ᐅ Unusually high quote for ventilation system

Youtube > Ventilation System – Is It Necessary? An Energy Consultant Explains

In 2015, I had a multi-family house with 6 apartments built to KfW55 standard. This building has been rented out since early 2016, so for almost 8 years now. Over the years since the rental started, there have been many tenant changes; in every apartment, there is now at least a second tenant. After many discussions with experts back then, I ultimately decided against installing a ventilation system due to cost reasons. The cost of a ventilation system would have had to be factored into the price per square meter. In other words, renting out at a slightly lower price per square meter has been more economical for me. My primary concern was the issue of mold growth. In the 8 years since renting, I have never had mold problems in any of the apartments. I agree that a ventilation system significantly increases comfort, but my example shows that it is also possible without one. I don’t believe I have simply been lucky to rent only to the best tenants in all of Germany.

I am not saying that maintenance is necessary; the manufacturers state that.
Manufacturers also void the warranty and guarantee if you perform the maintenance yourself.
Of course, you can save money by doing the work yourself.
But that is not the typical case.

From my perspective, one of the main reasons why ventilation systems in residential construction are so absurdly outdated is the landlord-tenant relationship: The landlord understandably only focuses on construction costs. So far, the tenant has paid little attention to utility costs. Heating costs go up a bit? Only the tenant notices. Damp corners or moldy silicone seals? Only the tenant notices and doesn’t dare say anything because if they do, they understandably get scolded by the landlord to "just ventilate properly." This is ignored to death and at best treated with one of the many widely sold mold removers for good reason. Condensation is streaming down the windows? No problem; a friend of mine is currently installing triple-glazed windows throughout the entire house to fix that.

So yes, as a landlord, you only really have a mold problem when it’s far too late. Not because there was no mold before, but simply because it wasn’t visible. That’s the perspective from a few decades of being a landlord.

The fact is: The only argument against controlled residential ventilation is the initial investment. And when I see some “I took the model house and made everything 20% bigger” and “I can’t live without a double garage, a lemon squeezer roof, and a fully glazed south-facing wall” house designs, and then hear “well, a kitchen with a granite island and steam oven just costs 30,000” while an SUV with extras of the same value parks in the driveway, I do wonder about the double standards here. In Cologne, they say “kitchen laminate, living room brocade,” and all the infrastructure is built as cheaply as possible. Heating? Water? Electricity? As cheap as possible. As if we didn’t already have enough unsalvageable buildings made from paper-thin panel construction, we happily continue to build structures in the landscape where the core has been skimped on.

OWLer schrieb:

I would have said just have the ductwork installed and then connect the unit yourself. Is that what you mean?

Simply install the ducts up to the manifold and then buy, connect, and commission the unit yourself. Such a device is as complex as a toaster.

Or do everything yourself. From the air distributor onward, we installed the ductwork and connected the valves ourselves. The rest was done by the plumber. But you’re right, controlled residential ventilation is easy. Next time I’m building a house, I’ll do everything myself 😉. Like with the wall heating—I had it done, next time I’ll do it myself (P.S. There probably won’t be a next time, I’m 56 and actually planned to stay there until I migrate).

Yes, looking back, I also find the system surprisingly simple. The ventilation system is what I have modified the most. A duct is just a duct, and no water can leak from them. In the utility room, I optimized the supply air to better support the photovoltaic system and server cabinet, which I confirmed through measurements. I also found the installation of the ducts very straightforward.

The system design is not an area to cut corners. Some acquaintances used the manufacturer’s sizing tool, but based on experience, it was too small and now runs continuously at full capacity. It’s also important not to skimp on the silencers.