During research for this posting, it soon became obvious the best calculator features would include the following components:
- Diet - some research indicates that food choices account for as much as 30-35% of the total carbon or greenhouse gases (GHG) load. Vegan, organic and locally-sourced diets lighten your footprint, while heavy meatatarian diets increase it. A truly good footprint calculator simply cannot be missing this component, and anyone truly knowledgeable about carbon/GHG load would not miss this factor.
- Home - between homes sizes, heating and cooling, insulation, and appliance use, our homes are a major source of pollution and carbon load in our daily lives. A good calculator should consider the type and size of home, its age/insulating qualities, type of heating and whether or not you have air conditioning, as well as appliance efficiency and the use of those appliances. Some of the best calculators ask questions like how long you watch TV every day (and size and type of TV), dishwasher use, how warm you keep your house, etc. Furthermore, there should be some consideration for local climate variations; heating and cooling a home in a moderate climate, like Seattle, would require far less energy than the same in Phoenix, or Anchorage. Some had accurate, but what I consider to be poor metrics, because they require you to gather all your various utility bills for the year and input the total energy use. Aside from the tediousness of this, many renters simply would not have that information available to them.
- Land Transport - how do you get around; how many miles do you travel and how fuel efficient are your choices. The best calculators allow for a multitude of transport choices with differing fuel economies, and precise calculations of distance travelled.
- Air Travel - again, a major contributor to climate change particularly when radiative forcing is considered, and is an area that is growing much faster than overall emissions. The best calculators consider both how many flights you travel, and total distance/time travelled; since take off and landings are the heaviest fuel use, its important to calculate both numbers.
- Other Lifestyle Factors - some calculators miss this totally, but other choices we make about how often to update our clothing, gadgets, appliances, etc., and other activities like recreation choices and recycling have anywhere from a very limited impact to, for some people, being a serious source of emissions.
- Context/Misc - aside from estimating the actual carbon we emit, a decent calculator should help us to put it in context, by comparing to regional, national, and international averages. Although only a few sites did so, the gold standard here would also put our total individual carbon footprint in context of what is sustainable for the world. Other factors in the judging also included things like ease of use, options for simple versus detailed calculations, and options to calculate for one person, versus all people in the household.
However, it was also decided that no matter how wonderful a calculator it was in one area, it simply could not win the competition if it didn't cover the top four categories, eg, Diet, Home, Land Transport, and Air Travel.
Tomorrow we'll advise of the winners and best-in-breed, of the eight considered, and also point out some of the major environmental outfits who don't have a calculator or whose calculator is very poor (missing at least two categories).