When/if we finally buy, we're looking at a rural, passive self-build where we can work remotely. The cost is about the same as a town house these days.
There isn't any technical reason why you couldn't put in proper isolation between floors or walls, aside from the fact it would slow down construction and be expensive. Proper insulation (both acoustic and thermal) also makes rooms smaller in a given footprint which is an issue for marketing.
This is definitely ideal, but is it achievable (in average, not for any individual) in larger cities even if they are built for walk/public transit?
I don't have much experience in Europe, but I knew in Tokyo, which probably has the best public transit in the world, the average commute time is one hour. This is obviously an extreme example as Tokyo is a megacity, but I think majority of people cannot live 25 minutes from their work for any cities that have 1M+ populations, regardless how the city is built.
I generally agree, though in cities like Paris you can get close. But 1M+ is very big by European standards. There are only 34 cities on the entire continent that fit that description [1], and there are multiple capitals [2] half that size (Dublin and Lisbon each have around half a million inhabitants).
Once you get down to ~300k or fewer citizens commute times drop a lot. That's really how the vast majority of the population lives.
1: https://en.wikipedia.org/wiki/List_of_European_cities_by_pop...
2: https://en.wikipedia.org/wiki/List_of_cities_in_the_European...
If you look at the population of agglomerations (some cities in Europe have ridiculously small limits - Paris is fifteen times smaller than London), you see than London (14,800,000) and Paris (11,400,000) are a bit less populated than the the biggest US cities New York (22,100,000) and Los Angeles (17,700,000) but slightly more than the third Chicago (9,750,000).
The next biggest agglomerations in Europe, Madrid (6,550,000) and Milan (6,200,000) can be compared to Houston (6,750,000), a bit less populated than San Fransisco (7,850,000).
Then you have Berlin (4,725,000) which is close to Seattle (4,425,000) or Phoenix (4,700,000).
Most people use public transportation, and that's usually a 5-10 minute walk to/from the station on each side, and changing trains once or twice. Among my peers, it's usually 30-45 minutes with public transportation. Half that by car, if they don't work in the inner city.
In the East Bay you can start to approach reasonable but if you're working in the South Bay, your commute won't be reasonable and access to the city for recreation may not be great either.
However I do like living 3 minutes from the next supermarket, and 20 minutes from the city center with all the shop, and 25 minutes from my work (all distances by foot).
I would love to have all the advantages without any of the disadvantages, but at least around here most people prefer living closer together over commuting longer distances.