Building a single-family house in NRW

When you ventilate, the 1.2 kWh are simply gone. Thanks to heat recovery, they are not. This aspect should not be omitted.

What is being omitted there? With you, the 1.2 kWh are also definitely gone. Or does the controlled residential ventilation run with love?

Yes; air and love. No, but the energy is used to warm the fresh air. In other words, the heating has less work to do to bring it back to room temperature.

You really have to look at the overall energy balance.

By the way, the energy loss that occurs when you stick to the values for manual ventilation described in a DIN standard is even higher.

The energy probably goes more towards the fan. There is no preheating, at least not intentionally. The thermal energy that is recovered is a different matter. Someone clever can certainly calculate that (or someone who has [Kontrollierte-Wohnraumlüftung] can look at their heating load calculation), but it is doubtful that it is cost-effective. You can take it even further. [Kontrollierte-Wohnraumlüftung] with [WRG] reduces the heating load, possibly allowing for a smaller heat pump, shallower drilling for geothermal energy, etc., which saves on investment. Still, it (figuratively) won't be economical. The next one saves basement windows through [Kontrollierte-Wohnraumlüftung], etc.

The overall energy balance looks like this:

With controlled residential ventilation: 1.2kWh electricity for ventilation + 16% of 1.2kWh for heat
Without controlled residential ventilation: 1.2kWh for heat

So I don't see the energy advantage in this very simplified consideration.

The calculation is fundamentally wrong. The savings result from the thermal energy that is recovered from the air ventilated out of the room. With an open window, this energy is lost 100%, and reheating is necessary. The controlled residential ventilation returns 84% or, depending on the model, even more of the thermal energy back into the room. However, this has nothing to do with the 1.2 kWh of electricity needed to operate the controlled residential ventilation for one day.

I also don’t understand why people here talk about opponents of controlled residential ventilation... I haven’t seen any in this thread yet... For me personally, it’s just important to EMPHASIZE that controlled residential ventilation is not a must. It has advantages if I have one. For example, I have now had my advance payment from the supplier for the heat pump newly determined, logically based on last year’s consumption. €53/month for 145 sqm. If I now generously calculate 20% savings and disregard ongoing operating costs, where does that get me? Right... Comfort gain, okay. Automatically mold in the house without it... No. Alright, that’s enough now. And some explanations and comparisons made here really seem very much like clip school. Sorry, dealing with that is really too stupid for me.