[yayachiken]

> Source?

Assuming an economic lifetime of 70 to 100 years for new buildings is industry practice based on standards like DIN 276. You can find those numbers (with some variation) on pretty much every web page dealing with economics of building, for example here: https://www.bauprofessor.de/wirtschaftliche-nutzungsdauer-ge...

You can also approximately extrapolate that number from the source I have given you. (Which is based on a survey by the federal government of Germany) If approximately 50-60% of houses are older than 50 years, then assuming a approximately linear to progressive attrition curve you will get a number around 100 for the average lifetime.

Of course a long tail exists, but 1. I was talking about economic costs, people might just like their houses and renovate even though it is financially not worth it, and 2. after 100 years the historical protection (Denkmalschutz) gets more and more relevant and is a whole different set of regulations.

[valenterry]

I think you misunderstand what "economic lifetime" means here. It is mostly relevant for tax purposes.

In other words: if you build a house for $X and live in it then for tax purposes it is assumed that (on average) after a 100 years you must have been spending $X for maintenance so that you can sell the building for $X. If you have spent more money, then you can't deduct that from tax (exceptions exist).

Or in yet other words: if you don't spend anything for maintenance then after 100 years (on average) the building will be worth nothing, meaning that it will cost the same to rebuild it compared to fix it.

But since most people maintan their buildings, i.e. fix the roof when it starts leaking, fix the doors and windows when they break or are not airtight anymore etc., buildings are much older than 100 years. 100 years is the _minimum_ time before it's even worth to rebuild on average.

[yayachiken]

These maintenance tasks are exactly what this discussion is about.

You will do major work on roof or facades every 50 years or so. This is exactly the opportunity where you pretty much get insulation for free.

After 100 years the house will have been all but structurally rebuilt once, just for upkeep reasons. You perform energetic renovations together with the upkeep tasks.

And when the house is old enough, the monument protection agency will even force you to do it by that time.

[valenterry]

Let me quote you:

> The expected economic lifetime of a building in Germany is approximately 100 years. Which means that on average, the house will be torn down and rebuilt after at most 100 years, because additional upkeep would not make economic sense.

This is just wrong. An economic lifetime of 100 years does not mean that the (on average) buildings will be torn down and rebuilt after at most 100 years.

And I have already explained why that is. Please read my post again and try to understand it.

> You will do major work on roof or facades every 50 years or so. This is exactly the opportunity where you pretty much get insulation for free.

No. This is also just wrong. Yes, when major work on roof or facades have to be done, this is usually the best opportunity to also improve insulation. But you don't "pretty much get insulation for free". Unless you have a very uncommon definition of "pretty much for free".

Mind that I'm not saying that insulation isn't worth it or anything like that. I'm just pointing out that some parts of what you are writing are wrong. And the sources you cited are not supporting your claims. That's all.

[yayachiken]

Please don't forget that my claim is in the context of somebody else claiming that insulating all housing in Europe would at least take 100 years.

Now you are literally redefining the terms I use and then quoting them back to me to argue your new semantics, are you serious?

On average, a house is considered to last 100 years in Germany. Call it economic lifetime or whatever else you want. I still stand by that claim, as it is common knowledge. I quoted specific numbers on the housing stock which are consistent with that claim (though no proof of causation, as there are plenty of reasons why we have a lot of new stock, for example in general rising number of buildings.)

And of course the insulation is not "for free", but the additional costs are usually worth it. I also mentioned that many people decide irrationally because they do not want the work associated with planning and ordering the maintenance to be performed.

None of this matters to show that the above mentioned claim how long renovation of the current housing stock will take is completely out of the world.

Note that I am by no means a civil engineer or architect, but following the discussion and researching the topics associated with the Energiewende in the different sectors for over a decade now. I may still well be wrong in this instance. But you won't convince me of that if you try to prove me wrong on semantics and just asserting that I were intellectually unable to understand your arguments. So please also state some relevant facts and sources to support your claims if you want to try further to convince me, otherwise continuing this discussion is probably a waste of time for me as we both will probably not learn anything new. Thanks.

[valenterry]

> But you won't convince me of that if you try to prove me wrong on semantics > (...) > On average, a house is considered to last 100 years in Germany.

First please define what you mean by "last" so that we share the same semantics and then provide a source on this. And if you mean that a building will have been destroyed and rebuild after 100 years on average then I doubt this claim - after making such a strong claim I think it's up to you to provide evidence.

> I quoted specific numbers on the housing stock which are consistent with that claim

Are you referring to https://www.bauprofessor.de/wirtschaftliche-nutzungsdauer-ge... ? Because if you do, then again, you misunderstand what they are talking about. Also, don't forget that average house-ages are misleading due to WW2 where a lot of old houses got destroyed. So you can't e.g. just take the average age of existing houses, that doesn't work.

> And of course the insulation is not "for free", but the additional costs are usually worth it.

Look, I agree with you - but the way you said it before is so exaggerated and easy to misunderstand that it's no wonder that you are getting these kind of responses. This is a very emotional topic and it's good to try to adjust the language accordingly.

> I also mentioned that many people decide irrationally because they do not want the work associated with planning and ordering the maintenance to be performed.

It's easy to call someone irrational - but why do you think they don't want this work to be performed. How comes? I doubt that you assume they want the planet to die, so what do you think are their reasons?

[yayachiken]

> First please define what you mean by "last" so that we share the same semantics and then provide a source on this.

Le me just try to give a definition, "lasting" for me means that you only do maintenance and rework that you would still consider the building year to remain the same after you are finished.

Also the semantics of the term "lasting" were not the issue, the issue is that you do not my sources because you find the term economic lifetime and its definition unacceptable.

> Are you referring to https://www.bauprofessor.de/wirtschaftliche-nutzungsdauer-ge... ?

No I mean my number that approximately half of housing buildings are younger than 1977, so approximately 50 years.

This refers to a survey by the government, see box on bottom: https://www.bundesregierung.de/breg-de/themen/klimaschutz/kl...

Someone else in this thread posted a similar source from ourworldindata which has a bit older data but also shows the same trend.

The latter source also has a more detailed breakdown of building years. But even the former source mentions 1977 as its index year which already alleviates the external effects of WW2, people did not just live without houses for 30 years, the lost housing of WW2 was mostly rebuilt in the 50s.

Also, I do think that your claim is not valid. I do understand that the source I gave for economic lifetime, and also the norm I quoted is acting with fictions required for taxes and accounting reasons. The thing is: These fictions are intended to reflect reality. So I don't get why you are so hung up on where these calculation models originate, as they are specifically designed to reflect reality. If they were outlandish, especially when lifetimes on average are longer, these calculation models would absolutely be changed because then the state earns more money due to lower depreciation. If it was the other way around, the calculation model would be challenged in court.

Of course there is no natural law that a house collapses after 100 years. But not only in architecture, in all of engineering, it usually does not make sense to design for an infinite lifetime. If you double the lifetime of anything, it will cost a lot more money. Why would you spend more money today to build a house with better materials, when you don't even live to see the rewards in the form of lower maintenance and renovation costs in a 100 years. By extension this applies for the amount of money you want to spend in maintenance, at least for natural persons. In many situation it makes sense to simply use up the bound capital.

Now this leads to the following:

> It's easy to call someone irrational - but why do you think they don't want this work to be performed. How comes? I doubt that you assume they want the planet to die, so what do you think are their reasons?

As an anecdote for illustration, my grandparents still heat with oil, but the heater soon needs to be replaced. My grandparents are absolutely stubborn in that they want to replace it with a completely new oil-based heater. The literally only reason is: They are old and don't want to try out something new, even if it is functionally exactly the same (like a wood pellet heater). I literally offered them to pay 100% of the new heating system (reversible heat-pump because heat is one of the primary killers of elderly people and I would like my grand-parents to be around a bit longer...) after they bought heating oil on the ATH this spring and they still disagree. There is literally no economic incentive of looking the gift horse in the mouth, and they are unable to offer any other rational explanation.

You may also skimp on maintenance because you think "I am going to die soon anyways". Or people are planning to be living in a large 200 square-meter mansion with 3 stories until they are 90 when in reality they sell the house at 60 and suffer the loss of value when re-selling due to insufficient maintenance.

And some people just want to live in their house and don't give any thought to it until there is an emergency. Then people will have expensive repairs and still won't think twice about changing their behavior.

Some small house owners skimp on maintenance because they bought their houses as an "investment", and they are dependent on rent income to reliably subsidize their life. Even when the income could be higher in the future with some investments and quickly ROI, they won't accept saving up for it and taking on the economic risk.

Even for institutional housing owners it makes sense to tear down units eventually, even if it is just to get rid of the long-term tenants who make larger renovations annoying to impossible.

There is a lot of small house-owners and in general, most people are just really bad at basic accounting. This is also a big reason why the housing market in general is such a pain in the ass.

[dahfizz]

> Assuming an economic lifetime of 70 to 100 years for new buildings is industry practice based on standards like DIN 276.

Sure, but that wasn't the standard 100 years ago. There are plenty of existing houses that are 100+ years old that will continue to stand for at least another 100 years.