Decreasing consuption - maintaining standards
Energy efficiency is a way of managing and restraining the growth in energy consumption. Something is more energy efficient if it delivers more services for the same energy input, or the same services for less energy input. For example, when a compact florescent light (CFL) bulb uses less energy (one-third to one-fifth) than an incandescent bulb to produce the same amount of light, the CFL is considered to be more energy efficient.
Energy efficiency is normally associated with buildings and houses. Terms like zero-energy or near zero energy houses, as well as passive houses are common. But energy efficiency can also be achieved on a larger societal scale through solutions such as smart grids or urban logistics.