Insulated old building from 1921: Conversion from gas heating

Hello dear forum.

We have been wondering for some time what we should do with our heating system in the future. Of course, I have already read a lot, but we are still not really convinced.

- The house is a well-insulated old building from 1921, a semi-detached house. Currently, heating is done exclusively with gas, the boiler is from 2010 and is serviced annually and runs perfectly.
- There is a two-flue chimney, one flue is used by the gas heating, the other is free.
- We currently use just under 11,000 kWh per year, electricity consumption is just under 2200 kWh/a.
- Our roof is a hipped roof, oriented to the east, south, and west and has no shading. To put it simply, the sun shines on it all day long.
- The house is fully basemented, and we have quite a lot of space in the basement, which has a floor area of about 40 m2. It is a vaulted cellar where you can easily stand. Slightly damp, typical for the year it was built.
- We have no underfloor heating anywhere. We have modern radiators, some installed as recently as 2017. The house has a timber frame, is masonry, the roof is very well insulated (2017), the facade was well insulated in 1993, we have wooden beam ceilings filled with slag. Almost all windows are very well insulated from 2017, only 3 are still double-glazed from 1993.

We would like to heat without fossil fuels. Currently, I would probably like a pellet heating system + solar thermal.

Does anyone have any other ideas?

Does anyone have any more ideas?

Have a room-by-room heating load calculation done as a first step. Only then will you really know if the old building is well insulated. Afterwards, think about the heating system.

We would like to heat without fossil fuels. Currently, I would probably like a pellet heating system + solar thermal.

No fossil fuels, but burning wood? How does that fit together? Solar thermal is financially nonsense. Hot water in summer that you don't need, no function in winter.

Of course, I have already read a lot, but we are still not really convinced.

Then you should have actually come across heat pump + photovoltaics ;)

This is a heat pump vs pellet topic where I would prefer the heat pump. Less maintenance, no chimney sweep. First of all, you have to consider the feasibility: Do you have a way to read the supply temperature and volume flow on your heating system? Are the new radiators type 33?

Have a room-by-room heating load calculation done as the first step. Only then will you really know if the old building is well insulated. After that, think about the heating system.

No fossil fuels, but burning wood? How does that fit together?
Solar thermal is financially nonsensical. Hot water in summer that you don’t need, no function in winter.

Then you should actually have come across heat pump + photovoltaics ;)

First of all, thanks for your answer.

So wood is not a fossil fuel, but biomass and it is renewable and from the region.

Friends of ours have had solar thermal (with gas) for 5 years and their gas heating is completely off in the warm half of the year, as the solar thermal covers everything. Of course, it is only a supplement. I can of course ask for a heating load calculation, but from experience you hardly get any craftsmen, especially not for such "vague" orders. That the house is well insulated is already clear to me from our gas consumption, which is well below average for a 4-person household – but of course the calculation belongs in there, I agree with you.

This is a heat pump vs pellet topic where I would prefer the heat pump. Less maintenance, no chimney sweep. But first you have to consider feasibility: Do you have a way to read the flow temperature and volume flow on your heating system? Are the new radiators type 33?

These are questions I can't answer off the top of my head. We do almost everything in the house ourselves, but heating is not one of those things. I will find out. I also have to check what kind of radiators they are; type 33 means nothing to me.

I hadn’t read much about heat pumps yet. You often read that they are rather good in connection with underfloor heating and usually difficult to retrofit in old buildings. A complete renovation of the house (renovating all floors) is rather not an option.