the heating installation meets the requirements for BAFA funding, preferably with the confirmed BAFA application. Controlled residential ventilation has recently become eligible for funding if the heat pump is funded. However, controlled residential ventilation and the heat pump must then be able to be controlled together, e.g. via an overarching control unit like with Nibe or via Smart Home (KNX, radio, ...). There are various information sheets from Nibe, Zehnder, Maico, and of course the official BAFA information sheet.

I haven't talked to the energy consultant about the ventilation system yet, only with the construction advisor so far.

You should do that. Ours expressed concerns right at the beginning that we wouldn't meet the KFW standard if we built without controlled residential ventilation. Our builder, on the other hand, told us that controlled residential ventilation wasn't needed. It's always different perspectives.

For us, building with KfW 70 and without controlled residential ventilation is not even a consideration. The repayment subsidies on both sides are simply so attractive compared to the price that you really have no other choice.

The price you mention is completely exaggerated.

What we also plan to do: we will most likely take the heating/ventilation trade out independently and contract it externally, as we do not feel well taken care of by the construction companies in these cases. This way, you just go to a heating engineer/air conditioning company and ask for a quote and will probably save quite a bit in this case.

For us, there are specified additional costs for KfW 55 that, depending on the provider, lie between 5k and 8k (additional insulation, etc.). Otherwise, the house is not even 1% different than if we built it with KfW 70. Repayment subsidy 18k, so you can calculate for yourself what you pay.

In addition, there is the BAFA subsidy for air-water heat pumps and controlled residential ventilation of 35%... So, as I said, for us there is purely mathematically no other option than to take this on, whether you want to or not.

For us, it's not about the question of KfW70 or KfW55, but about the question of KfW55 with or without ventilation.

For us, it's not a question of KfW70 or KfW55, but rather KfW55 with or without ventilation.

Oh, sorry, I somehow had something else in mind when I read through everything here Then I would still go for the ventilation and possibly then outsource the whole heating/ventilation topic separately, as I already mentioned. A cooling-climate operation will get you the central system for 12k flat.