ᐅ Order of Renovation for a Single-Family Home

Neubau2020 schrieb:

Well, can you really say that so generally?
From April 1, 2021, you still get 7.81 cents per kWh of electricity, as long as there is some left after self-consumption.

With a 10 kW system, you receive about 900 € (euros) in feed-in tariff. It costs around 11,000 € (eleven thousand euros). So, it pays off after almost 12 years.
With 30% self-consumption, you’re looking at 8 to 9 years. With an electric car, maybe after 6 years.
I don’t think that’s a bad investment.

Neubau2020 schrieb:

I’m not a fan of external wall insulation due to the high costs. We basically want to see if we can achieve an efficiency level just by upgrading windows and doors and insulating the basement ceiling.

Especially with older buildings (your house is borderline in this regard), there are frequently reported issues when installing new windows without improving external wall insulation, for two main reasons:

1.) Increased airtightness reduces air exchange
Modern windows are as airtight as plastic bags. This requires strict ventilation discipline—something many occupants struggle with—leading to increased humidity. Uninsulated walls are cooler than well-insulated ones, making it more likely for the dew point to be reached, which can cause damp walls and mold growth.

2.) Moisture no longer condenses on the windows
The effect described in point 1 is disproportionately intensified if the triple-glazed window provides better insulation than the uninsulated wall. In that case, the window’s interior surface would be warmer than some parts of the interior wall, and nearly all moisture would then condense on the wall instead. During the heating season, the window should always be the coldest spot in the room, as condensation there causes the least damage and is also immediately visible.

In the 1980s, there was sometimes some insulation applied (for example, 6cm (2.4 inches) styrofoam). This might slightly reduce your problem, but you still need to keep an eye on it.

We renovated a 1970s end-terrace house from the inside last year.
We started with a complete gutting of the interior. Then the major work followed, like removing walls, taking out the plumbing, chasing walls for new electrical wiring, and so on.
After that, everything was rebuilt. The windows were replaced fairly early on, as we gradually moved towards the "rebuilding" phase.
By the way, doors were installed almost at the very end. I find it much more practical to have the flooring laid first, rather than fitting the flooring around the door frames afterwards.

We chose triple-glazed windows and left the facade as it was. So far, no issues; we also make sure to ventilate regularly.