While carbon footprints are the most common measure, other measurements do exist. Probably the next most common approach to measuring human energy consumption is in terms of kilowatt hours. The idea is to compute the amount of energy humans consume in all their activities and express that figure in kilowatt hours. One kilowatt hour is the amount of energy that a one-kilowatt light bulb will draw if left on continuously for an hour.
Energy consumption varies widely around the world, with the developed Western countries consuming far more kilowatt hours than other countries. According to an article in The New Yorker, India averages 1,000 kilowatts per person, and China averages about 1,500. European countries are at about 6,000. The U.S., by comparison, averages 12,000, as does Canada. Furthermore, kilowatt hours of energy have gone up rapidly in the Western countries in the past 40 years, and developing countries such as India and China are expected to raise their averages significantly in the coming decades.
There are groups out there trying to do something about it. The 2,000 Watt Society, for example, is an organization backed in part by the Swiss Council of the Federal Institute of Technology. Its goal is to reduce energy consumption so that no country's citizens uses more than an average of 2,000 watts per year.
The goal can be achieved, according to a paper laying out the 2,000 Watt Society's plans, by achieving dramatically better energy efficiency rather than by, say, cutting back on the standard of living enjoyed in the developed world. They also envision improvements in the materials we use as well as steps such as "adopting a smarter way of life and rethinking current business practices," whatever that means. Clearly, much more has to be done in terms of reducing the developed world's dependence on fossil fuels if the 2,000-watt goal is to be achieved.
As an indication of just how difficult a mission it will be to reduce consumption to 2,000 watts for someone in the industrialized world, anyone who drives a car an average amount each year--even a hybrid--or who travels by plane probably won't be able to live a 2,000-watt lifestyle. The New Yorker article found one family in Switzerland that actually was living a 2,000 watt lifestyle: a dentist, his wife, and their two children live in a house in an energy-efficient development that is heated by a geothermal heat pump, they have photovoltaic panels on the roof that produce all their electricity, they own no car (they live close to public transportation), and they travel on vacation only by train.
Interestingly, in their paper outlining how 2,000 watts might be achieved, the 2,000 Watts Society does not envision our having to give up airplane travel to meet the goal. In fact, other than assuming that new technologies will marginally improve airplane efficiency, they don't foresee much improvement in those areas. Instead, they foresee significant improvements in alternative energies and reductions in fossil fuel dependence.
If you are interested in learning more on kilowatts as an expression of energy consumption, explore any of the following: