There are a host of calculators out there to help you or your office determine your impact. Once your impact is known then create a goal of how you would like to reduce it. Here are a few of my favorites to get you started:

Global Footprint Network: A good overall calculator on general green footprint

Household Savings Calculator: Developed by the NRDC to track home energy savings

Water Calculator: Developed by H2O Conserve this measures water consumption.

Xerox Sustainability Calculator: A great calculator that measures the overall  impact a company’s printers and copiers have on the environment.