ᐅ 20% Relative Humidity in a KfW 40+ New Build

Ypsi aus NI schrieb:

The passive house is designed for maximum heat retention, and with 6-meter (20-foot) floor-to-ceiling windows facing west in the main living area, it becomes like an oven. It heats up very quickly, even in winter.

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

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

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

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

What does it mean to argue too early? I’m just writing how things are right now...

It was written a bit more provocatively than intended. I was mainly thinking that there must be other factors causing you to describe it that way. Mechanical ventilation with heat recovery, not set to bypass or anything like that. But I have to admit I lack experience in this area. I was just surprised at how cool it was inside 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°C (68°F) with lots of sunshine for the last six weeks. Nights were still cooler, but not anymore since last week. It has also been humid here since the thunderstorms last week. We are now experiencing 60–70% humidity at 25°C (77°F).

We haven’t had any rain or thunderstorms here yet, despite numerous weather warnings. The air outside is still uncomfortably humid. When the doors are open and this air moves into the house, the indoor humidity level is fine, but as someone prone to headaches, I find myself needing to take two ibuprofen right away to prevent a migraine. In this case, the air conditioning helps, probably by reducing humidity, but then the indoor humidity quickly drops to a very low level again.

A brief report from an almost passive house (missing the standard by about 0.1) built to KFW 40 Plus specifications, equipped with controlled mechanical ventilation with earth-to-air heat exchanger and summer bypass. We have humidity sensors in the bathrooms, and since moving in in August 2022, the indoor humidity has been around 50%. The temperature is kept steady at about 23–24 degrees Celsius (73–75°F), and our external blinds automatically adjust based on the sun’s position to prevent excessive heat entering the house. On a few days, however, we still felt the need to let in the cooler air in the mornings and evenings.

We do not have air conditioning and maintain a normal number of plants. So far, neither dryness nor heat has been an issue. Therefore, the airtightness standard alone is not the cause.

Oh, and before moving in, we stored our furniture in the basement storage room for about three months and ran a dehumidifier to prevent mold from any residual moisture in the basement.