GC: n
CT: Energy efficiency is “using less energy to provide the same service”.
There are other definitions, but this is a good operational one.
The best way to understand this idea is through examples:
- When you replace a single pane window in your house with an energy-efficient one, the new window prevents heat from escaping in the winter, so you save energy by using your furnace or electric heater less while still staying comfortable. In the summer, efficient windows keep the heat out, so the air conditioner does not run as often and you save electricity.
- When you replace an appliance, such as a refrigerator or clothes washer, or office equipment, such as a computer or printer, with a more energy-efficient model, the new equipment provides the same service, but uses less energy. This saves you money on your energy bill, and reduces the amount of greenhouse gases going into the atmosphere.
S: http://eetd.lbl.gov/ee/ee-1.html (last access: 13 February 2015)
N: 1. energy (n): 1590s, “force of expression,” from Middle French énergie (16c.), from Late Latin energia, from Greek energeia “activity, action, operation,” from energos “active, working,” from en “at” + ergon “work, that which is wrought; business; action”.
Used by Aristotle with a sense of “actuality, reality, existence” (opposed to “potential”) but this was misunderstood in Late Latin and afterward as “force of expression,” as the power which calls up realistic mental pictures. Broader meaning of “power” in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.
efficiency (n): 1590s, “power to accomplish something,” from Latin efficientia “efficient power; efficiency; influence” (from efficientem; see efficient) + -cy. In mechanics, “ratio of useful work done to energy expended,” from 1858. Attested from 1952 as short for efficiency apartment (itself from 1920).
2. The effectiveness with which delivered energy is converted into useful energy for heating, lighting, processes, etc.
3. Energy efficiency is not energy conservation.
Energy conservation is reducing or going without a service to save energy.
For example: Turning off a light is energy conservation. Replacing an incandescent lamp with a compact fluorescent lamp (which uses much less energy to produce the same amount of light) is energy efficiency.
Both efficiency and conservation can reduce greenhouse gas emissions.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=energy+efficiency&searchmode=none (last access: 13 February 2015). 2. TERMIUM PLUS (last access: 13 February 2015). 3. http://eetd.lbl.gov/ee/ee-1.html (last access: 13 February 2015).
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