Recommendation digital heating thermostat

Do you deal with this professionally?

Sort of. I work in commercial real estate financing, I am currently involved in a major renovation, I have built on my own initiative, and I have a small real estate portfolio.
So, the informed layman ;)

Yes and no. I work in commercial real estate financing, am currently involved in a major renovation, have built on my own initiative, and have a small real estate portfolio.
So, the informed layman;)

And where did you get all the mentioned values from?

And where did you get the many values mentioned then?

For example from various databases. There are live user inputs on heat pump consumption in all variants. Or from personal experience (in my current 75 sqm apartment I also only need 300€ for heating - partially renovated with ETICS and new windows; previously new build 2015; now KFW 55 standard construction)

Here in the forum I read that. There's a topic here about electricity consumption. In my opinion, it is already about new buildings. Certainly bigger houses, but not three times as large.

And electricity is not getting more expensive?

Electricity has become more expensive in the past mainly due to political will, yes.
Meanwhile, the situation has shifted somewhat. For example, the increasing Renewable Energy Act surcharge is now capped. There is also recognition, even in conservative party programs, that electricity must become cheaper for the mobility transition. We will see what else comes.

At the same time, the CO2 pricing starts in 2021. Gas alone will become about 10% more expensive as of 01.01.21, triggered by a ridiculously low price of 25€ per ton of CO2. The price will rise to 55€ by 2025, then to 65€ in 2026. That’s the status today; let’s wait for the next federal election... the revenues from this levy are to be used, among other things, to cap electricity prices.

The Swiss are ahead of us there; they started similarly low but are already well above 100€/ton.
The Federal Environment Agency calculated in 2019 that the real price of a ton of CO2 is 640€. This includes consequential damages such as extreme weather, crop failures, etc.
You can consider what that will do to your gas bill in 10-15 years.
You can still "risk" a lifecycle for a new gas heating system now, but after that, these systems will become perversely expensive to operate, possibly even banned early from re/installation to manage the transition. Of course, then there will be nice subsidy programs for switching again, but I would already pay attention today to being able to sensibly position a heat pump later and design the underfloor heating/radiators for it.

My heat pump (geothermal drilling) uses 2300-2500 kWh of electricity annually. About 200 sqm, four people. Part of the electricity is self-generated, the rest is purchased at 19 cents/kWh as heat pump electricity.
But yes, an air-water heat pump is less efficient (although those are getting better all the time) and you can do more wrong with a heat pump. However, there are a few rules of thumb that you should consider when choosing your heating installer. Then it will work out.

There remains the problem of the different temperatures in the rooms. How do you handle that? I simply cannot sleep at the same temperature as I have in the living room.

Quite a bit has already been said. You design the underfloor heating so that the rooms reach the desired indoor temperatures at standard outdoor temperature and an acceptable supply temperature. There are many adjustment points you can tweak. Diameter of the heating pipes, length/number of circuits, spacing of the heating pipes, insulation, etc.

This way you can design the underfloor heating so that you have 24°C in the bathroom and then 20°C in the bedroom, but much more of a spread is hardly achievable, because then physics will throw a wrench in the works.

Also, the sun plays a role, and if the living room is facing south, you can gain quite a bit of heat. For example, I am currently sitting on the sofa with the sun shining on the back of my neck. The room temperature is 25°C.

Heating was on from midnight to six o’clock. The increase in supply temperature was about 10 degrees and was then about 32°C in the morning. After that, the heating turned off and the sun raised the temperature to about 34°C until around 10:00, which was then also distributed to the other rooms.

Now the house cools down until it is about midnight again and it starts anew.

By the way, don’t let anyone talk you out of gas. It works great in new buildings and is more robust against temperatures below zero and system faults. Unfortunately, it still happens quite often that heat pump houses are built according to a fixed scheme, and then the target consumption figures are rather wishful thinking. However, if you know what you’re doing and handle things yourself or monitor everything meticulously, then yes, operating costs are lower. But that is rather the exception than the rule.

Electricity has become more expensive in the past mainly due to political will, yes.
Meanwhile, the tide has turned a bit. For example, the increasing Renewable Energy Act surcharge is now being capped. There is also recognition, even in conservative party programs, that electricity must become cheaper for the mobility transition. We will see what else comes.

At the same time, the CO2 pricing starts in 2021. Gas alone becomes about 10% more expensive from 01.01.21, triggered by a ridiculously low price of 25€ per ton of CO2. The price rises to 55€ by 2025, then to 65€ in 2026. As of today, just wait for the next federal election ... the revenues from the levy are to be used, among other things, to cap the electricity price.

The Swiss are ahead of us here; they started similarly low and are already well above 100€/t.
The Federal Environment Agency calculated in 2019 that the real price of a ton of CO2 is 640€. This includes consequential damages such as extreme weather, crop failures, etc.
You can consider what this will do to your gas bill in 10-15 years.
A lifecycle for a new gas heating system can still be "risked" now, but after that these systems will become perversely expensive to operate, possibly also banned early for re-/new installation to manage the transition. Sure, then there will be nice funding programs again for the switch, but I would already pay attention today to being able to smartly position a heat pump later and design the underfloor heating/radiators accordingly.

My heat pump (ground probe) consumes 2300-2500 kWh of electricity per year. Around 200 sqm, four people. Part of the electricity is self-generated, the rest is purchased as heat pump electricity at 19 cents/kWh.
But yes, an air-to-water heat pump is less efficient (although these are getting better all the time) and you can make more mistakes with heat pumps. Although there are a few basic rules that should be considered when choosing your heating installer. Then it will work out.

Well, as of today, my gas will not be more expensive next year; I’ve already confirmed the next contract switch.
Your assumptions are also contradicted by the new gas pipeline from Russia.
But still, thanks for your explanations.
The problem with turnkey construction is that you do not choose the heating installer yourself. I also did not want to study to decide on a heating system.