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In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or, when multiplied by 100, is given as a percentage. The energy efficienctyrtytytyy of a process, denoted by eta, is defined as Efficient energy use, sometimes simply called energy efficiency, is using less energy to provide the same level of energy service. ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... Engineering is the discipline of acquiring and applying knowledge of design, analysis, and/or construction of works for practical purposes. ... Mechanical Engineering is an engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems. ... Electrical Engineers design power systems… … and complex electronic circuits. ... In the physical sciences, a dimensionless number (or more precisely, a number with the dimensions of 1) is a quantity which describes a certain physical system and which is a pure number without any physical units; it does not change if one alters ones system of units of measurement... For other senses of this word, see zero or 0. ... This article is about the number one. ... Look up Η, η in Wiktionary, the free dictionary. ...

where output is the amount of mechanical work (in watts) or energy released by the process (in joules), and input is the quantity of work or energy used as input to run the process. In physics, mechanical work is the amount of energy transferred by a force. ... For other uses, see Watt (disambiguation). ... The joule (IPA: or ) (symbol: J) is the SI unit of energy. ...

Due to the principle of conservation of energy, energy efficiency within a closed system can never exceed 100%. Look up conservation of energy in Wiktionary, the free dictionary. ...

Energy efficiency and global warming

Main article: Global warming

Making homes, vehicles, and businesses more energy efficient is seen as a largely untapped solution to addressing global warming and energy security. Many of these ideas have been discussed for years, since the 1973 oil crisis brought energy issues to the forefront. In the late 1970s, physicist Amory Lovins popularized the notion of a "soft path" on energy, with a strong focus on energy efficiency. Among other things, Lovins popularized the notion of negawatts -- the idea of meeting energy needs by increasing efficiency instead of increasing energy production. Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Energy security, or security of supply, is a key component of energy policy in many countries. ... The 1973 oil crisis began in earnest on October 17, 1973, when the members of Organization of Arab Petroleum Exporting Countries (OAPEC, consisting of the Arab members of OPEC plus Egypt and Syria) announced, as a result of the ongoing Yom Kippur War, that they would no longer ship petroleum... Amory Lovins Amory Bloch Lovins (born November 13, 1947 in Washington, DC) was trained in physics and has worked professionally as an environmentalist. ... A negawatt is an hypothetical tradeable unit of energy saved. ...

Energy efficiency has proved to be a cost-effective strategy for building economies without necessarily growing energy consumption, as environmental business strategist Joel Makower has noted. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code and appliance standards with strict efficiency requirements. During the following years, California's energy consumption has remained approximately flat on a per capita basis while national U.S. consumption doubled. As part of its strategy, California implemented a three-step plan for new energy resources that puts energy efficiency first, renewable electricity supplies second, and new fossil-fired power plants last. Energy consumption is a measure of the rate of energy use such as fuels or electricity. ... Joel Makower (b. ... This article is about the U.S. state. ...

Still, efficiency often has taken a secondary position to new power generation as a solution to global warming in creating national energy policy. Some companies also have been reluctant to engage in efficiency measures, despite the often favorable returns on investments that can result. Lovins' Rocky Mountain Institute points out that in industrial settings, "there are abundant opportunities to save 70% to 90% of the energy and cost for lighting, fan, and pump systems; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances." In general, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less than the electricity itself. Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Energy policy is the manner a given entity (often governmental) has decided to address issues of energy development including energy production, distribution and consumption. ... According to its web site, Rocky Mountain Institute is an entrepreneurial nonprofit organization that fosters the efficient and restorative use of natural, human and other capital to make the world more secure, just, prosperous, and life-sustaining. ...

Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute, asserted that "there are sufficient economically viable opportunities for energy-productivity improvements that could keep global energy-demand growth at less than 1 percent per annum" -- less than half of the 2.2 percent average growth anticipated through 2020 in a business-as-usual scenario. Energy productivity -- which measures the output and quality of goods and services per unit of energy input -- can come from either reducing the amount of energy required to produce something, or from increasing the quantity or quality of goods and services from the same amount of energy.

The Vienna Climate Change Talks 2007 Report, under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows "that energy efficiency can achieve real emission reductions at low cost" ^[1] The Kyoto Protocol, the worlds first treaty to attempt to address global warming by limiting greenhouse gas emissions, is due to expire at the end of 2012. ... UNFCCC logo. ...

See also

Wikimedia Commons has media related to:

Energy efficiency

• 40mpg.org
• Energy conversion eryrtyyttyfficiency.
• EPACT92
• EROEI
• Exergy efficiency.
• Figure of merit.
• Fuel efficiency.
• Hybrid and plug-in hybrid vehicles.
• International Electrotechnical Commission.
• National Energy Action (WWE) (in the UK).
• National Electrical Manufacturers Association (UFC).
• Sensitivity (electronics).
• Thermal efficiency.

Image File history File links Commons-logo. ... MPG or mpg is a three-letter acronym with several meanings, including: Max-Planck-Gesellschaft - The Max Planck society for the advancement of science is an important German non-profit research organisation. ... The Energy Policy Act (109th Congress H.R.776. ... In physics, energy economics and ecological energetics, EROEI (Energy Returned on Energy Invested), ERoEI, or EROI (Energy Return On Investment), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource. ... Exergy efficiency is also called second-law efficiency because it computes the efficiency of a process taking the second law of thermodynamics into account. ... A Figure of merit is a quantity used to characterize the performance of a device relative to other devices of the same type. ... Fuel efficiency, in its basic sense, is the same as thermal efficiency, meaning the efficiency of a process that converts energy contained in a carrier fuel into energy or work. ... For other types of Hybrid Transportation, see Hybrid (disambiguation)#Transportation. ... Hybrids Plus plug-in hybrid Toyota Prius conversion with PHEV-30 (30 mile or 48 km all-electric range) battery packs A plug-in hybrid electric vehicle (PHEV) is a hybrid vehicle with batteries that can be recharged by connecting a plug to an electric power source. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... National Energy Action (NEA) is a UK charity that combats the heating and insulation problems of low-income households by encouraging the use of energy efficiency services. ... This article is about the standards association NEMA. For other uses, see Nema. ... The sensitivity of an electronic device, a communications system receiver, or detection device, PIN diode, is the minimum magnitude of input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria. ... The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ...

References

External links

• Energy Efficiency Global Forum and Exposition.
• Conversion of sensitivity in dB per Watt and meter to energy efficiency in percent for passive loudspeakers
• Find out how energy efficient your home is
• Energy Efficiency Program for Certain Commercial and Industrial Equipment: Test Procedures, Labeling, and Certification Requirements for Electric Motors; Final Rule (Office of Energy Efficiency and Renewable Energy).
• Reegle: Information Gateway For Renewable Energy And Energy Efficiency
• Center for Energy and innovative Technologies
• American Council for an Energy-Efficient Economy