Which flooring to choose for the ground floor - experiences?

It must be clear: The warmer a floor feels underfoot in an unheated state, the worse it conducts heat (that is why it feels warm) and is consequently less suitable for underfloor heating.

I know cork from my parents, who don't have underfloor heating, and it is pleasant in the bedroom. And yes, it is more sensitive than wood. I had extreme wear under my desk chair in the youth room.

Cork is one of the few coverings where even the manufacturers say that it is not suitable for underfloor heating. There may be exceptions. Your heating engineer is not wrong.

In practice, the effect then depends on thickness, manufacturer, and insulation value. It will work somehow, but it would have been better, for example, to also equip the wall or ceiling with underfloor heating.

What will happen: the flow temperature of the heating system must be higher than usual so that the cork rooms become warm. All other rooms must be throttled because otherwise they become too warm. This costs pump electricity and heating efficiency, especially if a heat pump is installed, which would be unfavorable. Living rooms (sun, usage) and bedrooms often have a slightly lower heating requirement, which could balance it out a bit. With a gas heating system, you could take the risk if you are attached to it; with a heat pump, I would definitely avoid cork.

Vinyl is warm underfoot and, when glued down, performs almost as well as tiles for underfloor heating. Even with floating installation of very well-conducting coverings (no wood components), I see higher return temperatures.

The ongoing additional heating costs are hard to quantify. Probably not more than 25% worst case.

It is loud, hard and extremely cold underfoot.

But not more than wood? Neither in terms of hardness nor coldness underfoot. Maybe a short-pile, low-maintenance carpet would be optimal in the bedroom after all?

Vinyl is warm underfoot

I don't find that at all. In our current apartment, we have laminate in the living room and vinyl in the hallway, and we find the hallway colder.

But surely not more than wood? Neither in terms of hardness nor coldness underfoot. Maybe a short-haired, low-maintenance carpet would be optimal in the bedroom after all?

Topic is settled. See the house pictures thread. We debated back and forth until three weeks ago. The construction coordinator said mix (saves the budget and feels better in the "living room"), the parquet installer said don't mix tiles and laminate (it looks dumb with rails). Since our budget will easily cover it, we decided on the tiles. We will now mix 20x120cm and 30x120cm tiles on the floor everywhere (wild pattern). In the bedrooms, high-quality abrasion-resistant laminate from a specialist dealer will be installed by the parquet installer. We have it installed because the price is extremely good and because my construction coordinator had to help too much on another site with private installation to properly install the vinyl.

With us, the vinyl is significantly warmer than the tiles. Laminate is "considered" cold, but I don't have any left and therefore no direct comparison. It probably depends, as always.