Building a single-family house in NRW

Blind control please without technical devilry, but when replacing analog window ventilation it is helpful. I don't have to understand everything.

Controlled residential ventilation saves 30-50 minutes per day. A perfectly adjusted window automation, which always does exactly what I want and where there are no switches, no remote control, and no app, saves a maximum of 1 minute. An imperfect automation costs time. That doesn’t mean it can’t be done. Steffen spends 80,000 EUR on his automation. That’s possible if you want to. In our opinion, that’s where the limit of "reasonable" is exceeded. That’s our opinion, mind you. Someone else might see it differently.

I clean my windows definitely more often than every ten years, and a fly screen in midsummer is air filter enough for me.

Nice for you. But fly screens and F7 filters have nothing to do with each other.

I do appreciate that in a controlled residential ventilation house the air is noticeably cleaner than outside in the ambient air. The fine dust/diesel/direct injection issue will accompany us for at least another two decades, and it is already proven today that fine dust damages lungs and heart. It’s like smoking yourself. If you are shielded from that at least half of the day you spend in your own house – that’s a good thing.

Filters should also be changed much more often than every 10 years. Several times a year, possibly quarterly. That’s where all the crap collects that has not entered the house but was filtered out. And quite a lot collects there. You have to consider that otherwise it would be inhaled.

And the burdens from VOCs, formaldehyde, etc. are invisible but present. Just because you don’t see it doesn’t mean it’s not harmful. Didn’t a user just compare this to radioactivity?

To avoid fully entering this fundamental discussion (which has already been conducted multiple times in this forum) and to perhaps provide the thread starter with some orientation help: I had the same discussions, but they did not advance my question because I do not know which "camp" is actually right. For that, I have spent countless hours on Google.

What I am now saying comes from the knowledge I gained through this very research, based on statements from other people, what my head retained, and perhaps what my gut feeling tells me. All those who post in favor of controlled residential ventilation have one themselves and have verified their experience after years ("never again without" is not a rare phrase). Those who shoot against it almost always do not have controlled residential ventilation.

I have read about this several times, and my heating engineer also explained it to me independently, and physically it seems logical to me: For mold and germ formation, moisture on/in the pipes is needed. For moisture from the air to adhere to the pipe (condensate), the so-called dew point must be undershot. This can happen, for example, when the moist room air at 21°C flows through pipes that are located in an unheated/insulated area of the house (e.g., attic). This could cause the dew point (roughly 8-15°C, I believe) to be undershot, and condensate forms. If this is not the case, nothing can happen. Because like clothing in the wind (= inside surfaces of pipes in the airflow), it is rather dried than made wetter (the pipes are even dried).

Guides of all kinds, at least the KfW, all craftsmen with whom I have had conversations, and home builders anyway (they want to sell) say that with modern houses with tight building envelopes, the moisture must go out. How exactly (manual ventilation, controlled residential ventilation, passive window ventilation) does not matter as long as it works.

It is also true that moisture only occurs where it is produced. That is primarily the person themselves. Then there is cooking, wet laundry, and showering. Unused rooms, which also remain unheated, may again have a dew point problem. Where you are anyway, you can also ventilate. But hand on heart, do you do it? If yes, that is good.

That not even one of the experienced owners after several years has had a germ test done and shared the result surprises me somewhat, as from the experience of several owners it would be a strong argument and even in one’s own interest. But correct me if I am wrong, I have found nothing except minor statements.

Provided the filter is changed quarterly (also use exhaust air filters!)

what do you mean by exhaust air filters? We get filters both at the supply air and in the Zehnder ComfoAir Q.

Steffen spends 80,000 EUR on his automation. You can do that if you want. In our opinion, this exceeds the limit of what is "reasonable." At least in our opinion. Someone else might see it differently.

But that is not really an argument. For some, a car with 130 HP is no longer reasonable... for others only at 300 HP... So basically, that says nothing at all. If I were to list here... everything our house takes care of and at which points it sometimes "thinks along" (keyword security, burglary, fire, etc.), we could certainly argue about sense/nonsense for a long time.

By the way, the 80,000 EUR does not only include the automation but the entire electrical system. For our house size, that would normally be around ~20,000.

Regards, Steffen

Filters can be installed directly in the exhaust vents. Whatever dirt remains in the kitchen after the recirculation filter then does not enter the pipes but stays in this filter directly in the exhaust vent. Of course, dirty exhaust pipes are basically not a problem either, since the airflow always runs in one direction when the system is running. But you can also equip the exhaust vents with filters and keep the pipes clean as well. It is important that the system runs 24/7. Exhaust systems that have no filter or a broken filter and only run as needed and otherwise stand idle for 23 hours are indeed hygienically problematic – but have nothing to do with a controlled residential ventilation system. Similarly, one could take a moped rider in a large African city and, based on these findings, conclude that driving a new Mercedes GLS on a German autobahn would be dangerous.

Filters can be installed directly in the exhaust vents. Whatever dirt remains in the kitchen after the recirculation filter then does not go into the pipes but stays in this filter directly in the exhaust vent.

That's the theory and maybe for some also the practice, but personally I am not convinced. The activated carbon filters in recirculation mode already block the airflow and the system is automatically louder. They probably do not filter all odors and grease, and according to recirculation hood manufacturers, the hood must be regularly wiped from the inside (who actually does that? I suspect very few). The carbon filter must also be replaced regularly (once a year?), but that should still be manageable.

An additional filter in the exhaust opening seems reasonable. But I do not believe that nothing passes through there either; probably it is just very little.

Exhaust hoods are a total disaster from an energy perspective. Nevertheless, I am getting one at my own request. There are plenty of customer opinions on this topic online, and here there are just as many supporters as opponents.

Filters can be installed directly in the exhaust vents. Whatever dirt remains in the kitchen after the recirculation filter then does not go into the pipes but stays in this filter directly in the exhaust vent.

Of course, dirty exhaust pipes are basically not a problem because the airflow always runs in one direction when the system is running. But you can also equip the exhaust vents with filters and keep the pipes clean as well.

It is important that the system runs 24/7. Exhaust systems without a filter or with a broken filter that only run as needed and stand still for 23 hours are actually hygienically problematic – but have nothing to do with a controlled residential ventilation system. Likewise, one could take a moped rider in an African big city and conclude from these observations that driving a new Mercedes GLS on a German autobahn would be dangerous.

Absolutely agree with you.

Filters can be installed directly in the exhaust vents. Whatever dirt remains in the kitchen after the recirculation filter then does not go into the pipes, but stays in this filter directly in the exhaust vent.

I think I confused supply air with exhaust air. We get filters where the used air is "sucked out." Where fresh air comes into the room... there are no filters. That's correct, right?