The term efficiency is taken to mean the precise definition in physics and chemistry and is discussed here.
Energy efficiency refers to attempting to get a desired energy service using less primary energy (either fuels or flows). This goal is usually based on having less of an environmental impact and often attempts to be more sustainable, although sometimes people are seeking energy efficiency to save money.
There are numerous ways to improve energy efficiency within the home. Some changes are smaller, something as simple as changing the type of light bulb used can boost energy efficiency. Other upgrades to a home, for example choosing a higher-quality insulation - improve energy efficiency but are most labour intensive and expensive. Overall, there are numerous ways to improve the energy efficiency of the home by slightly altering the building design of the home.
Figure 1. Ensuring the proper location and setting of a thermostat can boost energy efficiency in the home.
Figure 2. Changing to CFL lightbulbs, shown above, increases energy efficiency.
As mentioned above, there are several ways to increase the energy efficiency of a process by making a simple change. Some processes include energy services that don't require much energy in the first place, but many of them are quite energy intensive. Changes that can be made to improve energy efficiency vary for what's being done with the energy.
The energy use in new buildings can be dramatically improved using better construction practices like building LEED certified buildings, and net-zero buildings. Improvements can also be made to buildings that currently exist as well. Some improvements include:
Transportation can also have significant improvements to energy efficiency. This usually means less vehicle use:
All of the products that are used by people, even food have a fair amount of embedded energy, this can be reduced by:
Many programs exist to try to get consumers to use less energy, often electricity specifically. These include Energy Star and other programs.
See also negawatts for the specific term that quantifies how much electricity is not used.