I have no idea what the toilet paper bill is for a large office building, or how much they might use per person on average, but I'd like to know, because toilet paper has been described as one of the greatest excesses of the modern age.
Fortunately a Japanese company has invented the "White Goat Machine". This contraption converts used office paper into toilet paper.
The machine stands 1½ meters tall, weighs 600kgs, sells for a mere $130,000, and can regurgitate a toilet roll created from 40 sheets of A4 in a mere 30 minutes. That makes for some very expensive toilet paper. Assuming you aren't stockpiling them, or selling them as a new venture, you might just break even after a quarter of a million rolls, so long as you don't factor in the electricity needed to run it.
However, you may not have to, because the White Goat Machine could be self-powered. By installing an in-house system to capture the office's bio-waste, then passing it through a bio-digester to harness the methane, it could provide fuel to generate the electricity required to power the White Goat.