[netnichols]

My German apartment has drafty, unsealed wooden window frames, and the window in the kitchen is a single large sheet of glass. We have to hang a rug over that window in the winter, as it feels like you've left a freezer door open if you get within 3 feet of it.

But the walls are indeed very thick!

[stinos]

I don't speak German so I cannot look it up, but my guess is these standards are for new buildings or buildings that are being renovated (and probably the numbers are different for private and commercial buildings as well, which is a shame), and owners of an existing building cannot be forced to adhere to the standard. Thickness of walls is of course related to insulation, but it isn't everything; for example 20cm of typical insulation still has a much lower U-value then a concrete wall of 100cm thick.