Single-family house 140m² KfW efficiency house 55 achievable through insulation and air-to-water heat pump?

Is 28° a targeted standard value or just an example?
I understand from this that the same spacing should not simply be laid as a standard, but rather the spacing must be determined for each room. However, it should be kept as small as possible to save heating costs (lower supply temperature)?

It was an example. Currently, the trend is towards 30 degrees supply and 26 degrees return.
The correct underfloor heating planning must take the following things into account:

[*]desired temperatures in the rooms (08/15 is 20 degrees everywhere)
[*]room-specific heating load calculation
[*]number of heating circuits
[*]length of the heating circuits (e.g., 1x160m or 2x80m ==> the latter is significantly better)
[*]flow rates
[*]installation spacings (I ended up with a mixed range of 5/7.5/10cm for myself)

Each point depends on the other points.

Isn’t this only relevant when the heating is put into operation? What influences does this have during construction?

Hydraulic balancing must be considered directly during planning (length of heating circuits, flow rates...) and after installation, the heating system must be put into operation as planned.

Who would I commission if I want the heating to be set as well as possible, if not the heating installer?

Planned or adjusted? You only find the best possible settings during live operation in winter (you will probably find the setting that suits you best by the second heating season). Because the settings are individual, the heating installer provides the framework. But whether the heating curve needs to be adjusted slightly, you only find out when you live in the house and easily change the heating settings yourself. For example: In the transition period, the heating switches off too early because it is already warm during the day but still cold at night. You have to (or should) figure that out for yourself. It’s similar to adjusting colors, contrast, etc., on a TV. Fine tuning.

Thanks already for the detailed contributions here :) They really help to get into the topic

The correct underfloor heating planning must take the following things into account:

Doesn't the energy consultant also have to pay attention to something like that? So that, as you also write, the heating can be operated efficiently?
What else do you pay so much money for :D even if you get half of it reimbursed.

Thanks already for the detailed posts here :) They really help to get into the topic

Doesn't the energy consultant also have to pay attention to something like that? so that, as you also write, the heating can be operated efficiently? What else do you pay so much money for :D even if you get half of it reimbursed.

He just has to ensure KfW55. If it is associated with 500 € higher electricity costs per year, then so be it :)

Doesn't the energy consultant also have to pay attention to something like that? So that the heating can be operated efficiently as you also write?

See KFW 55 is KfW 55... If he works properly, he of course also looks at such issues or gives tips. But he is not primarily hired for that.

He just has to ensure kfw55. If it is associated with 500 € higher electricity costs per year, then so be it :)

Crazy! o_O In my strawberry world, I thought this person would look everywhere energy can be saved! And would automatically consider such savings purely through the execution of measures.

In my Strawberry World, I thought this would look everywhere where energy can be saved! And would automatically take such savings purely through the execution of saving measures into account.

The Emily Strawberry World only exists on TV ;). Aside from that, the biggest factor is the residents. Anyone who wants 24 degrees and at the same time always fresh air through tilted windows will have horrendous heating costs even in a KfW40 house. Those who are fine with 20 degrees and controlled residential ventilation have low heating costs in the efficiency house. But yes, it would be nice if all energy consultants would look not only at the bare numbers but also at the implementation.