Actually what's even better than water for you orchid is ice, I know it sounds a little weird but if you put a few ice cubes in your orchid every other day it will make the plant life for a long time. My mom and I have been doing this for year, and we have found that this is the best way to 'water' our orchids.
Well this depends on hot warm and dry it is in your office. This being said usually about once a week is best. The best way to do this, is to place the pot into a pot of water and allow to sit for 10-15 minutes, to allow the wood chips to soak up water. Then make sure that there is no standing water remaining, or else you may get root rot. Orchids need air flow on there roots.