Energy efficiency is the amount of electricity, gasoline or other energy source used to accomplish a particular task or activity. Improving energy efficiency can provide important benefits, including reducing the emission of greenhouse gasses and other harmful substances and lowering costs for households and for an economy as a whole.
There has been a long run trend by businesses towards increasing the efficiency of energy usage, as there has been with other resources. This has historically been a result of the insatiable quest to reduce costs as a means of increasing profits. But in recent years it has also been increasingly due to growing awareness of and concern about environmental issues and to consequent pressure from government agencies and the public.
The areas in which energy efficiency has increased and will continue to increase are numerous. With regard to transportation, which is one of the biggest consumers of energy, they include more efficient engines for automobiles, aircraft, ships and railway vehicles. But energy efficiency in transport can often also be increased by modal shifting, such as by diverting freight and passengers from road transport to railroads and relatively short air passenger transport to high-speed railways. Railways can be much more energy efficient than road transport mainly because of the much less rolling resistance of steel wheels on steel rails as compared to rubber tires on roads.
As another example, energy efficiency continues to increase in households as a result of the use of more energy-efficient doors and windows, upgraded heating and cooling systems, improved thermostats, enhanced insulation, the use of energy-efficient appliances, and the replacement of conventional light bulbs with LED lighting. Energy efficiency in agriculture is continuing to improve as a result of such measures as improved machinery, adaption of precision agriculture, increased use of renewable energy and increased energy efficiency of farm buildings.
Increasing energy efficiency for individual products and sectors is a main component of minimizing the total world consumption of energy and particularly of non-renewable energy resources. But also important for reducing total energy consumption are broad shifts in consumption and production patterns, such as reducing sprawl in combination with improving public transport and walkability in urban areas, encouraging the production of more durable and easily reparable products, and replacing some meat consumption with plant-based food.