ᐅ Controlled residential ventilation or demand-controlled ventilation – any experiences?

Can anyone tell me if a ventilation system with regulated air supply and humidity-controlled exhaust fans in the bathrooms can provide sufficient air exchange without manual ventilation?

Does a central mechanical ventilation with heat recovery (MVHR) system achieve a greater air exchange than the system mentioned above?

And is it possible to skip manual ventilation on cold days?

I’ve read in forums that nowadays well-insulated houses should not be built without mechanical ventilation.

Does a regulated air supply system also work effectively when shutters are closed?

1. Anyone can do a lot! Moisture doesn’t only develop in the bathroom. Personally, I’m not a fan of trickle ventilation because it reduces the "good" insulation properties of the windows.

2. If a mechanical ventilation system with heat recovery is properly designed for the house, it works. And without constantly opening and closing vents.

3. If you cannot or do not want to ventilate manually, you should definitely rely on a mechanical ventilation system with heat recovery—for well-known reasons. Even if the investment in such a system can be costly, it is still better than having moisture damage that poses health risks in the building at some point.

4. Ventilation also works when the roller shutters are down because they are not airtight. But when things get critical, this may not be sufficient for proper air exchange. As you can see, this type of ventilation system is rather questionable. To me, this “ventilation system” is comparable to “tilting the window open.” Eventually, cold drafts come in, and I prefer to close it again. That’s my personal opinion.

Can anyone tell me if a ventilation system with controlled air exchange and humidity-controlled exhaust fans in the bathrooms can provide sufficient air exchange without manual ventilation?

Yes and no...

These systems (1-2 exhaust units in the bathroom and possibly the kitchen) usually provide a basic level of ventilation and increase airflow as needed based on humidity sensors.

This should generally be enough to prevent moisture damage. However, to achieve a “fresh air effect,” it is still recommended to occasionally open the windows.

Depending on how the system is designed and sized, it is of course possible to completely avoid manual ventilation... but the question remains whether this is practical.

Air exchange according to the ventilation rate plan? That’s one thing; actual energy efficiency is something completely different!

First and foremost is ventilation! Excess moisture needs to be removed, and fresh air is generally more pleasant than stale air.
In my opinion, every new build should have an appropriate system in place to provide at least a basic level of protection against mold and similar issues, even if there are a few days without window ventilation.
An exhaust system in the bathroom and kitchen combined with an adjustable air supply system can certainly be sufficient for this purpose.

Whether or not to include heat recovery is, for me, not a question of energy efficiency but rather of cost-effectiveness.
A mechanical ventilation system with heat recovery has significantly higher operating, maintenance, and financing costs, which can easily exceed the heating cost savings overall.
What remains is a certain increase in comfort, but this comes with a higher maintenance effort.

Here, everyone really needs to calculate based on their personal situation (heating costs, financing, etc.) whether heat recovery makes financial sense or not.

Hello Shism,

I see it the same way. From a purely cost perspective, it’s rather questionable whether it’s worth it or not.

For a mechanical ventilation system with heat recovery, I would primarily consider the comfort factor. Unfortunately, the disadvantages of a central mechanical ventilation system with heat recovery are quite significant, and I get the impression that these systems are often overly praised.

A decentralized mechanical ventilation system with heat recovery is less suitable for aesthetic and acoustic reasons.

It’s clear that with a ventilation concept using RegelAir and humidity-controlled exhaust fans, manual airing is still necessary.

The question was more whether it’s still "absolutely necessary" to open windows several times a day for ventilation.

But as I understand it, moisture protection would be ensured with a well-planned system.

cuhnie schrieb:
...It is clear that with a ventilation concept using RegelAir and exhaust fans in wet rooms, manual ventilation is still necessary.

This probably means that the question of cost-effectiveness of this option compared to simple window ventilation does not need to be discussed further.
"Half measures" rarely lead to success!

Best regards