ᐅ Energy Saving Regulation 2016 without Active Ventilation and Exhaust Systems

Hello everyone,
we have received an offer from a developer for a terraced house. It states that the building will comply with the energy standard of the Energy Saving Ordinance 2016 (EnEV 2016), which I understand is somewhat less efficient than KfW 70. According to the requirements, a thermal building envelope will of course be created. A passive ventilation system is planned (through micro-slits in the windows). This passive ventilation is considered sufficient when the house is unoccupied; otherwise, manual ventilation is required.

My question:
Is passive ventilation and the omission of an active ventilation system still considered state of the art nowadays? Are houses still frequently built this way?

Thank you in advance for your feedback.
Stefan

Yes, it is common and feasible. I would just recommend planning for an exhaust fan, for example in the bathroom. This ensures a controlled airflow through the house—from the gaps in the windows or walls in, and out through the fan. Our house is built this way, and it works well. Still, airing out the house properly once a day is essential. We do this regularly. Karsten

After spending a lot of time researching this, here is what I can tell you:

A mechanical ventilation system is usually not necessary for most buildings, unless the builder requires it to meet certification standards such as KFW. For a house built according to energy-saving regulations, you can manage without a system if you consistently perform the required manual ventilation, either by opening windows or using the passive ventilation in the windows you mentioned.

A mechanical ventilation system is convenient and can make life easier, but it is generally not absolutely necessary.

We currently have a decentralized mechanical ventilation system and are now installing a central system in our new build, mainly because we are not the most consistent ventilators in the world.

I would recommend investing in one, as few people ventilate sufficiently, and it is very comfortable. Looking to the future, there will likely be very few new builds without such a system.

Best regards

Steffen

From my own experience, I can tell you that water tends to accumulate in those slots in the window. I think it is probably condensation. I can’t say whether it is a serious issue or not, only that I have often seen water there. We are currently renting a newly built apartment, so the windows are quite new. Even when I spoke to the general contractor, he advised against using slots in the window, as he had also heard of related problems.

An alternative to central or decentralized ventilation could be ventilation through the roller shutter box.

We are not building according to KfW standards, but according to the Energy Saving Ordinance, ventilation solely by opening windows is not sufficient.

We only use the Air window ventilation system. We have condensation in the bedroom, which collects on the shutters and causes the slats to freeze, but otherwise there are no problems. The humidity level in winter is around 40% even without excessive ventilation.

The only downside is the constant airflow around the ventilation area.

It’s probably not the latest technology, and sometimes airtight seals around the windows are reopened, which is a bit ironic with windows having low U-values and then gaps like these appearing.

Long story short, I wouldn’t do it differently in the next house.