Expert: For which construction phases is it urgently necessary?

Airtight boxes

How many shot glasses of heating oil equivalent would theoretically be blown away per year if a switch box, which weakens an exterior wall locally by about four and a half centimeters, were not perfectly airtight sealed?

Energy saving is all well and good, but I also believe without a forensic examination of his baptismal certificate that the Pope is Catholic.

Somehow I lack the visual imagination that there could be black holes of significant size in my house to let energy flow into another universe. Seriously.

There is the Blower Door Test for that. The main thing is that the sum of the black holes stays below the target value.

It's less about saving energy and more about drafts. Otherwise, it whistles through like a fish soup.

That's right, a power outlet tornado is unpleasant. Does it even still exist in a house with [Energieeinsparverordnung]? I only know the problem from our Lower Saxony rental apartments. It was completely unknown to me before.

How many shot glasses of heating oil equivalent would theoretically be wasted per year if a switch box, which weakens an exterior wall pointwise by about four and a half centimeters, were not perfectly sealed airtight?

Energy loss is not the issue at all, but the thermal bridge = risk of condensation = risk of mold. Socket outlets, next to compressible tape installation on windows, are the number 1 weak point as far as I know.

We will also soon need an appraiser / expert. Can someone tell me how high the costs were, with at least 7-8 inspections? And ideally also for the contract review?