Atypically high offer for ventilation system

We'll see each other again in 5 years in the thread "Help, mold everywhere in the house and guests say they get headaches from us." Ventilating once a day contradicts all recognized rules for ventilation concepts in new buildings.

I seriously wonder how houses from the 2000s can still stand. We have been living in the house for almost 10 years and have no mold. The upper floor is ventilated once a day and partially the bathroom and bedroom again as needed. The ground floor ventilates more or less by itself when we go out and come back in, let our cat out and in, etc., or when we cook, then again as needed. Currently, we have values around 40% humidity, so rather too low. If it’s more humid outside, then sometimes a bit more. Surely, it doesn’t compare in comfort to a ventilation system and you can’t just close the "ventilation windows" either, but I don’t need more than 1 minute to open and close windows.

Here 5 years in a new building with a central ventilation system with a heat exchanger, before that 10 years in a new building with a decentralized system, and before that always houses without ventilation systems.

For me, the ventilation system with a heat exchanger is the aspect that increases the living quality the most, reduces the conflict potential regarding ventilation to zero, and at the same time actually saves a significant amount of energy. Decentralized systems are purely token measures in practice that are immediately deactivated, meaning we ventilate like in the Stone Age.

For the next house construction, I would do very little differently than in the current house, adapt some things to the hopefully available technical innovations at that time, but what I would never, ever do without is a central ventilation system with heat recovery. We have made compromises in comfort/luxury at many points in the house (for example, we received a five-figure amount credited for the bathrooms), but fortunately, saving on the ventilation system never crossed our minds.

If the contract with this general contractor is not yet signed, I would seriously reconsider at this point. Anyone who is so deeply and firmly stuck in the past that they categorically advise against ventilation systems is giving themselves a very clear testimony. And not a good one.

but I don’t need more than 1 minute to open and close windows.

Let's say you have 5 windows per floor and two floors. Then you have 6 seconds to walk to the window, open it, and secure it against slamming on the lee side. Doors also have to be secured. There's no way you can manage that in a minute. We could even subtract one or two windows, you only get close to a minute if you sprint through the house.

I seriously wonder how houses from the 2000s can still stand. We have been living in the house for almost 10 years and have no mold. The upper floor is ventilated once a day and partially the bathroom and bedroom again if needed. The ground floor ventilates more or less by itself when we go out and come in, let our cat out and in, etc., or for example when we cook, then again if needed. Currently, we have values around 40% humidity, so rather too low. When it is more humid outside, then sometimes a bit more.

Well, what is the energy demand of the house from the 2000s? The tighter the houses, the bigger the problem that moisture cannot get out. Maybe less in winter, but even then you have to shower/bathe and wash clothes and probably dry them inside. Depending on lifestyle, a lot of moisture can accumulate. For example, we don't put everything in the dryer and I am very grateful that I can hang laundry inside in winter without having to worry about the moisture.

Let's say you have 5 windows per floor and two stories. Then you have 6 seconds to run to the window, open it, and secure it against slamming on the leeward side. Doors also have to be secured. No way you'll manage that in one minute. We can also subtract one or two windows here, you only get close to a minute if you sprint through the house.

As I said, we primarily ventilate the upper floor early with 5 windows in a targeted way. Securing is only done if there is really strong wind, and yes, I can do that in 30 seconds. Usually, ventilation happens incidentally. For example, you make the beds and at the same time open or close the window. On the ground floor, the patio door is sometimes opened intentionally; otherwise, the rest happens while going outside. You quickly go to the trash/compost, let the cat out or in, or our uncontrolled living room ventilation called child chats a little longer at the open door with the neighbor's kid, etc. The house is from 2014. Electricity consumption for heating is 2300 kWh including hot water, pumps, and valves (if still in operation) for 125 m².

In my enthusiasm for the quality of life I experience every day since the new construction, I initially tried to make this gain in quality of life accessible to other people who are currently in the building decision phase. The core of the counterarguments was usually a hurt "I have ventilated like this for 40 years, if I have done it this way for 40 years then it can't have been wrong, so I will continue to ventilate through the window because otherwise I would have to admit something to myself" – and against that I cannot and do not want to argue. That is why we will probably still see Stone Age window ventilation in houses built in 2023 and probably even in 2085. That is why, even in currently built houses, we will continue to waste energy senselessly with every ventilation against all knowledge and rationalize it with a defiant "Gas is still cheap!!!111oneeleven."

For me, central ventilation with a heat exchanger is one of the few immovably set features that every new house should have. And if in 10, 20 years some new ventilation or heat exchanger technology should come on the market: No problem, then the current ventilation unit comes out and a new one goes in, and I am happy that I laid the ventilation ducts. Maybe in a few years there will even be a connection to my home automation, who knows.