[wing-_-nuts]

Replacing unused office space with dense multifamily housing would benefit the climate long term as city dwellers have a much lower carbon footprint. Not to mention that they've gotten good enough building with engineered timber that they can safely build midrises with the stuff. No need for concrete.

[cal_dent]

but by demolishing you're releasing and generating a ton of embodied carbon for a likely relative limited output of residential homes on the other side (because the economics doesn't stack up). I'd contend that the trade off is as simple as you're suggesting.

[wing-_-nuts]

Razing buildings generates no more carbon than what is required by the machinery to demolish it and cart off the debris. I'm starting to question whether you're speaking in good faith