Modern life depends principally on the burning of fossil fuels. At work and at home we depend on piped natural gas or electricity for cooking, water and space heating, and the operation of mechanical and electrical equipment.

Of increasing concern is the life expectancy of our reserves of fossil fuels. No matter how efficiently we burn fossil fuels, we produce carbon dioxide, which is the principal greenhouse gas. The United Kingdom's production of natural gas from the North Sea peaked in 1999 and was 23% below this peak by 2005. This is because supplies are dwindling, though not through any slackening of demand. We now import natural gas by pipeline and by ship from other countries. All of this stresses the need for business to improve their resource efficiency.