Controlled residential ventilation yes - heat recovery no - justification in the text!

Thank you. I have taken a look at the page, they plan everything and supply the parts, but they do not install them, right? Have you planned geothermal exchangers for your site?

Experience after approx. 14 months of central controlled residential ventilation: - Dirt in the ducts not visible - Regular filter cleaning (if I have to inhale everything that is stuck in the filters, I get sick) you can do it yourself - new coarse filter: costs a few cents if you buy roll goods and cut the filter yourself - annual power consumption approx. 250 kWh - the air quality is priceless (a large part of the electricity comes from our photovoltaic system - the system ventilates about 300 sqm floor area for us) - Germs in dry air? Where should they grow? I would rather worry about germs in carpets or mattresses...

Conclusion: Always a controlled residential ventilation + heat recovery, although it costs a few euros to purchase, it is a gain in comfort. Running costs are negligible. Germs? No!

and how did contamination occur in the aforementioned show house after 2 years. One more note: I am not talking about visible dirt. That is not a problem. I am talking about invisible and non-filterable germs.

The germs can only grow in the pipes. If the pipes are dry, there can be no germs!!!

and why was the show house still contaminated? not visible, but measurable.

I think it's great Grym that you engage with the subject matter and are brave enough to share your perspective here, that's what a forum thrives on. Unfortunately, I find the answers here today somewhat unsatisfactory and unobjective. I myself am also more in favor of a controlled residential ventilation system with heat recovery, nonetheless, one can always look beyond one's own horizon. What would be the argument against Grym's solution?

Therefore, in my opinion, the best system with which you never have hygienic problems in the house: exhaust air modules in wet rooms combined with window rebate ventilation or external wall air inlets.