Also, I thought of another thing you should factor in: restaurants. They're incredibly wasteful with food. With no office workers, many restaurants (especially around offices) have drastically fewer customers. You'll need to include the carbon savings from some percentage of the food that goes to waste.
Yes, I was just being conservative. The savings on the office side would be much lower, because as I said, offices are more efficient than homes. Plus, most offices would not close if people work from home.
As for restaurants, you are going into second and third order impacts. Why not calculate the savings from all the dry-cleaning that doesn't happen because people can work in their sweat pants at home?
Yes, that's what systemic change is, and you appear to be presuming (with your mocking jab about sweat pants, give me a break) that it's irrelevant to study second and third order effects of large social changes. That's not a very credible perspective to have.