ᐅ Room Ventilation for KfW 55 Apartment

Hello everyone,

like most of you, we are currently planning to buy our own home and therefore have ongoing questions about house/apartment construction. We want to purchase a top-floor apartment (4 rooms) built to KfW55 standard. The construction specifications for the room ventilation state the following:

"The supply air for room ventilation (outside air inlets) is provided through the window units. Exhaust air is removed by electric fans in the bathrooms, using both a basic ventilation mode and a demand-controlled ventilation mode. The kitchens do not have exhaust air, as this would interfere with the ventilation concept, so as part of the on-site kitchen planning, recirculation hoods may need to be considered."

I haven’t found much information online about this, except that this type of ventilation with outside air inlets in the window units is typically used in renovations where there is not enough space for a mechanical ventilation system. Currently, in our apartment, we have a decentralized ventilation system with heat recovery. Are these systems comparable? How do these types differ?

Thank you very much and best regards

This option sounds to me, as a layperson, like the cheapest possible solution. No ductwork, no control system as would be required for a central system. No communication between units, as would be necessary for a decentralized system with heat recovery. Just a wall penetration for the bathroom fan, a power connection, and an additional switch input for the bathroom fan—that’s it.

In exchange: heat recovery is eliminated. Humidity control is eliminated. Conditioning of the incoming outside air is eliminated—it will probably be very uncomfortable near the windows in winter when cold outside air has to be warmed simply by passing through the window frame...

Good morning and thank you for the response.
I had a similar thought but wasn’t entirely sure. To me, the term KFW55 still represents an energy-efficient building standard, which is why I am asking whether this type of ventilation might have advantages compared to a decentralized ventilation system.

Christian144 schrieb:
...We are planning to buy a top-floor apartment (4 rooms) with KFW55 standard....

It is usually worth taking a close look at the actual summer heat protection! Whenever I hear “top-floor apartment,” all my warning signals go off immediately!
If you experience problems, simply ask the seller for a contractually guaranteed maximum room temperature during the summer heat period. I am quite sure you won’t hear much from this seller afterwards.

Christian144 schrieb:
...I haven’t found much information about this online, ...

Are you sure that anonymous online opinions without any liability or professional qualifications are economically useful for your specific needs?
Sustainable value is certainly not obtained through anonymous internet opinions.
Professionals do not give away their knowledge for free; otherwise, they wouldn’t be able to do business!

Best regards.

Hello €uro,

thank you for your feedback. Of course, I understand that information from the internet is not 100% reliable, but usually you can get a general idea as well as some additional considerations. For a final and well-founded statement, I will have to consult a professional.

If there are problems, just ask the provider about a contractually guaranteed maximum RT during the summer heat period

what does Max. RT stand for?

Best regards and thanks

Hello,

Christian144 schrieb:

For me, the KFW55 standard still represents energy-efficient construction

In relation to what and for what investment?

Christian144 schrieb:

and therefore also the question whether this type of ventilation

Calling this a ventilation system, I find more than bold for this kind of setup

Regards, Bauexperte