Aluminum windows or plastic windows with aluminum cladding

One must say that plastic windows have caught up. Due to the heaviness of today's windows, the plastic frames are made more robust and are often fiber-reinforced. They also insulate better than aluminum. In our current rental apartment, there are 21-year-old white standard plastic windows installed. They still look almost like new... at least cleaned.

No

Really not? Aluminum is one of the best heat-conducting materials around. How do you manage good thermal insulation with it? Plastic is already a very good insulator on its own.

What value do good aluminum windows reach? Our plastic windows have a Uw = 0.69.

Really? Aluminum is one of the best heat-conducting materials there is. How do you manage good thermal insulation with it? Plastic is already a very good insulator by itself.

Oh, are you also someone who hasn't "caught on" yet? Yes, the problem with aluminum profiles is known, but it belongs to the past: that was true for the first generation of aluminum windows, but for about forty years now, aluminum profiles have been built in two halves with a plastic strip in between.

Oh, are you also one of those who "haven't" noticed it yet?

To be honest, I've never been interested in windows at all. I also don't know anyone who has aluminum windows. They are always plastic or wooden windows.
Our window manufacturer also only has aluminum windows, which insulate worse than their best plastic windows. From a materials science perspective, that made absolute sense to me. I did not delve into construction details afterwards. My bad.