From when is a heat pump worthwhile in an old building?

Of course, I would also renew the windows here, these are insulated glass windows, so there is even more to do.

So, the heating needs to be replaced anyway.

For the design and calculation, I can recommend a good engineering office. Just google Ing. Heckmann. Underfloor heating then probably with 7.5 or possibly 5 cm installation spacing. Can work really well. New windows and insulating the basement are really good measures.

thought there might be some general statements like, for example, a house needs insulation X or not.

No.

For the design and calculation, I can recommend a good engineering firm. Just google Ing. Heckmann. Underfloor heating then probably with 7.5 or possibly 5 cm installation spacing. Can work great.

New windows and insulating the basement are really good measures.

No.

OK, thanks. I will contact them. Can someone estimate roughly how much something like that would cost for 140 sqm of living space? Mostly there is already screed everywhere, about 50 sqm still covered with tiles. Living room and bedroom have floating screed.

Or is it not possible to estimate at all what that would cost?

The search for a gas provider should already provide the answer. ;-)

In general, any house can be operated with a heat pump. It just varies in effort. Underfloor heating is already a great prerequisite. An insulated roof as well. Then make sure that there are no drafts anywhere and insulate the basement from below by yourself. Then, with the help of various forums, properly size the heat pump, omit the buffer, and you'll heat cheaply and environmentally friendly.

In fact, it would be helpful if you could get some data from the previous owner such as oil consumption and room temperatures. Then you can make initial rough estimates of how well or poorly the house is insulated.

Built in 1960, roof will be newly insulated and covered, basement ceiling insulated by ourselves, and neither particularly good nor bad windows > that is our starting point. Can you explain to me why no buffer tank (heating engineer offered/recommended one). I would like to understand the background. Thanks in advance

Built in 1960, the roof is being newly insulated and covered, basement ceiling done by ourselves, and neither particularly good/bad windows > that is our starting point. Can you explain to me why no buffer storage tank (the heating engineer offered/recommended one to us). I would like to understand the background. Thanks in advance

And the facade? How is it insulated?

And the facade? How is it insulated?

It is not really insulated, except inside with about 2 cm styrofoam panels. Windows double glazing (renewed about 15 years ago)
Underfloor heating on the ground floor definitely. 1st floor and attic possibly low-temperature radiators or also underfloor heating. Living space 170 sqm

... which is why no buffer tank.

They cost money, have losses, and eat efficiency. Additionally, they are often not installed in series (which is still somewhat tolerable) but in parallel, which brings a second pump and many hydraulic problems. They are only installed because mistakes were made beforehand: hydraulic short circuits, installing individual room controllers, oversized heat pump... If the heat pump is properly sized, the rooms don’t have thermostats (that’s no longer done, another topic), and you don’t get the idea to not heat several rooms at the same time (that’s not done either), you don’t need a buffer tank. That saves thousands right at installation and just as much over the lifetime. And yes – heating engineers are often afraid of that. Educate yourself and demand it.