Construction project - ventilation system, heating - your experiences?

Oh yes, and why do some GUs install rather poor heat pumps and skimp on insulation? Poor insulation means that the heat pump has to work harder (earlier use of the electric heating element, etc.) and then nice consumption figures on paper are no longer possible?

The GU is not interested in your consumption.

Take care yourself: read up, avoid planning errors in hydraulics and underfloor heating (room-by-room heat load/installation plans). Ideally, install the trench collector yourself and buy the heat pump yourself or negotiate something with the heating engineer, because that saves significant money. Alternatively: buy a compact air-to-water heat pump yourself. When building with an architect instead of a GU, this is an option if you have the time to take care of it.

We were recommended the combo with ST by the energy consultant – as I said, I am now curious about our energy consumption when I can get a better overview of it. Currently, we are still in the process of finding the optimal setting for our heating – that will probably take some more time. At the moment, our supply temperature is definitely too high (40°), but it was really cold at the beginning. However, I believe there is still a lot of optimization potential. But for that, we would first have to engage intensively with our home technology as a whole – we haven’t gotten around to that yet. An introduction from the installer of our GU is also still outstanding (still to come) – so I am still relaxed.

With gas it's not so bad... but even there you can certainly optimize by a few % to better utilize the condensing effect.

40° with heat pumps means roughly double the electricity consumption compared to what would be necessary. With the current weather, we are at about 24-27° flow temperature. That only works if the underfloor heating was designed for low temperatures.

Is all the fuss about hydraulic balancing, deactivating the thermostats & co. with a gas boiler even worth it?

But if you switch later from gas to heat pump then it would have been better to plan properly from the start (underfloor heating).

Since you are a fan of gas heating. If gas prices are high in 10 years and you switch to a heat pump now, that reads as a problem. Why?

40° with a heat pump means roughly double the electricity consumption compared to what would be necessary. With the current weather, we are at about 24-27° supply temperature. This is only possible if the underfloor heating was designed for low temperatures.

If I can trust our display, then we are still feeding in even in cloudy weather... But as I said, we have not had an introduction yet and our installer is still experimenting a bit, so that can certainly be optimized.