Then put restrictions on it - pass a law that allows you to convert commercial to residential during X number of years and for that converted commercial to have slightly laxer requirements than standard residential housing. Don't allow new residential construction to skirt the regulations and put a time limit on the law to keep property developers from simply building commercial with the off-chance of being able to convert it to residential if the market for commercial real estate doesn't rebound.

If only making laws was as simple as adding if statements in computer programs...

In the real world, you have millions of agents try to game every law and bend it into their advantage in some way.

> You make this legal and tomorrow every RE developer stops putting in windows

This sounds like new housing supply. I'm failing to see the problem. Developers still have to sell the apartment, after all.

>This sounds like new housing supply. I'm failing to see the problem

The problem is the new housing supply was always imminent - only now, it's windowless, all because developers can increase margins by 1.07% and shorten build times by a day.

Except people will pay extra for windows...