The Carbon Footprint website offers calculators for business or home and contains sufficient details to give a good sense of the actual impact for a particular building.  The site also contains tips for CO2 reduction, carbon offsets, offset standards and other useful information.  There are many organizations that offer carbon offsets, so we recommend contacting more than one organization to find the best fit and price.  But first, it's important to know the carbon footprint so that the offset requirement can be determined.