A friend told me about the post. Thanks for the kind words. Glad you’ve all found it useful.
Love the book by the way; it's what I wish I'd had when I was looking to buy my first home. I'm going to be gifting it to a few people in my family over the next few years.
I'm halfway down that road, having completed a high performance remodel in the Bay Area, and contemplated a career shift into some adjacent field.
High performance building is not as organized a movement here, but instead a patchwork of architects, contractors and consultants that I had to assemble for my project. Assembling a team that was willing to work in a high performance modality was probably the hardest part. It's still unfamiliar to many customers and professionals.
I also did a good amount of the high performance work on my house, so I got to know the principles and practicals pretty well. It was a lot of work, but I enjoyed the process and the learnings (and living in the result).
The bulk of the work is wrapping the building in 25cm of rigid foam exterior insulation, replacing windows and making sure that they are fairly air tight. They aren't adding mechanical ventilation, as installation would cause too much disruption to residents who are living there. Heating systems are being upgraded to newer units if they are old and inefficient (still powered by gas or district heating, no heat pumps).
The main issue with older buildings is often you want to maintain the 'character' so wrapping the building in external insulation and replacing the facade isn't always an option. However if you have a building made of masonry this is the best way to insulate it, as the masonry then acts as a thermal mass to keep temperatures inside more stable (in both hot and cold weather). These apartment blocks were ugly concrete that nobody wants to ever see again though, so it's not an issue here :-)
Article in Polish, but worth translating or just looking at the photos: https://www.money.pl/gospodarka/w-tym-miescie-nie-martwia-si...
Shortly: insulation, new windows, solar panels, heat pumps (heating + warm water).
They do not show "before" photos, but I found some similar building before renovation on the same street: https://www.google.com/maps/@51.3586963,21.5793371,3a,75y,16...
They mention 90% savings in heating costs, which apparently pays off the debt they had to take to make the upgrades.
Hmmm, like the worst possible idea (air tight + not adequate ventilation), the early (10-15 years ago) "Class A" or "Class B" new buldings made here without appropriate ventilation have given lots of problems (humidity/mould).
The only possible remedy being daily manual ventilation, i.e. open windows for 10/15 minutes every single day (but many people won't or cannot do it).