That is what people who build office buildings and high-rise condos tell me.
I trust their experience and opinion more than yours.
Their explanation is that water and sewer facilities in an office building are laid out in a central core with very few branches to the restrooms and break rooms. In a condo, the lines have a much denser branch structure that needs to reach each apartment with a much higher maximum capacity on each branch.
During the commercial breaks of the Super Bowl, you might have 2/3 of the residents scoot off to the can and then flush all at about the same instant. The peak load from apartments can be way higher than anything you could find in an office building during a lunch break.
Gotta plan for these things, you know.
HVAC systems have analogous problems with centralized chillers/heaters and ventilation. The zones in an office are way too big for apartment spaces and the vents are too few to work in apartment spaces.
You want the thermostat that controls your apartment to be located three units down the hall? I thought thermostat arguments in a common office space were nasty.
All this stuff can be changed. That change is expensive and amounts to gutting the whole building and replacing everything in it. Maybe one such project will be commissioned in one city as a virtue signaling effort to the rest of the nation.
The opportunities for graft and bribes ought to be spectacular. But I would bet that the project will run late, over budget, and will never be fully completed. And there won't be another one. We will have too many other problems more important than caring what is happening to bankrupt commercial property owners or where the illegals are living.
Working on an office conversion project right now, and the points you raise are all correct. You basically have to strip out all of the Office HVAC and Plumbing, and come up with a new layout for risers that work for the apartment layouts. The facade will probably need work as well. It’s almost impossible to lease or sell a residential unit without at least one operable window.
The real reason that there aren’t more conversions though doesn’t have to do with the ducts and the pipes and the electrical service, or even the exterior wall. It’s the basic geometry of the building. It’s easy to see once you know what to look for. In office buildings, the core to glass distance can be 35-40 feet. A resi unit wants to be about half of that, because no one wants a long, dark series of rooms and then one room with a big window on one side. No one would live there willingly, let alone rent or buy it.
Long story short, converting any meaningful amount of the downtown office inventory to commercial is not going to work, ever.