Renovation of Single-Family House 1936 - Options Energetic Renovation - especially Heating

Hello everyone,

at the beginning of the month we signed a notary contract (for ) and are currently selling a property to finance it. We now have initial bids and will probably get our calculated price, maybe even a little more. In theory, we then have roughly €450-500K in capital, but we definitely don’t want to use it all.

Now we want to slowly start the renovation and are considering how it should look. We don’t have the keys yet and haven’t been back in the house since the viewing. The house is about 185 sqm (45 of which are in the finished attic calculated according to slope). It was insulated at the end of the 90s and also got new double-glazed windows at that time. There are currently two 24kw gas floor heaters from 2002 running inside.

Must:
- Electrical work
- Expose and sand floors
- Painting work
- 1 bathroom new
- 1 guest toilet new
- new kitchen including new floor there
- insulate attic as upper floor ceiling (it is quite large and covers a lot of roof area)
- insulate basement ceiling

Want:
- 2 steel beams to open up the living area downstairs
- move guest toilet from garden side to the front (pipes through basement) - otherwise it's right in the middle of the living area
- more light on the ground floor through sliding door/glass towards the garden
- terrace
- fireplace
- exterior painting
- front door
- sand and paint stairwell
- replace some of the interior doors
- possibly new radiators - see below

For these works, we roughly estimated with the architect somewhere between €200K and €250K.

I would also like to modernize the heating (independent of the expected upcoming gas prices, which of course provide even more motivation). The architect first suggested removing one of the two boilers and installing solar support on the roof. For me, it almost makes more sense (apart from potential delivery difficulties) to install something else now because the boilers are already 20 years old. But I’m unsure:

1) what options come into question? Heat pump vs. wood pellets?
2) whether it even makes sense with the building envelope? The architect said that with attic and basement insulation and partially new windows, you could probably get to about 150 kWh/m per year. Or would you have to completely redo the roof for that?
3) whether that also means installing underfloor heating? Throughout the whole house? We once looked at a house that had a pellet heating system with some normal radiators and some underfloor heating. How would that be with a heat pump?
4) how long are waiting times for these heating systems currently and to what extent would that influence the entire renovation process? If because of that we could only move in a year later, it wouldn’t make economic sense (cold rent = €1000 per month, plus two times incidental costs in that time).
5) if the waiting times currently make it uneconomical, does it make sense to prepare a modernization already? E.g., laying the underfloor heating first and only connecting it later?

Thanks for the input :)

It can only come down to a heat pump. Read up a bit on wood pellets, then it’s no longer a question. (Fine dust, CO2 just as bad as with oil, delivery problems, prices, overexploitation...)

Heat pumps generally also work in old buildings. Of course, you can save on operating costs if you use underfloor heating and insulate beforehand. But it will work without that too. And of course, it makes sense to do everything before moving in.

And yes: you can first install underfloor heating and if necessary wait a little longer for the heat pump. As long as the boilers are running, that’s no problem. I retrofitted underfloor heating in an occupied state and would not recommend that to anyone. What you must not forget: underfloor heating increases the value of the property AND also the living comfort. It is simply the much more pleasant heat. No circulation of air and dust, no cold feet and warm heads. Also, you gain a few square meters of living space. And those are worth something too...

I wouldn’t mix (radiators and underfloor heating). If it gets difficult in some rooms, walls and ceilings also work. And if so, then design it so that no different temperatures need to be run.

How heat pumps work is explained in tons of other threads here anyway. Just read through the forum a bit. It’s always the same.

Insulating a roof should always be at the very top of the renovation list. Even before the windows. If you tackle that, it usually also pays off to fully equip everything with photovoltaics at the same time. You’ll need to do that sooner or later anyway, and it’s cheaper if someone is messing around up there anyway.