20% humidity in KFW 40+ new construction

The passive house is designed for maximum heat retention and with 6m floor-to-ceiling windows facing west in the open plan living area, it’s like an oven. It heats up very quickly, even in winter.

So I understand that if it’s been really hot for weeks. But isn’t it still a bit too early in the year to argue that the house has heated up so much that the heat can’t escape anymore?

The garden and the terrace are just being created. Even though we wish for a lush garden, the plants will probably never shade the house.

Using ground cooling is out of the question for us. My husband still finds cold tiles uncomfortable even in summer.

The interaction between the climate and the EWT will have to prove itself.

What does it mean to argue too early. I'm just writing how it is right now...

Was written somewhat more provocatively than intended. It was more about the fact that there must be other factors that lead you to describe it that way. Controlled residential ventilation not on bypass or anything. But I have to admit that I lack experience there too. I was just surprised how cool it was in our house (not yet moved in) after the warm days.

It also depends on how long it has been warm. For some, it has only been hot for one or two weeks. We have had only days over 20° with a lot of sun in the last 6 weeks. Nights still cooled down, but not anymore since a week ago. Here, it has also been humid since the thunderstorms last week. We then also had 60-70% at 25°.

We have no rain or thunderstorms here, not yet. Despite numerous weather warnings. Outside, the air is still unpleasantly humid. When the doors are open and this air pulls into the house, the humidity inside is fine, but as a person sensitive to headaches, I can immediately take two ibuprofens before it ends in a migraine. In contrast, the air conditioning helps again, certainly also through dehumidification, but then we quickly reach a very low humidity level again.

Small report from an almost passive house (missed the standard by 0.1) with KFW 40 Plus, controlled residential ventilation with EWT and summer bypass on. We have humidity sensors in the bathrooms and since moving in in August 2022 about 50% humidity. We keep the temperature constant at about 23-24 degrees, but our blinds also adjust automatically according to the position of the sun so that heat doesn’t enter the house too much. On a few days, we still felt the need to let in cooler air in the mornings and evenings.

We don’t have air conditioning and a normal number of plants; so far, neither dryness nor heat has been a problem. So it’s definitely not due to the airtightness standard.

Oh, and before moving in we stored our furniture in the basement storage room and ran a dehumidifier there for about 3 months so that nothing would mold from residual moisture in the basement.