20% humidity in KFW 40+ new construction

We had drying units here in the summer (August) to speed up the tricking of the screed for tiling. Quite a bit of water accumulated? Could it be because we are already so dry now?

- That an EWT only accounts for 5% is something I doubt. Probably (especially with your extreme values) you’re more easily at 10% or more. Our EWT works really well. Another advantage: With EWT, the controlled residential ventilation also runs down to about -7°C outdoor temperature.

Do you mean 5% relative or absolute humidity in the house or how much moisture the EWT returns? An EWT manages to return about 70% of the moisture in the air. P.S. Your controlled residential ventilation stops working at -7 degrees? Why is that if so? P.S.S. Why do you think a controlled residential ventilation always needs an EWT? There are also other very good solutions that work just as well.

Does everyone who has controlled residential ventilation here really have an EWT?

No, you don't have to, but it is easier to retrofit than, for example, a mixed air control.

We don’t have one yet and are at about 32%. But we also have rather low levels and a thousand plants.

No, you don't have to, but it is easier to retrofit than, for example, a mixed air control.

What is a mixed air control supposed to be in a central controlled residential ventilation system and above all, what is it supposed to achieve?

What is a mixed air control in a central controlled residential ventilation system supposed to be and above all bring?

In principle, a bypass of outside air and exhaust air before it goes into the controlled residential ventilation system. This can be used to regulate the indoor humidity and/or to additionally preheat the outside air with the remaining heat in the exhaust air that is not used by the heat recovery. Especially at cold outside temperatures, even e.g. 10 degrees in the exhaust air still make a difference.

We don't have one yet and are at about 32%. But we also have rather low levels and a thousand plants.

Enthalpy and all rooms consistently >45% relative humidity. Nominal ventilation. I am very satisfied with the ventilation - first winter after construction constantly too humid, now in the second exactly right.