Cost estimate house renovation year of construction 71

Solar thermal energy is wasted money, it never pays off.

Correct, but without a renewable share, you won't achieve a KfW efficiency house standard, as far as I remember. Therefore, I only chose the subsidy (20%) for the individual measures.

Your assessment is not too bad, I would say. But I wouldn’t want to turn the big energy renovation wheel either. You won’t get those costs back in your lifetime. Insulate the roof (you have to), new windows and doors, done. Whether you have to completely dry out the basement depends on the planned use. Potatoes and (non-textile) junk don’t mind, if you want a home office or hobby room it has to be dry. In my opinion, the budget for the location is also rather tight. I would completely redo the electrics, lay network cables, etc. If you chisel the grooves yourselves and possibly also pull the cables, 10k is easily doable, or even less. Solar thermal is money thrown away, it never pays off.

Thanks for your assessment!

I actually don’t want to turn the "energy renovation wheel" too much either. My problem is that there are so many different opinions about it... I like holistic approaches. A goal like KfW115 as an anchor also helps immensely. Individual measures that are then sensible for achieving the goal might be difficult to argue for on their own. From a cost/benefit perspective, for example, I estimate facade insulation rather poorly, but that is often presented as hardly debatable if you want to renovate energetically in a holistic way. So to speak, without alternatives...

Basement: yes, depends on later use. There are heaters installed at the moment and a room was used for a long time as a hobby room (possibly a home office in the future). The energy consultant advised in a first assessment rather not to heat the basement anymore and to take it out of the energy calculation if we don’t need the space as living areas. That probably needs to be calculated.

Electrics: yes, we will probably redo that including empty conduits and network cables etc. It is really well suited for DIY work as well.

Regarding solar thermal: yes, it probably isn’t worth it in itself. But as Tassimat already says (thanks also to you for your contribution), it is a possible necessary addition to the gas heating if we want to meet certain energy requirements. Will have it calculated.

If you want to use the basement as a home office, you MUST waterproof it. Otherwise, all items made of paper/cardboard/textile will mold, and the working climate will also not be pleasant. That means digging around all around and renewing the sealing all around. Then you can insulate it at the same time. I fear that will be somewhat more expensive than you estimated, although you can do a lot of the work yourself with a rented mini excavator. In my opinion, the energy consultant should be fired. If you want to use the basement as a home office, you should not heat it just because it is mathematically better... specialists like that are idiots...

The roof is also basically due, did I understand that correctly? Is it only the missing underlay membrane, or is the roof covering also 40 years old and past its prime? If it has to be redone anyway, it also makes sense to insulate there. Although if residential use is not an option at all, the floor can still be insulated. If the roof itself is fine and no use is planned, just insulating the floor is sufficient.

Then you have new windows, possibly a new roof, a dry and somewhat warmer basement (the floor slab is still uninsulated).

Insulating the facade and solar thermal systems upstairs will probably cost you another approx. 50k. You then have to calculate whether you can achieve KfW115 and a subsidy with this. I roughly estimate that it is not worth it and that you are cheaper with the subsidy for individual measures.

If you want to use the basement as a home office, you MUST dry it out. Otherwise, all items made of paper/cardboard/textile will mold, and the working climate is also unpleasant. That means digging around all sides and renewing the waterproofing all around. Then you can insulate it at the same time. I fear that will be somewhat more expensive than you estimated, although with a rented mini excavator you can do a lot yourself. In my opinion, the energy consultant should be fired. If you want to use the basement as a home office, you are not supposed to heat it because mathematically it would be better... specialists like that... The roof is also practically due, did I understand that correctly? Is it only the missing underlay membrane or is the covering also 40 years old and past its prime? If that also has to be done anyway, it makes sense to insulate there as well. Although if residential use is out of the question, the floor can still be insulated. If the roof itself is okay and no usage is planned, just insulating the floor is enough. Then you have new windows, possibly a new roof, a dry and somewhat warmer basement (the floor slab is still uninsulated). Insulating the facade above and solar thermal probably costs you around 50k more. You have to calculate whether that will achieve KfW115 and a subsidy. I estimate roughly that it is not worth it and you will be cheaper with the subsidy for individual measures.

I guess I was a bit unclear, sorry: The consultant’s recommendation for the basement was: either use it as a living space, then dig out outside, waterproof and insulate, and of course keep the existing heating in the basement. Or don’t use it as living space, then remove the radiators in the basement and reconsider the drying out because it is expensive. The roof is due, yes. 50-year-old Frankfurter tiles, underneath without underlay membrane, glass wool stuffed in which has now almost completely slipped downwards. Rafters and cladding treated with a harmful wood preservative (how severe the contamination is not yet clear, but whether one wants to take a risk there even if it is only used as an attic and lockable...).

Solar thermal energy is wasted money, it never ever pays off.

Can you specify your example calculation? Over 20 years and with scenarios for the CO2 price?

I am still looking forward to your expert advice on an important point. Two pollutant-contaminated spots in the house are known to us: the wood preservative in the roof frame and the floor covering in the basement. However, of course, there may still be issues in many other places in the house... I wonder how we should deal with these hazards before and during the renovation. Should we have a pollutant assessor inspect the house and take widespread samples beforehand? Jump in at the deep end and see what happens? Should we not handle the gutting/floor removal ourselves at all, but rather assign it directly to a company? In case of doubt, during measures, try to "build over" instead of tearing out as much as possible?