ᐅ Is KfW 40+ achievable with a decentralized ventilation system?

Created on: 4 Dec 2019 08:00
S
Specki
Good morning,

I have a question that I couldn’t find a clear answer to on the internet. Maybe someone here knows for sure. For a KfW 40+ residential unit (it will be a multi-family building), is a central ventilation system mandatory, or is a decentralized ventilation system with heat recovery also acceptable?

I believe a decentralized system should be possible since KfW requires ventilation systems with at least 80% heat recovery efficiency, which some decentralized systems can achieve. However, I have also read in some places that a central system is mandatory.

Maybe you can provide more information on this. Thanks in advance.

Best regards,
Specki
B
Bookstar
4 Dec 2019 12:29
Whether allowed or not, I strongly advise you against installing a decentralized ventilation system.
G
guckuck2
4 Dec 2019 14:43
To have all opinions represented here:

- Ventilation IS a mandatory component for KfW 40+ buildings, as you yourself quoted.
- The same quote mentions "ventilation system with heat recovery," so there is no restriction to central or decentralized systems.
- In the same document, there are additional ventilation requirements in the free text. Also, the technical FAQ applies.
- You will need the KfW consultant anyway; ask them if the official documentation is not sufficient for you.
- Decentralized systems are significantly cheaper but include low-quality units that can cause trouble. Central systems are better. However, for apartment buildings, in my opinion, that is like casting pearls before swine.
K
Kardionaut
30 Jan 2020 17:37
I live in a two-family house, built in 2014, KfW 40 standard, with each residential unit equipped with a decentralized ventilation system.
So, decentralized ventilation cannot be considered a disqualifying factor for KfW 40.

Regards