FitPlanet defines an event's climate footprint as including all direct and indirect greenhouse gas (GHG) emissions produced in the planning and production of the event. For more on your Climate Footprint see Chapter 2 of the Handbook.
Measuring the climate footprint of an event is comprised of two things:
For the typical event, CO2 emissions from travel accounts for the lion's share of the climate footprint. For a small fee, FitPlanet can calculate the total emissions of your event and can also advise you on reduction and offset options.
Athlete, staff, sponsor, volunteer travel can be estimated as the round trip from the place of residence to the event site. The sum of the total miles driven is roughly equivalent to the pounds of CO2 produced from travel. That is, for every mile driven in a 20-mile-per-gallon car produces 1 pound of CO2. If people are flying to the event, the CO2 emissions per mile is slightly higher. Divide the total pounds by 2,000 to get total tonnage of CO2.
Emissions from event operations can be calculated in a similar fashion - total miles driven by all the vehicles used to produce the event - pace car, logistics and equipment vehicles, etc. Plus fuel used by the portable generators.
If you're drawing power from the grid for the event there are portable power meter you can use to gauge total kWh used. The conversion to pounds of CO2 is approximately 0.537 kg CO2/unit or 1.18 lbs CO2/unit, as estimated in a 2008 report by UK-based Carbon Trust. For many events, the power drawn from the grid is inconsequential. For large events, however, that also have a one- or two-day expo, you should make the calculation.
Once you've measured or estimated each category of emissions and converted them to pounds of CO2, sum the figures for total emissions.