: True, just calculating the operating costs is not enough. That's why I also included interest and depreciation. And they can't really be included in your 300 €. It's the same as with a car: everyone looks at fuel consumption, but for an average driver with 15,000 km per year, depreciation/loss of value is easily twice as high as fuel costs. One liter more or less consumption is (economically) completely irrelevant.
But I agree with you, the controlled residential ventilation can be a great gain in comfort and definitely worth its money. However, we consciously decided against it and it really annoys me that I am now forced by the eco-lobby to hurry with my construction because otherwise next year I will probably have to install one. That just stinks... (don’t get me wrong, it’s not your fault!)
The alternative, according to good old tradition, is manual ventilation. We are both full-time employed and moved into a new building in 2011. The house is already just as airtight as current houses. We had and still have no problems with mold or moisture. However, you really have to take the time to properly ventilate thoroughly in the mornings and evenings (plus even more on weekends) and above all you must not start skimping on heating and let any rooms fall to as low as 15°C. That’s why even our basement is heated throughout the entire heating period.
However, it is a clay brick house (Poroton), which naturally holds much less moisture than, for example, a sand-lime brick house. And the landlord was wise enough to heat like crazy for some time after completion but before our move-in, while also running large construction dryers on the side. According to him, that cost him about 300 € in energy costs, but we moved into a largely dry house. Under other conditions and if you are regularly away for weeks, this may not work.
Best regards,
Andreas