[jdross]

Cheaper to tear down commercial RE and rebuild multi-family than to attempt a conversion. Floor plates made of high tension steel can’t be broken up for replumbing, usually you’ll want or need elevators & interior courtyards needed for lighting. There are very different water & electrical requirements

Maybe there’s a creative way to do low-income housing meaning only a window or two in the whole unit, no individual HVAC control (set by building) lots of artificial light, and someone more knowledgeable than me would need to explain the power & plumbing tradeoffs. Maybe you could basically replumb & wire on top of the floorplates, taking a few inches from ceiling height?

[m0llusk]

There are important exceptions to this. Old industrial era commercial buildings often have large spaces and big windows that make them relatively easy to convert. This is why lofts as a form make sense while also being desirable. Much of the cost of converted units comes from the high cost of acquiring the property, but that is less of a problem if the properties lose their value or are possessed by the government. And it is worth remembering that all properties are depreciating assets that get rebuilt or refurbished every 15-45 years or so on average anyway.

[johnyzee]

There are solutions that redirect actual sunlight from outside, into dark interior spaces. They use them in many modern metro stations, and they work pretty well to get the feeling of actual overhead windows. AFAIK some of these solutions successfully channel almost the entire spectrum of real sunlight. I always feel that this is way under utilized - I could hardly name a building that wouldn't benefit from additional sunlight in some of the interior spaces. The systems are currently quite expensive, so that's probably part of it.

As for plumbing, like you I also speculate if they could not just do a raised floor, or possibly inside/along walls, to increase the reach. They already do this in some renovations of very old buildings where they want to create a large central kitchen (resulting in almost horizontal plumbing that clogs like nobody's business).

[hindsightbias]

Communal housing floors. Facilities and shared kitchen in center core. Modern buildings already support wide flexibility for walling working areas.