I always thought this was true; you convert unused office space into housing and solve several problems at once:

There’s an appealing simplicity to the idea of converting office buildings into housing. The premise suggests cities could solve two problems — an office glut and a housing shortage — at once. In the process, they could limit the waste of demolition, create new homes with minimal opposition, and renew neighborhoods without radically changing how they look from the sidewalk.

As it turns out, it’s difficult. Pre-war office buildings are easier to convert than newer steel-and-glass boxes with massive floor plans enabled by air conditioning and bright lighting. Emily Badger and Larry Buchanan explore how office buildings from different eras are converted into apartments.