ᐅ Decentralized ventilation only in individual rooms for new construction to KfW 55 standard?

Lumpi_LE schrieb:

Quite nonsense. On what grounds?

I was just about to say exactly the same...

-Maintenance
-Cleaning
-Investment costs
-Limited savings potential (investment is hardly recovered through saved heating costs)
-Prone to defects / replacement needed after X years
-A possible source of bacteria / mold (if not cleaned regularly)

The only advantage would have been comfort and protection against mold (for us). Although the latter is not necessary (according to the general contractor).
Given our tight budget, it was not worth it for us.

Controlled residential ventilation is like VACCINATING home builders.

That's where exactly these confusing statements come from.

FoxMulder24 schrieb:

We are building a KfW55 house (this year) without mechanical ventilation with heat recovery. So it is possible.
For us, it was a cost issue (easily around €12,000).

Our wall construction (timber frame prefabricated building) meets the KfW40 insulation standards (already standard with our general contractor).
Therefore, mechanical ventilation with heat recovery is not necessary. The KfW application was approved without any problems.
Only in the bathroom will we install a decentralized unit. Why? Because that’s where the shower is, the washing machine/dryer are located, and laundry is hung there. To be on the safe side, we’re putting a unit in.

Interestingly, every salesperson (house manufacturer) advised us against mechanical ventilation with heat recovery. Also an engineer in the family.
Apparently, the majority of houses today are again sold without mechanical ventilation with heat recovery (according to statements from two manufacturers). I can’t judge if that’s true. I was surprised by it myself.

Now honestly, who has installed mechanical ventilation with heat recovery—whether central or decentralized—just because of the KfW subsidy? Apart from those who want the higher subsidy now, everyone else has it for comfort or fear of mold. For me, it’s the latter. We simply cannot ventilate enough to prevent such problems. We previously had a fully renovated apartment with external thermal insulation composite system (ETICS). From the first year on, there was mold growth even though, from our perspective, we ventilated frequently and properly, meaning fully opening windows rather than tilting them.

FoxMulder24 schrieb:

-Maintenance
-Cleaning
-Investment costs
-Limited savings potential (hardly recouped through reduced heating costs)
-Prone to faults / replacement after X years
-Potential source of bacteria / mold (if not cleaned regularly)

The only advantage would have been comfort and protection against mold (for us). Although the latter is not necessary (according to the general contractor).
So, it wasn’t worth it to us within our tight budget.

As for the “not necessary” part, that’s what your general contractor says; he must have his reasons for wanting to avoid the effort. Whether it’s beneficial to leave it out will become clear afterward. See my last comment.

FoxMulder24 schrieb:

-Maintenance
-Cleaning
-Investment costs
-Limited savings potential (hardly recovers investment through saved heating costs)
-Prone to faults / replacement needed after X years
-Potential source of bacteria / mold (if not cleaned regularly)

This also applies to windows, but it still makes sense to have them. However, everyone has to decide that for themselves.