Energetic house renovation: our experiences

Hello, as described, I would like to share our experiences with our house renovation, insulation, and more.
First of all: It can be worth it.
Why do I say can? Because the topic is complex and cannot be generalized.
I’ll start: Nine years ago, we bought a semi-detached house built in 1935, with double-walled hard-burned brick masonry (probably lasts a thousand years).
Double-glazed plastic windows. During the first work phase, we removed the cellar insulation (granulate) and installed/ had installed 15 cm of Styrofoam insulation and underfloor heating on the ground floor. Later, the roof was due; on the shingle roof, a lightweight metal roof was built. I made sure (important) that the roof overhang was extended towards the gable by about 30 cm.
Two years ago, we insulated the exterior walls, due to structural conditions only with 8 cm mineral wool boards (I think better than Styrofoam due to permeability). My advantage: I had done this elsewhere before under supervision, it proved reliable, and so I was able to do everything on my own. Therefore, costs for about 80 m2 were around 5000 euros including material and scaffolding costs for four weeks. At the same time, we replaced the old gas heating system with 80 liters of hot water with a new condensing boiler, hydrogen-capable, with an included 20-liter hot water boiler (more on that later).

Heating costs before: 20,000 kWh. Now for two years about 7,000 kWh per year. If you perhaps consider that the last winters were not so cold, then that is roughly a saving of at least half. Unfortunately, since both works were carried out in the same year, I cannot say which savings are due to the insulation and which to the heating system.

But in our case, it was definitely worth it; in a few years, it will have paid off.
I can recommend insulation anyway, just saying, who goes outside without a coat in winter?

About the gas heating system: We also considered a heat pump. That might be better in the long term. But first, we had no experience with it. Second, the costs were almost three times as high. And now I wonder, when I read that in other countries, Denmark, United Kingdom, it costs only a third of what it does here in [D], then something is off if that’s true.
I don’t want to say more about that here; everyone can form their own opinion. By the way, electric cars in other countries also cost only a fraction of what they do in Germany.

I’ll stop here for now. If you have questions, feel free.

Best regards, Benno

So that someone finally answers: The fact that insulation leads to a reduction in heating costs has probably been known for a long time and is also intentional, just like wearing warm clothing in winter. In other countries, different prices apply, as is well known from many areas, such as food prices here having been cheaper than elsewhere for years.

I assume that your property is located in East Germany. The purchase price in 2015 was probably still reasonably affordable. The renovation also sounds very sensible.

The result counts, and if you save more than half of your energy costs, the energy-efficient renovation was indeed successful.

Those declared dead live longer, and the same will happen with the gas heating system. I do not believe that it will ever be operated with hydrogen. Hydrogen is already doomed to fail today, as are heat pumps.

This may make sense in new buildings but not in old buildings like yours. Perhaps the hot water production could have been realized with a heat pump, but even there the gas boiler is more efficient.

I don't want to say more about it here, everyone can form their own opinion. By the way, electric cars in other countries also cost only a fraction of what they do in Germany.

Actually not in other countries. There are basically only the Chinese - but their car and battery industry is unnaturally boosted with billions, and please don't ask now what the workers earn and how they are doing.

To be specific.

An employee in China earned an average of 120,698 yuan per year in 2023. This corresponds to around 16,810 US dollars per year, based on the year-end exchange rate of the Chinese renminbi to the US dollar.

The statement by is false.

There are mainly only the Chinese - but their car and battery industry is unnaturally pushed with billions, and please don't ask what the workers earn and how they are doing.

Many workers in China have achieved a small amount of prosperity. Prices are significantly cheaper than in Germany.

And to put it into perspective, my annual salary is only 21,600 euros. Only I have significantly higher prices. Is the Chinese worker really doing that badly?

The statement by @nordanney is wrong.

What exactly is wrong?

Is the Chinese worker really doing that badly?

I didn't say that. But the skilled worker in Germany, who assembles a car in Wolfsburg, earns multiple times more than the worker in China. It follows that labor costs are massively lower than the German ones. And from that follows that the car can be produced more cheaply in China.

The statement by @nordanney is wrong

Thus the statement is correct with regard to the cost situation in China. Are you by any chance a new boxwood?