Energy here refers to sources of power: electricity, gas, oil, coal, and so on. The world's finite resources of most energy sources (except sun and wind) were highlighted in a famous report "The Limits to Growth" written by the Club of Rome in 1970. Their dire predictions have not come to pass, but prices of several sources of energy have risen faster than inflation. Not only are they a significant source of cost for many companies, but there is also the moral obligation of using such resources wisely.

Although energy management systems in factory, office and home have grown in sophistication there still remains the human, common sense element: shutting down the machine, switching off the light, fixing the drip, insulating the roof, taking a full load, efficient routing, and the like. (By the way, the JIT system of delivery does not waste energy when done correctly: use "milkrounds", picking up small quantities from several suppliers in the same area, or rationalise suppliers so as to enable mixed loads daily rather than single products weekly.)

Several companies that have "institutionalised" waste reduction, Toyota included, believe that a good foundation for waste awareness begins with everyday wastes such as electricity. You get into the habit.