Old building renovation: heat pump / solar / gas / oil

Hello,
we are going to take over an old building from 1900 in Switzerland, which is still in its original condition. That means:
- stove heating
- double box windows
- uninsulated facade
- no gas connection

Now I have the following conditions:
- for tax reasons, it makes sense to spread the investments over several years
- a new gas connection costs >> 20,000€
- night electricity costs about 15 cents/kWh, day electricity 30 cents, gas about 17 cents and oil somewhat less

The windows definitely need to be renovated - there’s no way around that.
My question now is: purely economically, the operating costs alone (without investment) of a gas boiler are already higher than those of an electric heating element (even 106% efficiency can’t compensate for that anymore).

I am currently a bit hesitant about the basic costs for a gas connection or an oil tank. Therefore, a air-to-water heat pump with a 2 cubic meter storage tank would be an idea. On the other hand, I will not be able to achieve particularly low flow temperatures in the old building since the insulation will probably have to wait and I cannot install underfloor heating everywhere.

What do you think about that? Or have there been significant improvements with heat pumps ("air-to-water high-temperature heat pump")?

I also still have some garden space. So a ground-source heat pump would also be possible.

But what do I do in harsh -20°C weather?

Regards
ALF_BE

Correct is: "Night electricity costs about 10.5 cents/kWh, daytime electricity 20 cents, gas about 11.5 cents, and oil a little less"

....
- a new gas connection costs >> 20,000€...!!!

Where does something like that exist???????????????? In Germany this costs about 2,000€.

....(even 106% efficiency doesn’t compensate for that).

Where should the 6% come from? The combustion efficiency should not be confused with the annual utilization factor. The latter is roughly 80% for gas condensing boilers depending on the share of heating/hot water.

....Currently I’m a bit hesitant about the basic costs for gas connection or an oil tank.

Understandable with those connection costs!

....Therefore, an air-to-water heat pump with a 2 cubic meter storage is an idea.

Why this storage?

....On the other hand, I won’t be able to achieve particularly low flow temperatures in the old building, since the insulation still has to wait and I can’t install surface heating everywhere.

Unnaturally high flow temperatures have a more noticeable impact due to the naturally lower seasonal performance factor of air heat pumps compared to ground source heat pumps.

...But what do I do at a crisp -20°C?

Heat with a ground source heat pump!

Best regards.

Heating with a brine heat pump was also my first thought. However, it must be assumed that this is also structurally feasible and approved by the authorities. If for structural reasons a brine/water heat pump cannot be used, the air/water heat pump is a good alternative. Even in winter, at frosty outdoor temperatures, the air/water heat pump provides comfortable warmth in a well-insulated house. It is also attractive for retrofitting in old buildings where the heat source soil cannot be used for structural reasons. Here, the existing heating system can often continue to be used while simultaneously saving on energy costs. If the insulation standard of your house is too low and thus the energy demand is particularly high, I would recommend the brine heat pump to you.

...However, it must be assumed that this is also structurally feasible and approved by the authorities.

This should apply to every solution.

...If a brine/water heat pump cannot be used for structural reasons, the air/water heat pump is a good alternative.

Why exactly this one? There are much more interesting alternatives, provided an air heat pump should be considered at all.

...It is also attractive for retrofitting in old buildings where the heat source ground cannot be used for structural reasons. Often, the existing heating system can continue to be used while also saving on energy costs.

That is likely to remain more of a seller's myth :o

best regards