Ventilation systems

my parents already practiced this, you can't do anything wrong and it costs nothing. Although the air is not preheated, ventilation systems with heat recovery do not necessarily operate energy-efficiently either; the operating costs compensate for the heat loss that must be compensated for with window ventilation.

In old buildings, compared to today, there was rather a "airy" condition. In the end, it didn't matter how the energy was "wasted." In highly insulated houses, with supply temperatures of 28-30°C, you ultimately have a cold house with this ventilation technique. Note also the requirements of the SIA standards regarding comfort in living spaces. In addition, there are also decentralized ventilation systems whose energy costs, with a normal EFF, are around 100 to 150 francs per year; their ceramic heat exchanger can even be cleaned weekly via the dishwasher ...well boiling... if there really was a need. So far, nothing has been presented here that speaks against a controlled ventilation system except unfounded prejudices. One should simply inform oneself...

That now sounds like it's from a brochure of the ventilation systems industry. There are also other voices, including from experts, not just unfounded prejudices. What is true, however, is that ventilation must be carried out in a planned manner. Our house is not an airy house, it is already tight, but we ventilate through the windows, cross-ventilation. That works quite well if you do it disciplinedly. So no tilted windows, no forgetting to close a window, etc. Whether we waste huge amounts of energy this way, I can't say; that would have to be compared with a similar mechanically ventilated house.