Thermal curtains - do they work - who has experience?

My house (ecological timber frame construction) is built quite openly, I have as few doors as possible. The basement is designed as a living area and can be heated. The problem with this open construction is (no surprise): when it is pleasantly temperate in the basement, it is terribly warm upstairs (well, heat rises upwards). Since I do not want to “install” doors retroactively in my house, I thought of a thermal curtain. So a thermal curtain at the basement stairway so that the heat does not rise into the ground floor – and a thermal curtain at the ground floor stairway so that the heat does not rise to the upper floor. Does anyone have experience with thermal curtains? Which ones would you recommend?

Summer or winter?

I can't imagine that this will do any good. Only with rapid/short-term temperature changes should this be able to delay a temperature/air exchange. The curtain will still warm up quickly, take on the surrounding temperature, and also transfer it.

In modern houses, it is almost impossible to achieve significantly different temperatures in individual rooms or areas than in the rest.

In modern houses, it is almost impossible to achieve significantly different temperatures in einzelnen Räumen oder Bereichen than in the rest.

But

That's exactly the problem. In the basementBereich it is 19 degrees and in the upper floorBereich 25 degrees.

But that is not because heat rises, as you suspect.

I can't imagine that this would bring any benefit. Only with rapid/short-term temperature changes should it be able to delay a temperature/air exchange. The curtain will still warm up quickly, take on the ambient temperature, and also pass it on.

In modern houses, it is almost impossible to achieve significantly different temperatures in individual rooms or areas than in the rest.

Well, I have 23 degrees in the living room, 26 degrees in the bathrooms, 17-18 degrees in the bedrooms...

I do think that such curtains can cause a certain improvement. It's not about the heat transfer of the fabric, but about reducing any possible "thermals" (convection currents).