Controlled residential ventilation - Yes or No?!

@ Construction expert - you write:

. Detached house built with ETICS => Mold formation. Or then, when both partners are engaged in regular work all day; especially at the time when the house has just been handed over, regulated ventilation is the "A" and "O," so it enjoys top priority, regardless of the construction system.

Is it indeed independent of the construction system? We are planning a solid wood new build and hear that the air in such tends to be too dry and sometimes air humidification should be considered.
A ventilation system is still under consideration for ecological, comfort-related, and health reasons. Although such a large investment should of course be well thought out. Good indoor climate could also be created through clay plaster; sufficient fresh air must of course be supplied regardless.

I would also be very interested in an answer here:
Background of my question. If you have planned a wood stove, this room usually cannot be connected to a central ventilation system anyway.

Why?

Hello Carola,

@ Bauexperte - you write:

Single-family house built with ETICS => mold growth. Or then, when both partners work full-time in a regulated job; especially at the time when the house has just been handed over, regulated ventilation is the "A" and "O", so it enjoys top priority, regardless of the construction system.

Is it indeed independent of the construction system? We are planning a solid wood new build and hear that the air in such tends to be too dry and that humidification should partly be considered. A ventilation system is still in the room for ecological, comfort-related and health reasons. Although such a large investment should of course be well considered. Good indoor climate could also be created with clay plaster; sufficient fresh air must of course be supplied independently of that.

Where ETICS is applied, I consider it a fatal mistake to forego ventilation (whether decentralized or centralized) and instead, for example, to give preference to a new kitchen.

The Energy Saving Ordinance 2009 - and probably the Energy Saving Ordinance 2012 again by 30% - simply put prescribes how much heat loss a house may have. It is initially logical that most providers try to realize this as cost-effectively as possible, and that is mostly ETICS. If you now build with aerated concrete, Poroton, pumice, or sand-lime brick with mineral exterior plaster - all of which to a certain extent allow "transport" of moisture - the problem of mold growth with analogous ventilation is largely negligible (I will leave aside for now that sand-lime brick and pumice do not manage without ETICS anyway). But if you apply ETICS, diffusion stops at the latest where the ETICS meets the masonry, the synthetic resin plaster (to stabilize the ETICS) adds its part. The moisture inside the house must go somewhere - added to this is that every person, if I remember correctly, produces 3.0 l/day of moisture by breathing.

If you build a prefab house, you somehow live in a plastic film anyway, since the system-related vapor barrier does not allow diffusion - but your bathroom/kitchen vapors and your breath want to go somewhere.

That means: for prefab houses and solid houses with ETICS, measures must be taken to transport moisture, otherwise you have an increased risk of mold in each room at the coldest spot of the exterior wall!

I cannot understand your statement that ventilation is an ecologically sensible system. It is certainly a comfort gain and also beneficial to health. Whether clay plaster is really beneficial for indoor climate, I cannot answer, as I have not dealt with it sufficiently. But I could imagine that entire clay walls might be more suitable there.

I would also be very interested in an answer here:
Background of my question. If you have planned a wood stove, usually this room cannot be integrated into a central ventilation system. Why?

That would also interest me greatly.

Kind regards

...Yes, we are planning a room-air-independent wood stove in the living room. If I understand correctly, the stove is supposed to receive the supply air via the chimney.

I would think about that again!

...By the way, my boyfriend is not yet convinced by the "cost-benefit calculation" of a controlled residential ventilation system. He would rather invest the money more "sensibly" and continue to ventilate manually as before. I tend more towards a controlled residential ventilation system, but without heat recovery - that would exceed the budget.

I would also think about this again! Either a controlled residential ventilation system with heat recovery or not at all!

...If a controlled residential ventilation system cannot be planned in the living room - wouldn't a decentralized solution be more sensible then? How can you ventilate the living room at all (other than manually)?

If the living room, as the traditional supply air room of a controlled residential ventilation system, is the installation room, then as a result of overpressure or balanced pressure, the installation of a certified, approved, room-air-independent stove/wood stove should not be a problem at all!

Best regards.

...Where an ETICS is applied, I consider it a fatal mistake to forgo ventilation (whether decentralized or centralized) and instead, for example, to prefer a new kitchen.

... , the synthetic resin plaster (to stabilize the ETICS) does its part. But the moisture inside the house has to go somewhere – in addition, if I remember correctly, every person produces 3.0 l/day of moisture through breathing.

Yes, the moisture has to go somewhere!

...If you build a prefabricated house, you more or less live in a plastic bag anyway, since the system-related vapor barrier does not allow diffusion – but your bathroom/kitchen vapors and your breath want to go somewhere.

That's right, moisture-regulating, -buffering interior plasters are usually missing in prefabricated houses!

We know the problem as well. Our house is from the 1950s and was insulated this year and had new sealed windows installed. Now I constantly have damp window panes that I can no longer dry with the morning ventilation. Even when the heating is barely on, the windows fog up and it hasn't even been that cold outside so far. I'm curious about the winter.

This is also a reason why I want to build something new.

Hello,

There are also plenty of people who find a controlled residential ventilation system rather unpleasant.

Rather rarely....

And that a building with ETICS "breathes" worse than without, I also do not consider correct, since a wall actually does not "breathe" at all.

To prevent water vapor condensation in multilayer components, the thermal resistance should increase from inside to outside (thermal insulation layer outside) and the vapor diffusion resistances should decrease. These conditions are met, for example, in the wall structure: interior plaster, calcium silicate, solid bricks, mineral wool, air layer, facade panel (wall with ventilated facade). If the wall remains moist, which must be particularly considered in new construction, then water behind a waterproof or water-repellent outer layer, as can be the case with the thermal skin for example, can hardly escape by diffusion and the masonry is damaged over a long period.[1]

[Source 1] Kur, Friedrich; Wohngifte, Handbuch für gesundes Bauen und Einrichtungen

The places where room humidity could escape before renovation are mostly to be found at windows and doors.

Thanks to the planners at the green table in Brussels, a relic from the good old days; meanwhile, at least small ventilation flaps for the windows are again offered – better than nothing.

Furthermore, I do not consider it bad that an unoccupied apartment (both spouses working) is not ventilated during the day, since the moisture primarily arises from the occupants and they are not in the house. As long as the place is not full of plants and aquariums, I see no mold risk.

It’s not that simple; in the evenings and at night, the residents are usually at home and not all moisture is removed by ventilating twice a day – including the moisture from the morning bathroom visit.

In new buildings, moisture inevitably occurs, even though many bricks nowadays are glued – not as much as before, but with the screed, still enough water enters the house and an ETICS simply does not make things easier. You can’t argue against that.

Kind regards