Yeah, at the core it suggests each person lends €1600 (~$1850 USD) distributed in an unofficial and impromptu way, hoping to get it all back as a home-improvement good. That has some implications like:

1. You have ~15 friends and you all have houses.

2. All of you can confidently allocate €1600 this year towards one major component of the upgrade, and believe you will benefit from it in the next ~15 years.

3. All the friends make enough money that they're confident anything going wrong with €1600 loans/debts won't cause pain or problems in the friendship.

How rich do you need to be for the mentality of that last one? AFAICT that's ~3% of yearly salary (pre-tax) in Germany.

Personally, I do not want my friend group to be tangled up in a financing scheme, and if I wanted a financing scheme I wouldn't do something half-assed that could explode into acrimony if anyone chooses (or is forced by circumstance) to exit having contributed without receiving or vice-versa.

I could understand friends having good-years helping out ones having bad-years ("banqueting" [0]) but what's being proposed really doesn't map to that.

[0] https://acoup.blog/2020/07/24/collections-bread-how-did-they...

And everyone lives in a house that they own, apparently.

You're getting downvoted, but for real this is so disconnected from what I'd say is feasible for most people. I and most of the people I know live squarely paycheck to paycheck, I can't afford to buy my friends birthday presents at all, let alone set aside that much per month just to put batteries in other peoples' houses. This feels like one of those things where the author doesn't grasp the privilege he lives with.