Construction costs are currently skyrocketing

Does it really bring that much efficiency gain? If we assume similar living areas per unit and comparable standards for single-family houses and multi-family houses, then I am skeptical. Flooring is installed based on area, regardless of the building envelope. Plumbers and electricians are also quite independent of whether they work in a single-family house or a multi-family house. In shell construction, you need somewhat fewer exterior walls, but some interior walls are more complex because they separate living units. I see a few synergies regarding price (volume discounts, fixed costs spread over more units, one large heating system is cheaper than six small ones,...) but I don't automatically see faster construction times. I see the bigger leverage regarding construction times rather in replacing reinforced concrete construction with something faster.

Of course, multi-family houses can be built more efficiently with good planning: extensive use of large precast parts in series production and of KS panel elements with more intensive use of machines makes much more sense here compared to single-family houses, the building areas are used much better. To improve the housing market in cities, this is the only option. Single-family houses are completely uninteresting here and, due to urban sprawl, even worsen traffic problems.

I see someone has read the DPA report about modular construction that is currently being covered in all the media. The question was not whether it is possible to build more efficiently (it is), but whether simply switching to multi-family houses brings a significant efficiency gain. And my opinion on that is definitely no. The hype about modular construction seems to come around every year, and ironically the cost advantage does not appear to be big enough for it to have established itself so far. In practice, it is probably not that simple, just as in reality a prefabricated house builder is neither faster nor cheaper than a solid construction of the same standard.

And as far as traffic problems are concerned... single-family houses appear quite far down the list of actual problems. Much more important would be, for example:
- Not concentrating companies but distributing them across the country
- Designating building land where people live and work to reduce commuting distances
- Appropriate infrastructure for cycling, cleared bike paths in winter
- Appropriate network coverage and scheduling in public transport where routes cannot be adequately covered on foot or by bike
- Eliminating bottlenecks in car traffic where necessary (and no, if you create sufficiently good alternatives, that does not automatically generate more traffic)

Even in rural areas and single-family house neighborhoods, more trips could be made without a car if people did not ride their bikes in the middle of the country road after only a few hundred meters

I see someone read the DPA report about serial construction that is currently being broadcast in all media.

Exactly. Henry Ford the dilettante had no idea.

I believe there is a difference between building a car and building a house. And by the way... the counterpart to Ford is the Plattenbau. Dozens of identical houses in one spot, while Ford was "any color as long as it's black." Today, nobody really wants that anymore, neither the people who live in them nor the people who have to look at the uniformity. Today, what is rather desired is what you also see in the automotive industry: one model with hundreds of options. This then leads to a combination that takes away a larger part of the advantages again: Die Wolfsburger haben mal nachgerechnet: Im vergangenen Jahr hatte VW in Deutschland fast 84.000 Golf verkauft. Davon hatten mehr als 58.000 unterschiedliche Konfigurationen. „Gerade mal 400 Golf waren identisch, von den unterschiedlichen Farben mal abgesehen“ [..] „Das heißt: Wir bauen Unikate.“

Der Aufwand dafür ist groß. Schließlich müssen für die unterschiedlichen Ausstattungen unterschiedliche Teile an die Bänder gebracht werden, an jedem Fahrzeug sind andere Montageschritte nötig.

And that corresponds rather to what you already get today from every prefabricated house builder.

That means: We build unique pieces.

Nice marketing gag. Unique feels better for the buyer than mass-produced goods. They are still cars off the shelf. You don’t really believe that because of special equipment the car is taken off the line and the accessory elves conjure the seat heating into the seat by moonlight with the golden wrench. Series production in houses does not automatically mean DDR panel construction according to formula F, and standardization does not mean everyone has a black toilet bowl.

Recently, I think the question came up here about the changes in photovoltaic systems. There is a two-page article about it in the current Finanztest. :)