The ventilation issue was the limiting factor in some 1980's experimentation in such housing in upstate NY. Houses were built to specs that were a little too air-tight, resulting in near lethal accumulation of carbon oxides, humidity/condensation issues, and in having the the kitchen window blow out if the front door was closed too emphatically.

My ancestors in Ireland used building style that involved a two-story dwelling with the livestock-cows, goats, pigs- housed in the first story, and the folks housed in the second, taking advantage of the livestock-generated convective warmth, and providing a sort of ground floor pantry of very fresh meat products. This could be adapted to urban-friendly livestock-guinea pigs,rabbits, pigeons, cats and dogs- with a suitable change in recipes. This arrangement encourages copious ventilation-the folks upstairs really WANT to have a window or two open, even in the worst weather, but occasionally the stench and squalor became unbearable...to the pigs.