Usable basement: Insulate, heat, raise ceiling?

Just read the data: outside 1.1°C, supply air 16.1°C, basement 18.4°C. Yes, some heat is lost, but at least regarding humidity, there is no problem. On the contrary, I extract moisture – and at the same time use the waste heat from the technical room in the basement.

Just so we don’t talk past each other: it is clear that the controlled residential ventilation unit can be placed in the basement, as well as the piping for outside and exhaust air. But an uninsulated and unheated basement outside the thermal envelope and yet the house’s controlled residential ventilation supply/exhaust air also in that basement? Well, I wouldn’t dare...

Our controlled residential ventilation system is located in the attic. All basement rooms are connected to supply or exhaust air. The basement corridor is part of the thermal envelope due to the open staircase. Otherwise, there is only perimeter insulation on the outside, I think 10cm, and Styrofoam under the screed, no insulation under the floor slab. In the largest room, we even had underfloor heating installed, which is occasionally activated as needed.

What are you afraid of? I do not want to rule out that heat losses could cause problems with target values like KFW-40 or similar, we built according to the normal energy saving regulations.

Oh dear, I just had my own experiences with Gussek Haus in building services and terminated our construction contract after half a year, I hope you have better luck.

Oh wow, do you want to elaborate on that? I need to take a closer look at the topic again.

I can gladly do that, but not publicly in the forum. If you have specific questions, just contact me.

An example:
We wanted a KNX installation. The planning was all done, the room concept was available, it was basically just about routing the right cables to the right places. After weeks of discussions, there was a telephone conference between the electrician, the "seller," and the planning department that lasted a full 4 hours – mind you, without me. Result: I was told literally: "We actually don’t know exactly what you want, but we can already say, that will cost at least 50,000 € extra just for the wiring plus the technology. And we would have to do planning with the electrician here with you for that, for which we estimate 5 days, which we have to charge at 1,000 € each."
Translated: We can’t do it, but the company philosophy is we make everything possible. We just have to make sure the customer no longer wants it willingly.

We were only able to get out of the construction contract because we had a self-formulated cancellation clause added to the contract. Shortly after confirming the cancellation, our local salesperson was no longer working for Gussek Haus...

Our controlled residential ventilation system is located in the attic. All basement rooms are connected to supply or exhaust air. The basement hallway is part of the thermal envelope, because of the open staircase. [...], we built according to the normal Energy Saving Ordinance.

Regarding the Energy Saving Ordinance, it is also a private matter whether to connect a cold basement to the common controlled residential ventilation system – in the upscale KfW efficiency classes, I see two separate controlled residential ventilation circuits being necessary (with or without heat recovery).

There is only perimeter insulation on the outside, I believe 10cm, and the Styrofoam under the screed, no insulation under the base slab. In the largest room, we even had underfloor heating installed, which is activated as needed.

Just read the data: outside 1.1°C, supply air 16.1°C, basement 18.4°C. Yes, some heat is lost, but at least with regard to moisture there is no problem. On the contrary, I extract moisture – and at the same time use the waste heat from the technical room in the basement.

Your statement and 18.4° basement temperature are really not uninsulated and unheated. No idea how will ultimately decide, but if it is a pure utility basement without perimeter insulation, without base slab/screed insulation and without heating, I would for example have concerns about condensation moisture on cold basement walls in summer. Leaving aside influences and possibly requirements regarding KfW.

From my point of view, this only means separating the controlled residential ventilation of the basement and the living area, i.e. installing two central controlled residential ventilation units in the house.

Yes, that can certainly be done. But in my opinion, it’s like using a sledgehammer to crack a nut. For ventilation with moisture protection, the mentioned Maico AKE units are certainly the more pragmatic option.