ᐅ Unusually high quote for ventilation system

@HeimatBauer
Where did I ever claim that ventilation does not cause energy loss?
I even tried to estimate the amount for our household in my posts.
Your comments, on the other hand, have slipped to a low-brow level.

@WilderSueden
I don’t see what’s so questionable about it. The 20,000 euros have to come from somewhere. Either you have that money available, save it somewhere else, or you have to finance it. If you then compare your repayment plan before and after financing, you will find that the total difference at the bottom line is exactly over 40,000 euros. Of course, inflation works in your favor here. For the investment calculation, you would also discount the entire amount.

Musketier schrieb:

I don’t see what’s so unreliable about it. The 20,000 euros have to come from somewhere.

Somewhere the money for beer at the pub, the car, the vacation, and so on has to come from as well. Either you spend it or you invest it. It’s exactly the same logic. No one (except financial influencers with clickbait titles like “your coffee costs you $100,000”) would think of calculating it that way. You would also have to include your own working hours, of course with interest and nighttime or holiday pay 😉

It obviously fits well with your argument that adding interest makes the controlled ventilation system seem more expensive, making it easier to argue that it’s not worth it. But that distracts from the real problem, which is that in modern, airtight houses, the necessary air exchange rates can’t be achieved with window ventilation. This becomes clear in every single case by looking at the ventilation plan. Especially not by airing once and letting the cat in or out three times. The claim that this would provide sufficient air exchange has no physical basis at all.

This is a classic cost comparison calculation used to evaluate an investment. However, if you believe that you can completely disregard business administration principles, then there is no point in continuing this discussion. By doing so, you disqualify yourself.

WilderSueden schrieb:

The claim that this would provide sufficient air exchange lacks any physical basis.

Exactly. In my experience, window vents only create the illusion of air exchange because you can feel a draft. But when you actually measure it, the air quality is terrible, and humidity remains a serious problem away from the front door. That’s why myths like the “dark basement” persist. My basement has full living space quality, thanks in part to proper ventilation.

It’s obvious that the simplistic argument “the house is free but the ventilation costs millions” doesn’t make sense. But people have to cling to something to justify it. Nothing pays off as well as a controlled residential ventilation system, so it makes sense to save on many things—but not on that.

I am generally in favor of mechanical ventilation with heat recovery, but I don’t believe it’s economically justifiable for an owner-occupied single-family house. However, it doesn’t have to be. No one tries to justify the extra cost of a lift-and-slide door system with a business case. Or large windows in general. Smaller windows are much more efficient. Laminate flooring offers the best value for money, yet people often choose something else if they can afford it, even without reducing ongoing costs. A single-family house itself is usually not a good economic investment in most cases. Mechanical ventilation with heat recovery doesn’t deserve to be justified solely as an energy-saving miracle. It simply provides greater comfort. Even more so for allergy sufferers. Whether the increased comfort and well-being are worth it is a personal decision. But one thing I’ve noticed is this: there are hardly any reports from critics who have actually lived with one. Mostly, the experiences come from people who wouldn’t want to do without it afterward.

In an owner-occupied single-family home, many things are done differently than in industrial or office buildings—especially since users often unintentionally undermine the entire system: The heat pump is set to 70°C (158°F) all year round “so the hot water is really hot and the mixing valve lever stays in the middle at a comfortable temperature,” and of course the classic “turn the heating to 5 so it warms up faster.” When it comes to ventilation, windows are left open all year round, ensuring the ventilation system definitely won’t work. However, I cannot blame the technology or advise against it just because people are unwilling to operate it properly.

Yes, a mechanical ventilation with heat recovery pays off differently than a pure investment like rooftop photovoltaic panels, which I calculate precisely in Excel and install once the numbers add up—and then usually forget about. Mechanical ventilation obviously pays off more slowly through heating cost savings, but it does pay off. Unfortunately, this word has been horrifically misused a lot in recent months. The technology itself is open-ended: just as I can heat my underfloor heating with a system that may not yet exist, I can eventually upgrade my ventilation with a better (control) system. And this is not a “maybe someday,” like e-fuels; such technology is already being installed today, for example, in schools where individual rooms are truly ventilated based on demand. I’m starting to consider that for my own home as well.

The main aspect, as I mentioned at the beginning, is the massive improvement in quality of life. When I see what some people install—gold-plated faucets in their homes—but then cut corners on infrastructure—well, everyone is the architect of their own fortune. Yes, in my sauna and wellness area, I treated myself to very comfortable tiles because I walk barefoot there a lot, but in the rest of the basement, I used simpler tiles that I have come to like surprisingly well, and overall I even ended up with a slight gain on the tiling budget. Summer, winter, draft-free, mold prevention, noise, insect, and burglary protection—simply perfect air 24/7. That’s why absolutely all of my acquaintances with a central mechanical ventilation system have clearly said: never again without it.