Energy conservation is the effort made to reduce the consumption of energy by using less of an energy service. This can be achieved either by using energy more efficiently (using less energy for a constant service) or by reducing the amount of service used (for example, by driving less). Energy conservation is a part of the concept of Eco-sufficiency. Energy conservation reduces the need for energy services and can result in increased environmental quality, national security, personal financial security and higher savings. It is at the top of the sustainable energy hierarchy. It also lowers energy costs by preventing future resource depletion.
Energy can be conserved by reducing wastage and losses, improving efficiency through technological upgrades and improved operation and maintenance. On a global level energy use can also be reduced by the stabilization of population growth.
Energy can only be transformed from one form to other, such as heat energy to motive power in cars, or kinetic energy of water flow to electricity in hydroelectric power plants. However machines are required to transform energy from one form to other. The wear and friction of the components of these machine while running cause losses of very high amounts of energy and very high related costs. It is possible to minimize these losses by adopting green engineering practices to improve life cycle of the components.
Energy conservation day is celebrated on December 14 every year since 1991.
Some countries employ energy or carbon taxes to motivate energy users to reduce their consumption. Carbon taxes can motivate consumption to shift to energy sources with less emissions of carbon dioxide, such as solar power, wind power, hydroelectricity or nuclear power while avoiding cars with combustion engines, jet fuel, oil, fossil gas and coal. On the other hand, taxes on all energy consumption can reduce energy use across the board while reducing a broader array of environmental consequences arising from energy production. The state of California employs a tiered energy tax whereby every consumer receives a baseline energy allowance that carries a low tax. As usage increases above that baseline, the tax increases drastically. Such programs aim to protect poorer households while creating a larger tax burden for high energy consumers.
One of the primary ways to improve energy conservation in buildings is to perform an energy audit. An energy audit is an inspection and analysis of energy use and flows for energy conservation in a building, process or system with an eye toward reducing energy input without negatively affecting output. This is normally accomplished by trained professionals and can be part of some of the national programs discussed above. Recent development of smartphone apps enables homeowners to complete relatively sophisticated energy audits themselves.
Building technologies and smart meters can allow energy users, both commercial and residential, to visualize the impact their energy use can have in their workplace or homes. Advanced real-time energy metering can help people save energy by their actions.
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.
The key to designing a passive solar building is to best take advantage of the local climate. Elements to be considered include window placement and glazing type, thermal insulation, thermal mass, and shading. Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be retrofitted.
In the United States, suburban infrastructure evolved during an age of relatively easy access to fossil fuels, which has led to transportation-dependent systems of living. Zoning reforms that allow greater urban density as well as designs for walking and bicycling can greatly reduce energy consumed for transportation. The use of telecommuting by major corporations is a significant opportunity to conserve energy, as many Americans now work in service jobs that enable them to work from home instead of commuting to work each day.
Consumers are often poorly informed of the savings of energy efficient products. A prominent example of this is the energy savings that can be made by replacing an incandescent light bulb with a more modern alternative. When purchasing light bulbs, many consumers opt for cheap incandescent bulbs, failing to take into account their higher energy costs and lower lifespans when compared to modern compact fluorescent and LED bulbs. Although these energy-efficient alternatives have a higher upfront cost, their long lifespan and low energy use can save consumers a considerable amount of money. The price of LED bulbs has also been steadily decreasing in the past five years due to improvements in semiconductor technology. Many LED bulbs on the market qualify for utility rebates that further reduce the price of purchase to the consumer. Estimates by the U.S. Department of Energy state that widespread adoption of LED lighting over the next 20 years could result in about $265 billion worth of savings in United States energy costs.
The research one must put into conserving energy is often too time consuming and costly for the average consumer when there are cheaper products and technology available using today's fossil fuels. Some governments and NGOs are attempting to reduce this complexity with Eco-labels that make differences in energy efficiency easy to research while shopping.
To provide the kind of information and support people need to invest money, time and effort in energy conservation, it is important to understand and link to people's topical concerns. For instance, some retailers argue that bright lighting stimulates purchasing. However, health studies have demonstrated that headache, stress, blood pressure, fatigue and worker error all generally increase with the common over-illumination present in many workplace and retail settings. It has been shown that natural daylighting increases productivity levels of workers, while reducing energy consumption.
In warm climates where air conditioning is used, any household device that gives off heat will result in a larger load on the cooling system. Items such as stoves, dish washers, clothes dryers, hot water and incandescent lighting all add heat to the home. Low-power or insulated versions of these devices give off less heat for the air conditioning to remove. The air conditioning system can also improve in efficiency by using a heat sink that is cooler than the standard air heat exchanger, such as geothermal or water.
In cold climates, heating air and water is a major demand on household energy use. Significant energy reductions are possible by using different technologies. Heat pumps are a more efficient alternative to electrical resistance heaters for warming air or water. A variety of efficient clothes dryers are available, and the clothes lines requires no energy- only time. Natural-gas (or bio-gas) condensing boilers and hot-air furnaces increase efficiency over standard hot-flue models. Standard electric boilers can be made to run only at hours of the day when they are needed by means of a time switch. This decreases energy use vastly. In showers, a semi-closed-loop system could be used. New construction implementing heat exchangers can capture heat from waste water or exhaust air in bathrooms, laundry and kitchens.
In both warm and cold climate extremes, airtight thermal insulated construction is the largest factor determining the efficiency of a home. Insulation is added to minimize the flow of heat to or from the home, but can be labor-intensive to retrofit to an existing home.
Energy conservation by countries
Despite the vital role energy efficiency is expected to play in cost-effectively cutting energy demand, only a small part of its economic potential is exploited in Asia. Governments have implemented a range of subsidies such as cash grants, cheap credit, tax exemptions, and co-financing with public-sector funds to encourage a range of energy-efficiency initiatives across several sectors. Governments in the Asia-Pacific region have implemented a range of information provision and labelling programs for buildings, appliances, and the transportation and industrial sectors. Information programs can simply provide data, such as fuel-economy labels, or actively seek to encourage behavioural changes, such as Japan's Cool Biz campaign that encourages setting air conditioners at 28-degrees Celsius and allowing employees to dress casually in the summer.
At the end of 2006, the European Union (EU) pledged to cut its annual consumption of primary energy by 20% by 2020. The 'European Union Energy Efficiency Action Plan' is long-awaited. Directive 2012/27/EU is on energy efficiency.
As part of the EU's SAVE programme, aimed at promoting energy efficiency and encouraging energy-saving behavior, the Boiler Efficiency Directive specifies minimum levels of efficiency for boilers utilizing liquid or gaseous fuels.
In 2050, energy savings in Europe can reach 67% of the 2019 baseline scenario, amounting to a demand of 361 MToe in an 'energy efficiency first' societal trend scenario. A condition is that there be no rebound effect, for otherwise the savings are 32% only or energy use may even increase by 42% if techno-economic potentials are not realised. 
The Petroleum Conservation Research Association (PCRA) is an Indian governmental body created in 1978 that engages in promoting energy efficiency and conservation in every walk of life. In the recent past PCRA has done mass-media campaigns in television, radio, and print media. This is an impact-assessment survey by a third party revealed that due to these larger campaigns by PCRA, the public's overall awareness level has gone up leading to saving of fossil fuels worth crores of rupees, besides reducing pollution.
The Bureau of Energy Efficiency is an Indian government organisation created in 2001 that is responsible for promoting energy efficiency and conservation.
Protection and Conservation of Natural Resources is done by Community Natural Resources Management (CNRM).
The Energy Conservation Center promotes energy efficiency in every aspect of Japan. Public entities are implementing the efficient use of energy for industries and research. It includes projects such as the Top Runner Program. In this project, new appliances are regularly tested on efficiency, and the most efficient ones are made the standard.
In Lebanon and since 2002 The Lebanese Center for Energy Conservation (LCEC) has been promoting the development of efficient and rational uses of energy and the use of renewable energy at the consumer level. It was created as a project financed by the International Environment Facility (GEF) and the Ministry of Energy Water (MEW) under the management of the United Nations Development Programme (UNDP) and gradually established itself as an independent technical national center although it continues to be supported by the United Nations Development Programme (UNDP) as indicated in the Memorandum of Understanding (MoU) signed between MEW and UNDP on 18 June 2007.
Until recently, Nepal has been focusing on the exploitation of its huge water resources to produce hydro power. Demand side management and energy conservation was not in the focus of government action. In 2009, bilateral Development Cooperation between Nepal and the Federal Republic of Germany, has agreed upon the joint implementation of "Nepal Energy Efficiency Programme". The lead executing agencies for the implementation are the Water and Energy Commission Secretariat (WECS). The aim of the programme is the promotion of energy efficiency in policy making, in rural and urban households as well as in the industry. Due to the lack of a government organization that promotes energy efficiency in the country, the Federation of Nepalese Chambers of Commerce and Industry (FNCCI) has established the Energy Efficiency Centre under his roof to promote energy conservation in the private sector. The Energy Efficiency Centre is a non-profit initiative that is offering energy auditing services to the industries. The Centre is also supported by Nepal Energy Efficiency Programme of Deutsche Gesellschaft für Internationale Zusammenarbeit. A study conducted in 2012 found out that Nepalese industries could save 160,000 megawatt hours of electricity and 8,000 terajoule of thermal energy (like diesel, furnace oil and coal) every year. These savings are equivalent to annual energy cost cut of up to 6.4 Billion Nepalese Rupees. As a result of Nepal Economic Forum 2014, an economic reform agenda in the priority sectors was declared focusing on energy conservation among others. In the energy reform agenda the government of Nepal gave the commitment to introduce incentive packages in the budget of the fiscal year 2015/16 for industries that practices energy efficiency or use efficient technologies (incl. cogeneration).
In New Zealand the Energy Efficiency and Conservation Authority is the Government Agency responsible for promoting energy efficiency and conservation. The Energy Management Association of New Zealand is a membership based organization representing the New Zealand energy services sector, providing training and accreditation services with the aim of ensuring energy management services are credible and dependable.
In Nigeria, the Lagos State Government is encouraging Lagosians to imbibe an energy conservation culture. In 2013, the Lagos State Electricity Board (LSEB) ran an initiative tagged "Conserve Energy, Save Money" under the Ministry of Energy and Mineral Resources. The initiative is designed to sensitize Lagosians around the theme of energy conservation by influencing their behavior through do-it-yourself tips. In September 2013, Governor Babatunde Raji Fashola of Lagos State and the campaign ambassador, rapper Jude 'MI' Abaga participated in the Governor's conference video call on the topic of energy conservation.
In addition to this, during the month of October (the official energy conservation month in the state), LSEB hosted experience centers in malls around Lagos State where members of the public were encouraged to calculate their household energy consumption and discover ways to save money using a consumer-focused energy app. To get Lagosians started on energy conservation, solar lamps and energy-saving bulbs were also handed out.
In Kaduna State, the Kaduna Power Supply Company (KAPSCO) ran a program to replace all light bulbs in Public Offices; fitting energy-saving bulbs in place of incandescent bulbs. KAPSCO is also embarking on an initiative to retrofit all conventional streetlights in the Kaduna Metropolis to LEDs which consume much less energy.
Sri Lanka currently consumes fossil fuels, hydro power, wind power, solar power and dendro power for their day to day power generation. The Sri Lanka Sustainable Energy Authority is playing a major role regarding energy management and energy conservation. Today, most of the industries are requested to reduce their energy consumption by using renewable energy sources and optimizing their energy usage.
The United States is currently the second largest single consumer of energy, following China. The U.S. Department of Energy categorizes national energy use in four broad sectors: transportation, residential, commercial, and industrial.
Energy usage in transportation and residential sectors, about half of U.S. energy consumption, is largely controlled by individual consumers. Commercial and industrial energy expenditures are determined by businesses entities and other facility managers. National energy policy has a significant effect on energy usage across all four sectors.
Another aspect of energy conversation is using Leadership in Energy and Environmental Design. (LEED) This program is not mandatory, it is voluntary. This program has many categories, Energy and Atmosphere Prerequisite, applies to energy conservation. This section focuses on energy performance, renewable energy, energy performance, and many more. This program is designed to promote energy efficiency and be a green building, which is part of conservation. As mention above “energy conservation are efforts made to reduce the consumption of energy.”
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