Energy efficiency has proven to be a cost-effective strategy for building economies without necessarily increasing energy consumption. For example, the state of California began implementing energy efficiency measures in the mid-1970s, including building codes and appliance standards with strict efficiency requirements. Over the years since, California's energy consumption has remained roughly flat on a per capita basis, while U.S. national consumption doubled. As part of its strategy, California implemented a "charging order" for new energy resources that puts energy efficiency first, renewable electricity supply second, and new fossil fuel power plants. States such as Connecticut and New York have created quasi-public green banks to help owners of residential and commercial buildings finance improvements. energy efficiency that reduce emissions and reduce energy costs for consumers.[8]​.

Lovin's Rocky Mountain Institute notes that, in industrial settings, "abundant opportunities exist to save 70% to 90% of the energy and cost of lighting systems, fans, and pumps; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances. Overall, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less. As with electricity itself, the same applies to home settings. The US Department of Energy has stated that there is potential for energy savings in the magnitude of 90 billion kWh by increasing home energy efficiency.[9]​.

Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute stated that "there are enough economically viable opportunities to improve energy productivity that could keep global energy demand growth at less than 1 percent annually," less than half the average of 2.2 percent. Expected growth through 2020 in a business-as-usual scenario.[10]​ Energy productivity, which measures the production and quality of goods and services per unit of energy input, can come from reducing the amount of energy required to produce something or from increasing the quantity or quality of goods and services for the same amount of energy. .

The 2007 Vienna Climate Change Report, sponsored by the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows that "energy efficiency can achieve true emissions reductions at low cost."[11]​.

International standards ISO 17743 and ISO 17742 provide a documented methodology for calculating and reporting energy savings and energy efficiency for countries and cities.[12]​[13]​.

From an energy consumer's point of view, the primary motivation for energy efficiency is often simply to save money by reducing the cost of purchasing energy. Furthermore, from an energy policy point of view, there has been a long trend in a broader recognition of energy efficiency as the "first fuel", that is, the ability to replace or avoid the consumption of real fuels. In fact, the International Energy Agency has calculated that the implementation of energy efficiency measures in the years 1974-2010 has prevented more energy consumption in its Member States than the consumption of any particular fuel, including oil, coal and natural gas.[14]​.

In addition, it has long been recognized that energy efficiency brings additional benefits to reducing energy consumption.[15] Some estimates of the value of these other benefits, often called multiple benefits, complementary benefits, ancillary benefits or non-energy benefits, have put their total value even higher than that of the direct energy benefits.[16] These multiple benefits of energy efficiency include things such as reducing the impact of climate change, reducing air pollution and improving health, improving living conditions. interiors, improving energy security and reducing price risk for energy consumers. Methods have been developed to calculate the monetary value of these multiple benefits, including, for example, the experimental method of choice for improvements that have a subjective component (such as aesthetics or comfort)[14]​ and the Tuominen-Seppänen method for price risk reduction.[17]​ When included in the analysis, the economic benefit of investments in energy efficiency can be shown to be significantly greater than simply the value of the energy saved.[14]​.

Contenido

La calefacción puede ser objeto de ahorro de energía principalmente con hábitos de consumo tales como un uso racional del mismo, el consumo total de una vivienda suele ser del 46 % del total del consumo[18]​ (pudiendo alcanzar el 60 % si se incluye el agua caliente). El ahorro de energía puede producirse bien por la correcta elección de una caldera "Caldera (calefacción)") eficiente, o por el correcto aislamiento térmico de las habitaciones.

Respecto del agua caliente puede emplearse también como ayuda la energía solar térmica, mediante uso de sistemas de almacenamiento de energía que retengan el calor para que el agua caliente esté disponible la mayor parte de tiempo posible. Así mismo, se puede ahorrar energía dotando a los grifos y lavado de perlizadores") y a las duchas con reductores volumétricos de caudal o alcachofas de mano eco-eficientes. De esta forma se puede reducir el consumo de la energía empleada en calentar agua en más del 40%. Si al inodoro se le instala un mecanismo de doble pulsador, el ahorro de agua puede ser superior al 70%, pero en este caso no se ahorra energía, ya que, el inodoro sólo usa agua fría.

Se debe tener presente que una temperatura para un hogar está entre los 19 y los 21 °C por el día, y 15 a 17 °C por la noche, cada grado aumenta el consumo en un 7%.[19]​ Con estas consideraciones se aconseja:.

• - Adecuar el vestido en el domicilio con las condiciones de temperatura, se pueden emplear edredones, mantas y prendas similares.

• - No tapar u obstruir los radiadores ya que su función es la de emitir calor, y esta se ve entorpecida con la colocación de muebles.

• - Vigilar el aislamiento de las habitaciones, impidiendo fugas de calor o entradas de aire frío procedente de ventanas abiertas.

El empleo del agua caliente se realiza en la vivienda bajo ciertas ocasiones muy específicas como puede ser la ducha, o el baño, limpiando los platos y la cubertería, etc. En todos ellos se aconseja emplear agua caliente sólo cuando se necesite, al lavar no siempre se necesita.

Appliances

Modern appliances, such as freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use much less energy than older appliances. Installing a clothesline will significantly reduce energy consumption as the dryer will be used less. Current energy-efficient refrigerators, for example, use 40 percent less energy than conventional models in 2001. After this, if all households in Europe replaced their appliances older than ten years with new ones, 20 billion kWh of electricity would be saved annually, which would reduce CO emissions by almost 18 billion kg.[20]​ In the United States, the corresponding figures would be 17 billion kWh of electricity and 27 000,000,000 pounds (12,246,984,000 kg) CO.[21]​ According to a 2009 study by McKinsey & Company, replacing old appliances is one of the most efficient global measures to reduce greenhouse gas emissions.[22]​ Modern energy management systems also reduce the energy use of idle devices by turning them off or putting them in a low-power mode. after a certain time. Many countries identify energy efficient appliances that use energy input labels.[23]​.

The impact of energy efficiency on peak demand depends on when the appliance is used. For example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an energy efficient air conditioner will have a greater impact on peak demand than off-peak demand. An energy-efficient dishwasher, on the other hand, uses more energy at night when people wash their dishes. This device may have little or no impact on peak demand.

Buildings are an important area for energy efficiency improvements worldwide due to their role as a major consumer of energy. However, the issue of energy use in buildings is not simple, since the indoor conditions that can be achieved with energy use vary greatly. The measures that make buildings comfortable – lighting, heating, cooling and ventilation – consume energy. Typically, the level of energy efficiency in a building is measured by dividing the energy consumed with the floor area of ​​the building which is known as specific energy consumption (SEC) or energy use intensity (EUI):[26]​.

However, the problem is more complex since construction materials have incorporated energy into them. On the other hand, energy can be recovered from materials when the building is dismantled by reusing the materials or burning them for energy. Additionally, when the building is used, interior conditions may vary, resulting in higher and lower quality interior environments. Finally, overall efficiency is affected by the use of the building: is the building occupied most of the time and are the spaces used efficiently, or is the building largely empty? It has even been suggested that for a more complete accounting of energy efficiency, the SEC should be amended to include these factors:[27]​.

Therefore, a balanced approach to energy efficiency in buildings should be more comprehensive than simply trying to minimize the energy consumed. Issues such as the quality of the indoor environment and the efficiency of space use must be taken into account. Measures used to improve energy efficiency can therefore take many different forms. They often include passive measures that inherently reduce the need to use energy, such as better insulation. Many serve several functions that improve indoor conditions and reduce energy use, such as increasing the use of natural light.

The location and environment of a building play a key role in regulating its temperature and lighting. For example, trees, landscaping, and hills can provide shade and block wind. In colder climates, designing northern hemisphere buildings with south-facing windows and southern hemisphere buildings with north-facing windows increases the amount of sun (ultimately thermal energy) entering the building, minimizing energy use, by maximizing passive solar heating. Compact building design, including energy-efficient windows, well-sealed doors, and additional thermal insulation of walls, basement slabs, and foundation can reduce heat loss by 25 to 50 percent.[23][28]​.

Dark ceilings can be up to 70°F (39°C) warmer than more reflective white surfaces. They transmit some of this extra heat into the building. US studies have shown that light-colored roofs use 40 percent less energy for cooling than buildings with darker roofs. White roof systems save more energy in sunnier climates. Advanced electronic heating and cooling systems can moderate energy consumption and improve the comfort of people in the building.[23]​.

Proper placement of windows and skylights, as well as the use of light-reflecting architectural features in a building can reduce the need for artificial lighting. One study has shown that increasing the use of natural and task lighting increases productivity in schools and offices.[23] Compact fluorescent lamps use two-thirds less energy and can last 6 to 10 times longer than incandescent bulbs. Newer fluorescent lights produce natural light, and in most applications are cost effective, despite their higher initial cost, with payback periods as low as a few months. LED lamps use only about 10% of the energy required by an incandescent lamp.

Effective energy-efficient building design can include using low-cost passive infrared (PIR) to turn off lighting when areas are unoccupied, such as toilets, hallways, or even office areas after hours. Additionally, lux levels can be monitored using daylight sensors linked to the building's lighting scheme to turn lighting on/off or dim to predefined levels to take into account natural light and thus reduce consumption. Building management systems (BMS) link all of this into a centralized computer to control the lighting and energy requirements of the entire building.[29]​.

In an analysis that integrates a residential bottom-up simulation with an economic multi-sector model, it has been shown that variable heat gains caused by insulation and air conditioning efficiency can have non-uniform load shifting effects on electrical load. The study also highlighted the impact of greater household efficiency on the electricity generation capacity choices made by the electricity sector.[30]​.

The choice of space heating or cooling technology to use in buildings can have a significant impact on energy use and efficiency. For example, replacing an old natural gas furnace with 50% efficiency with a new one with 95% efficiency will dramatically reduce energy consumption, carbon emissions, and natural gas bills in the winter. Ground source heat pumps can be even more energy efficient and cost effective. These systems use pumps and compressors to move refrigerant fluid around a thermodynamic cycle in order to "pump" heat against its natural flow from hot to cold, in order to transfer heat to a building from the large thermal reservoir contained within the nearby ground. The end result is that heat pumps typically use four times less electrical energy to supply an equivalent amount of heat than a direct electric heater. Another advantage of a ground source heat pump is that it can be reversed in summer and operate to cool the air by transferring heat from the building to the ground. The disadvantage of ground source heat pumps is their high initial capital cost, but this is usually paid back within five to ten years as a result of lower energy use.

Smart meters are slowly being adopted by the commercial sector for staff highlighting and for internal monitoring purposes of building energy usage in a dynamic presentable format. The use of power quality analyzers can be introduced into an existing building to evaluate usage, harmonic distortion, spikes, surges, interruptions, among others, to ultimately make the building more energy efficient. Often such meters communicate using wireless sensor networks.

Green Building XML") (gbXML) is an emerging schema, a subset of Building Information Modeling efforts, focused on the design and operation of green buildings. gbXML is used as input in several energy simulation engines. But with the development of modern computer technology, there are a large number of building performance simulation tools available on the market. When choosing which simulation tool to use in a project, the user must consider the accuracy and reliability of the tool, taking into account the building information they have on hand, which will serve as input for the tool. Yezioro, Dong and Leite[31]​ developed an artificial intelligence approach to evaluate the building performance simulation results and found that the most detailed simulation tools have the best simulation performance in terms of heating and cooling electricity consumption within 3% of the mean absolute error.

Leadership in Energy and Environmental Design (LEED) is a rating system organized by the US Green Building Council (USGBC) to promote environmental responsibility in building design. They currently offer four levels of certification for existing buildings (LEED-EBOM) and new construction (LEED-NC) based on a building's compliance with the following criteria: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Design Innovation. In 2013, USGBC developed the LEED Dynamic Plaque, a tool to track building performance against LEED metrics and a potential path to recertification. collaborated with Honeywell to collect data on energy and water usage, as well as indoor air quality from a BAS to automatically update the board, providing a near real-time view of performance. The USGBC office in Washington, D.C., is one of the first buildings to feature the live-updating LEED dynamic board.[33]​.

A deep energy retrofit is a whole-building analysis and construction process that is used to achieve much greater energy savings than conventional energy retrofits. Deep energy retrofits can be applied to residential and non-residential ("commercial") buildings. A deep energy retrofit typically results in energy savings of 30 percent or more, perhaps spread over several years, and can significantly improve the value of the building.[34] The Empire State Building has undergone a deep energy retrofit process that is completed in 2013. The project team, comprised of representatives from Johnson Controls, Rocky Mountain Institute, Clinton Climate Initiative, and Jones Lang LaSalle, will have achieved a 38%, $4.4 million annual energy use reduction. For example, the 6,500 windows were remanufactured on-site into "super windows" that block heat but let in light. Air conditioning operating costs on hot days were reduced and this saved $17 million off the project's capital cost immediately, partly funding other repairs.[36]​ Receiving a Leadership in Energy and Environmental Design (LEED) gold rating in September 2011, the Empire State Building is the tallest LEED-certified building in the United States.[24]​ The Indianapolis City-County Building recently underwent a renovation process. deep energy retrofit, which has achieved a 46% annual energy reduction and $750,000 annual energy savings.

Energy retrofits, including deep retrofits, and other types performed in residential, commercial, or industrial locations are typically supported through various forms of financing or incentives. Incentives include pre-packaged refunds where the buyer/user may not even know that the item being used has been refunded or "purchased." “Upstream” or “midstream” purchases are common for efficient lighting products. Other discounts are more explicit and transparent to the end user through the use of formal applications. In addition to rebates, which may be offered through government or utility programs, governments sometimes offer tax incentives for energy efficiency projects. Some entities offer rebate and payment facilitation and guidance services that enable energy end-use customers to take advantage of incentive and incentive programs.

To evaluate the economic soundness of energy efficiency investments in buildings, cost-effectiveness analysis or CEA can be used. A CEA calculation will produce the value of the energy saved, sometimes called negawatts, in $/kWh. The energy in such a calculation is virtual in the sense that it was never consumed but was saved due to an investment in energy efficiency. CEA therefore allows the price of negawatts to be compared to the price of energy, such as electricity from the grid or the cheapest renewable alternative. The benefit of the CEA approach in energy systems is that it avoids the need to guess at future energy prices for calculation purposes, thus eliminating the main source of uncertainty in the evaluation of energy efficiency investments.[37]​.

Europe

In Europe, energy efficiency targets have been set for 2020 and 2030.

The first EU-wide target was set in 1998. Member States agreed to improve energy efficiency by 1 percent per year for twelve years. In addition, legislation on products, industry, transport and buildings has contributed to an overall energy efficiency framework. Greater effort is needed to address heating and cooling: more heat is wasted during electricity production in Europe than is required to heat all buildings on the continent.[38]​ Overall, EU energy efficiency legislation is estimated to deliver savings equivalent to up to 326 million tonnes of oil per year by 2020.[39]​.

The EU set an energy savings target of 20% by 2020 compared to 1990 levels, but Member States decide individually how energy savings will be achieved. At an EU summit in October 2014, EU countries agreed on a new energy efficiency target of 27% or more by 2030. One mechanism used to achieve the 27% target is "Supplier Obligations and Blank Certificates".[40] The ongoing debate around the 2016 Clean Energy Package also places emphasis on energy efficiency, but the target will likely remain around 30% more efficient compared with 1990 levels.[39] Some have argued that this will not be enough for the EU to meet the Paris Agreement goals of reducing greenhouse gas emissions by 40% compared to 1990 levels.

Australia

The Australian national government is actively leading the country in efforts to increase its energy efficiency, primarily through the government's Department of Industry and Science. In July 2009, the Council of Australian Governments, representing Australia's states and territories, agreed on a National Strategy on Energy Efficiency (NSEE).[41]​.

This is a ten-year plan that accelerates the implementation of a nationwide adoption of energy efficiency practices and a preparation for the country's transformation to a low-carbon future. There are several different areas of energy use addressed within the NSEE. However, the chapter dedicated to the approach to energy efficiency to be adopted at national level highlights four points in achieving the declared levels of energy efficiency. Are:.

• - To help households and businesses transition to a low carbon future.

• - Expedite the adoption of efficient energy.

• - Make buildings more energy efficient.

• - For governments to work in partnership and lead the way towards energy efficiency.

The main agreement governing this strategy is the National Partnership Agreement on Energy Efficiency.[42]​.

This document also explains the role of the community and individual states and territories in the NSEE, as well as the creation of benchmarks and measurement devices that will transparently show the nation's progress against the stated objectives, and addresses the need for funding the strategy to enable it to move forward.

Canada

In August 2017, the Government of Canada launched Build Smart – Canada's Buildings Strategy, as a key driver of the Pan-Canadian Framework on Clean Growth and Climate Change, Canada's national climate strategy.

The Build Smart strategy seeks to dramatically increase the energy efficiency performance of new and existing Canadian buildings, and sets five goals to that end:.

• - Federal, provincial and territorial governments will work to develop and adopt increasingly stringent model building codes, beginning in 2020, with the goal of provinces and territories adopting a "net zero energy" model building code by 2030.

• - Federal, provincial and territorial governments will work to develop a model code for existing buildings by 2022, with the goal of provinces and territories adopting the code.

• - Federal, provincial and territorial governments will work together with the goal of requiring labeling of construction energy use starting in 2019.

• - The federal government will set new standards for heating equipment and other key technologies at the highest level of efficiency that is economically and technically achievable.

• - Provincial and territorial governments will work to maintain and expand efforts to modernize existing buildings by supporting energy efficiency improvements and accelerating the adoption of high-efficiency equipment while adapting their programs to regional circumstances.

The strategy details a range of activities that the Government of Canada will undertake, and the investments it will make, to support the objectives. As of early 2018, only one of Canada's 10 provinces and three territories, British Columbia, has developed policy in support of the federal government's goal of achieving net-zero energy ambitions: the BC Energy Steps Code.

Local governments in British Columbia can use BC Energy's Code Steps, if they wish, to incentivize or require a level of energy efficiency in new construction that goes beyond the base building code requirements. The regulation and standard are designed as a technical roadmap to help the province achieve its goal that all new buildings will achieve a net-zero energy performance level by 2032.

Germany

Energy efficiency is central to energy policy in Germany.[43]​ At the end of 2015, the national policy includes the following efficiency and consumption targets (with actual values ​​for 2014):[44]​.

Recent progress towards greater efficiency has been steady, apart from the financial crisis of 2007–08.[45]​ However, some believe that energy efficiency is still not recognized in terms of its contribution to Germany's energy transformation (or Energiewende).[46]​.

Efforts to reduce final energy consumption in the transport sector have not been successful, with growth of 1.7% between 2005-2014. This growth is due to both road passenger transport and road freight transport. Both sectors increased the total distance traveled to record the highest figures in Germany. Rebound effects played an important role, both between improved vehicle efficiency and distance traveled, and between improved vehicle efficiency and an increase in vehicle weight and engine power.[47]​.

On December 3, 2014, the German federal government launched its National Action Plan on Energy Efficiency (NAPE).[48]​[49]​ The areas covered are energy efficiency of buildings, energy conservation for businesses, consumer energy efficiency and energy efficiency of transport. The policy contains immediate and future measures. NAPE's short-term core measures include the introduction of competitive tendering for energy efficiency, raising funds for building renovation, introducing tax incentives for efficiency measures in the construction sector and establishing energy efficiency networks together with business and industry. German industry is expected to make a considerable contribution.

On August 12, 2016, the German government published a green paper on energy efficiency for public consultation (in German).[50]​[51]​ It describes possible challenges and actions needed to reduce energy consumption in Germany in the coming decades. At the launch of the document, Economy and Energy Minister Sigmar Gabriel said that "we do not need to produce, store, transmit and pay for the energy we save."[50]​ The Green Paper prioritizes efficient energy use as the "first" response and also outlines opportunities for sector coupling, including the use of renewable energy for heating and transport.[50]​ Other proposals include a flexible energy tax that increases as gasoline prices fall, incentivizing fuel conservation despite low oil prices.[52]​.

Poland

In May 2016, Poland adopted a new Energy Efficiency Law, which came into force on October 1, 2016.[53]​.

USA

A 2011 Energy Modeling Forum study covering the United States examines how energy efficiency opportunities will shape future fuel and electricity demand in the coming decades. The U.S. economy is now ready to reduce its energy and carbon intensity, but explicit policies will be needed to meet climate goals. These policies include: a carbon tax, mandatory standards for more efficient appliances, buildings and vehicles, and subsidies or reductions in the initial costs of new, more energy-efficient equipment.[54]​.

Argentina

In 2016, the Argentine Institute for Standardization and Certification approved the IRAM Standard 11900 "Heating energy efficiency label for buildings". The aforementioned standard establishes a simplified methodology for calculating the level of energy efficiency of the envelope of buildings that can be heated. The results are displayed on a label, similar to that used to rate the energy efficiency of domestic appliances (refrigerators, washing machines, lamps, etc.). The thermal efficiency of the envelope is directly related to the thermal transmittance of the materials that form the building envelope. The standard establishes 8 levels of thermal efficiency of the envelope, from "A- green" with the most optimal efficiency to "H- brown" the least efficient. The class is determined by calculating the weighted average variation in temperature between the interior surface of each component of the envelope and the interior design temperature (20 °C).

Venezuela

64% of the electricity in the country is generated by waterfalls. There are 96 reservoirs in Venezuela, which store about 157 km of water. The Caroní River basin is the main electricity generator in the country, currently producing 24,229 Mega Watts (MW) of electrical potential, which represents 75% of the country's current total potential. Its extension is 92,170 km, towards the right bank of the Orinoco River (Guyana Region). This potential is exploited through the Guri, Caruachi and Macagua dams and soon the Tocoma dam (in the final stage of feasibility studies and preparation of the land for its construction). From 1963 to today, the electrical development of the lower Caroní has ​​allowed the country to save the consumption of 2,173 million barrels of oil equivalent. Tocoma would add about 2,250 MW of additional electrical power to the national grid from renewable energy sources, which if generated through thermoelectric plants, would represent a daily consumption of approximately 68,000 barrels of oil per day.

Spain

The Energy Efficiency Directive in buildings has been transposed in Spain through the Comprehensive Housing and Land Plan").[55]​[56]​.

According to this regulation, since June 1, 2013, it is mandatory that all properties that are sold or rented for a period of more than four months have an energy label obtained through a technical study or energy certification.

The energy label of the buildings will show a letter rating that will vary from A to G. The assessment will be based on the CO emitted by the energy consumption of the heating, cooling, domestic hot water and lighting installations of the building under certain conditions of use.

The document will be valid for 10 years. In addition to objective information about its energy characteristics, the certificate must include recommendations for improving the energy efficiency of the property.

Peru

In Peru, the Law for the Promotion of the Efficient Use of Energy of 2000 governs.[57]​ In addition, since 2018, the General Directorate of Energy Efficiency of the Ministry of Energy and Mines supervises the energy efficiency label. Labeling is mandatory for refrigerators, washing machines, dryers, water heaters, air conditioners, light bulbs and fluorescent ballasts.[58]​.

Industries use a large amount of energy to power a wide range of manufacturing and resource extraction processes. Many industrial processes require large amounts of heat and mechanical power, most of which is supplied as natural gas, petroleum fuels, and electricity. Additionally, some industries generate fuel from waste products that can be used to provide additional energy.

Because industrial processes are so diverse, it is impossible to describe the multitude of possible opportunities for energy efficiency in industry. Many depend on the specific technologies and processes in use at each industrial facility. However, there are a number of energy processes and services that are widely used in many industries.

Several industries generate steam and electricity for later use within their facilities. When electricity is generated, the heat produced as a byproduct can be captured and used for steam processes, heating, or other industrial purposes. Conventional electricity generation is about 30% efficient, while combined heat and power (also called cogeneration) converts up to 90 percent of fuel into usable energy.[59]​.

Advanced boilers and furnaces can operate at higher temperatures while consuming less fuel. These technologies are more efficient and produce fewer pollutants.[59]​.

More than 45 percent of the fuel used by American manufacturers is burned to produce steam. Typical industrial facilities can reduce this energy use by 20 percent (according to the U.S. Department of Energy) by insulating steam and condensate return lines, stopping steam leaks, and maintaining steam traps.[59]​.

Electric motors generally run at a constant speed, but a variable speed drive allows the motor's power output to match the required load. This achieves energy savings ranging from 3 to 60 percent, depending on how the motor is used. Motor coils made of superconducting materials can also reduce energy losses. Motors can also benefit from voltage optimization. The industry uses a large number of "Compressor (machine)" pumps and compressors of all shapes and sizes and in a wide variety of applications. The efficiency of pumps and compressors depends on many factors, but improvements can often be made by implementing better process control and better maintenance practices. Compressors are commonly used to provide compressed air that is used for sandblasting, painting, and other power tools. According to the U.S. Department of Energy, optimizing compressed air systems by installing variable speed drives, along with preventive maintenance to detect and repair air leaks, can improve energy efficiency by 20 to 50 percent.[59]​.

Automobiles

The estimated energy efficiency for a car is 280 passenger miles/10 Btu.[60]​ There are several ways to improve the energy efficiency of a vehicle. Using improved aerodynamics to minimize drag can increase fuel efficiency. Reducing vehicle weight can also improve fuel economy, which is why composite materials are widely used in car bodies.

More advanced tires, with reduced tire-to-road friction and rolling resistance, can save gas. Fuel economy can be improved by up to 3.3% by keeping tires inflated to the correct pressure.[61]​ Replacing a clogged air filter can improve a car's fuel economy by up to 10 percent in older vehicles.[62]​ In newer vehicles (from the 1980s) with computer-controlled, fuel-injected engines, a clogged air filter has no effect on miles per gallon, but replacing it it can improve acceleration by 6-11 percent.[63] Aerodynamics also aid in a vehicle's efficiency. The design of a car affects the amount of gas needed to move it through the air. Aerodynamics involves the air around the car, which can affect the efficiency of the energy expended.[64]​.

Turbochargers can increase fuel efficiency by allowing a smaller displacement engine. The '2011 Engine of the Year' is a Fiat 500 engine fitted with an MHI turbocharger.

Energy-efficient vehicles can achieve twice the fuel efficiency of the average car. Cutting-edge designs, such as the Mercedes-Benz Bionic diesel concept vehicle, have achieved fuel efficiency of up to 84 miles per US gallon (2.8 L/100 km), four times the current conventional automotive average.[66]

The main trend in automotive efficiency is the increase in electric vehicles (all electric or hybrid). Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would be dissipated in regular cars; the effect is especially pronounced in urban driving.[67]​ Plug-in hybrids also have a larger battery capacity, making it possible to drive limited distances without burning gasoline; In this case, energy efficiency is dictated by whatever process (such as burning coal, hydroelectric power, or renewable source) that creates the energy. Plug-ins can typically drive for about 40 miles (64 km) purely on electricity without recharging; If the battery is running low, a gasoline engine kicks in allowing extended range. Finally, all-electric cars are also growing in popularity; The Tesla Model S sedan is the only high-performance all-electric car currently on the market.

Public lighting

Cities around the world illuminate millions of streets with 300 million lights.[68]​ Some cities are seeking to reduce the energy consumption of street lights by dimming lights during peak hours or switching to LED lamps.[69]​ It is unclear whether the high luminous efficiency of LEDs will lead to real energy reductions, as cities may end up installing additional lamps or brighter lighting areas than in the past.[70]​.

Aircraft

There are several ways to reduce energy consumption in air transport, from modifications to the aircraft themselves, to how air traffic is managed. As in cars, turbochargers are an effective way to reduce energy consumption; However, rather than allowing the use of a smaller displacement engine, turbochargers in jet turbines operate by compressing less dense air at higher altitudes. This allows the engine to operate as if at sea level pressures while taking advantage of the aircraft's reduced drag at higher altitudes.

Air traffic management systems are another way to increase the efficiency of not only the aircraft but the airline industry in general. The new technology enables superior automation of takeoff, landing and collision avoidance, as well as within airports, from simple things like HVAC and lighting to more complex tasks like security and scanning.

Alternative fuels, known as non-conventional or advanced fuels, are any materials or substances that can be used as fuels, other than conventional fuels. Some well-known alternative fuels include biodiesel, bioalcohol (methanol, ethanol, butanol), chemically stored electricity (batteries and fuel cells), hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil, and other biomass sources "Biomass (energy)").

• - Production of green diesel.

Energy conservation is broader than energy efficiency by including active efforts to reduce energy consumption, for example through behavior change&action=edit&redlink=1 "Behavior change (public health) (not yet drafted)"), as well as using energy more efficiently. Some examples of conservation without efficiency improvements are heating a room less in the winter, using your car less, air-drying clothes instead of using the dryer, or enabling energy-saving modes on a computer. As with other definitions, the boundary between efficient energy use and energy conservation may be blurred, but both are important in environmental and economic terms.[71]​ This is especially the case when actions are aimed at saving fossil fuels.[72]​ Energy conservation is a challenge that requires policy programs, technological development and behavioral change to go hand in hand. Many energy intermediary organizations, for example governmental or non-governmental organizations at the local, regional or national level, are working on programs or projects often publicly funded to address this challenge. Psychologists have also engaged with the issue of energy conservation and have provided guidelines for behavioral change to reduce energy consumption, taking into account technological and policy considerations.

The National Renewable Energy Laboratory maintains a comprehensive list of useful applications for energy efficiency.[75]​.

Commercial property managers who plan and manage energy efficiency projects typically use a software platform to conduct energy audits and collaborate with contractors to understand their full range of options. The Department of Energy (DOE) Software Directory Archived June 7, 2013, at the Wayback Machine. describes EnergyActio software, a cloud-based platform designed for this purpose.

Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed simultaneously to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the growth of energy demand, so increasing clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too quickly, renewable energy development will pursue a receding target. Likewise, unless clean energy supplies come online quickly, slowing demand growth will only begin to reduce overall carbon emissions; A reduction in the carbon content of energy sources is also needed. A sustainable energy economy therefore requires major commitments to efficiency and renewable energy.[76]​.

If demand for energy services remains constant, improving energy efficiency will reduce energy consumption and carbon emissions. However, many efficiency improvements do not reduce energy consumption by the amount predicted by simple engineering models. This is because they make energy services cheaper and therefore the consumption of those services increases. For example, since fuel-efficient vehicles make travel cheaper, consumers may choose to drive farther, thus offsetting some of the potential energy savings. Similarly, extensive historical analysis of improvements in technological efficiency has conclusively shown that improvements in energy efficiency were almost always outpaced by economic growth, resulting in a net increase in resource use and associated pollution.[77] These are examples of the direct rebound effect&action=edit&redlink=1 "Rebound effect (conservation) (not yet drafted)").

Estimates of the size of the rebound effect range from approximately 5% to 40%.[79][80][81] The rebound effect is likely to be less than 30% at the household level and may be closer to 10% for transportation.[78] A rebound effect of 30% implies that improvements in energy efficiency should achieve 70% of the reduction in energy consumption projected using engineering models. The rebound effect may be particularly large for lighting, because unlike tasks such as transportation, there is effectively no upper limit on the amount of light that could be considered useful.[82]​ In fact, it appears that lighting has accounted for approximately 0.7% of GDP over many societies for hundreds of years, implying a 100% rebound effect.[83]​.

The Rosenfeld Effect constitutes one of the paradoxes of energy efficiency at the urban territorial level and owes its name to the Physicist Dr. Arthur H. Rosenfeld. It applies to the State of California in the USA since since 1973 per capita energy demand has remained practically constant, while in the rest of the USA it has grown more than 50%. Partly due to the population's energy saving culture, but also to constant technological innovation and its acceptance by society.

Dr. Rosenfeld, born in Alabama in 1927 and based in California, was a strong promoter of energy efficiency and, among several developments, he proposed the first electronic ballast for fluorescent lighting, which led to the development of compact, low-consumption lamps.

In his honor, a unit of measurement of energy efficiency was created with the equivalence 1 Rosenfeld = consumption of 250,000 inhabitants and serves as a comparison measure between cities.

International.

• - 80 Plus.

• - 2000 watt society.

• - IEA Solar Heating and Cooling Implementation Agreement Task 13.

• - International Institute for Energy Conservation.

• - International Energy Agency (e.g. One Watt Initiative).

• - International Electrotechnical Commission.

• - International Association for Cooperation in Energy Efficiency.

• - World Sustainable Energy Days.

China.

• - National Development and Reform Commission.

• - National Center for Energy Conservation.

• - Energy Research Institute, NDRC.

Australia.

• - Department of Climate Change and Energy Efficiency.

• - Department of Environment, Water, Heritage and the Arts.

• - Sustainable House Day.

European Union.

• - Energy rating of the building.

• - Ecological design directive for products that use energy.

• - Energy efficiency in Europe (study).

• - Orgalime, the European association of engineering industries.

Finland.

• - Motivates.

Iceland.

• - Marorka.

India.

• - 88888 lights off.

• - Energy Efficiency Office.

• - Limited energy efficiency services.

Indonesia.

• - Indonesia Energy Efficiency and Conservation Society (IECES).

Japan.

• - Cool Biz Campaign.

Lebanon.

• - The Lebanese Center for Energy Conservation.

United Kingdom.

• - Thel Carbon Trust.

• - Energy saving trust.

• - National Energy Action.

• - National Energy Foundation.

• - Houses of creative energy.

• - Association of Energy Administrators.

USA.

• - Alliance to save energy.

• - American Council for an Energy Efficient Economy (ACEEE).

• - Building code assistance project.

• - Building energy code program.

• - Consortium for Energy Efficiency.

• - Energy Star, from the United States Environmental Protection Agency "Environmental Protection Agency (United States)").

• - Industrial Evaluation Center.

• - National Association of Electrical Manufacturers.

• - Rocky Mountain Institute.

• - Indian energy strategies.

• - Cogeneration.

• - Efficiency of data center infrastructure").

• - Distributed generation.

• - Electrical energy efficiency on farms in the United States").

• - Electric vehicle.

• - Energy audit.

• - Energy conservation measure.

• - Energy conversion efficiency").

• - Implementation of energy efficiency").

• - Energy recovery.

• - Energy resilience").

• - Energy storage").

• - Energy storage as a service (ESaaS).

• - EU Energy Efficiency Directive 2012/27/EU").

• - Performance per watt").

• - Lee Schipper.

• - List of energy storage projects").

• - List of power stations with the least carbon emissions").

• - Passenger miles per gallon").

• - Oil peak").

• - Renewable energy.

• - Renewable heat").

• - Reserve power").

• - United States Department of Energy Solar Decathlon").

• - The Green Deal").

• - World Congress of Energy Engineering").

• - Energy reduction assets").

• - John A. "Skip" Laitner").

• - Passive house.

• - Light pollution").

• - Energy efficient building.

Energy efficiency has proven to be a cost-effective strategy for building economies without necessarily increasing energy consumption. For example, the state of California began implementing energy efficiency measures in the mid-1970s, including building codes and appliance standards with strict efficiency requirements. Over the years since, California's energy consumption has remained roughly flat on a per capita basis, while U.S. national consumption doubled. As part of its strategy, California implemented a "charging order" for new energy resources that puts energy efficiency first, renewable electricity supply second, and new fossil fuel power plants. States such as Connecticut and New York have created quasi-public green banks to help owners of residential and commercial buildings finance improvements. energy efficiency that reduce emissions and reduce energy costs for consumers.[8]​.

Lovin's Rocky Mountain Institute notes that, in industrial settings, "abundant opportunities exist to save 70% to 90% of the energy and cost of lighting systems, fans, and pumps; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances. Overall, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less. As with electricity itself, the same applies to home settings. The US Department of Energy has stated that there is potential for energy savings in the magnitude of 90 billion kWh by increasing home energy efficiency.[9]​.

Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute stated that "there are enough economically viable opportunities to improve energy productivity that could keep global energy demand growth at less than 1 percent annually," less than half the average of 2.2 percent. Expected growth through 2020 in a business-as-usual scenario.[10]​ Energy productivity, which measures the production and quality of goods and services per unit of energy input, can come from reducing the amount of energy required to produce something or from increasing the quantity or quality of goods and services for the same amount of energy. .

The 2007 Vienna Climate Change Report, sponsored by the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows that "energy efficiency can achieve true emissions reductions at low cost."[11]​.

International standards ISO 17743 and ISO 17742 provide a documented methodology for calculating and reporting energy savings and energy efficiency for countries and cities.[12]​[13]​.

From an energy consumer's point of view, the primary motivation for energy efficiency is often simply to save money by reducing the cost of purchasing energy. Furthermore, from an energy policy point of view, there has been a long trend in a broader recognition of energy efficiency as the "first fuel", that is, the ability to replace or avoid the consumption of real fuels. In fact, the International Energy Agency has calculated that the implementation of energy efficiency measures in the years 1974-2010 has prevented more energy consumption in its Member States than the consumption of any particular fuel, including oil, coal and natural gas.[14]​.

In addition, it has long been recognized that energy efficiency brings additional benefits to reducing energy consumption.[15] Some estimates of the value of these other benefits, often called multiple benefits, complementary benefits, ancillary benefits or non-energy benefits, have put their total value even higher than that of the direct energy benefits.[16] These multiple benefits of energy efficiency include things such as reducing the impact of climate change, reducing air pollution and improving health, improving living conditions. interiors, improving energy security and reducing price risk for energy consumers. Methods have been developed to calculate the monetary value of these multiple benefits, including, for example, the experimental method of choice for improvements that have a subjective component (such as aesthetics or comfort)[14]​ and the Tuominen-Seppänen method for price risk reduction.[17]​ When included in the analysis, the economic benefit of investments in energy efficiency can be shown to be significantly greater than simply the value of the energy saved.[14]​.

Contenido

La calefacción puede ser objeto de ahorro de energía principalmente con hábitos de consumo tales como un uso racional del mismo, el consumo total de una vivienda suele ser del 46 % del total del consumo[18]​ (pudiendo alcanzar el 60 % si se incluye el agua caliente). El ahorro de energía puede producirse bien por la correcta elección de una caldera "Caldera (calefacción)") eficiente, o por el correcto aislamiento térmico de las habitaciones.

Respecto del agua caliente puede emplearse también como ayuda la energía solar térmica, mediante uso de sistemas de almacenamiento de energía que retengan el calor para que el agua caliente esté disponible la mayor parte de tiempo posible. Así mismo, se puede ahorrar energía dotando a los grifos y lavado de perlizadores") y a las duchas con reductores volumétricos de caudal o alcachofas de mano eco-eficientes. De esta forma se puede reducir el consumo de la energía empleada en calentar agua en más del 40%. Si al inodoro se le instala un mecanismo de doble pulsador, el ahorro de agua puede ser superior al 70%, pero en este caso no se ahorra energía, ya que, el inodoro sólo usa agua fría.

Se debe tener presente que una temperatura para un hogar está entre los 19 y los 21 °C por el día, y 15 a 17 °C por la noche, cada grado aumenta el consumo en un 7%.[19]​ Con estas consideraciones se aconseja:.

• - Adecuar el vestido en el domicilio con las condiciones de temperatura, se pueden emplear edredones, mantas y prendas similares.

• - No tapar u obstruir los radiadores ya que su función es la de emitir calor, y esta se ve entorpecida con la colocación de muebles.

• - Vigilar el aislamiento de las habitaciones, impidiendo fugas de calor o entradas de aire frío procedente de ventanas abiertas.

El empleo del agua caliente se realiza en la vivienda bajo ciertas ocasiones muy específicas como puede ser la ducha, o el baño, limpiando los platos y la cubertería, etc. En todos ellos se aconseja emplear agua caliente sólo cuando se necesite, al lavar no siempre se necesita.

Appliances

Modern appliances, such as freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use much less energy than older appliances. Installing a clothesline will significantly reduce energy consumption as the dryer will be used less. Current energy-efficient refrigerators, for example, use 40 percent less energy than conventional models in 2001. After this, if all households in Europe replaced their appliances older than ten years with new ones, 20 billion kWh of electricity would be saved annually, which would reduce CO emissions by almost 18 billion kg.[20]​ In the United States, the corresponding figures would be 17 billion kWh of electricity and 27 000,000,000 pounds (12,246,984,000 kg) CO.[21]​ According to a 2009 study by McKinsey & Company, replacing old appliances is one of the most efficient global measures to reduce greenhouse gas emissions.[22]​ Modern energy management systems also reduce the energy use of idle devices by turning them off or putting them in a low-power mode. after a certain time. Many countries identify energy efficient appliances that use energy input labels.[23]​.

The impact of energy efficiency on peak demand depends on when the appliance is used. For example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an energy efficient air conditioner will have a greater impact on peak demand than off-peak demand. An energy-efficient dishwasher, on the other hand, uses more energy at night when people wash their dishes. This device may have little or no impact on peak demand.

Buildings are an important area for energy efficiency improvements worldwide due to their role as a major consumer of energy. However, the issue of energy use in buildings is not simple, since the indoor conditions that can be achieved with energy use vary greatly. The measures that make buildings comfortable – lighting, heating, cooling and ventilation – consume energy. Typically, the level of energy efficiency in a building is measured by dividing the energy consumed with the floor area of ​​the building which is known as specific energy consumption (SEC) or energy use intensity (EUI):[26]​.

However, the problem is more complex since construction materials have incorporated energy into them. On the other hand, energy can be recovered from materials when the building is dismantled by reusing the materials or burning them for energy. Additionally, when the building is used, interior conditions may vary, resulting in higher and lower quality interior environments. Finally, overall efficiency is affected by the use of the building: is the building occupied most of the time and are the spaces used efficiently, or is the building largely empty? It has even been suggested that for a more complete accounting of energy efficiency, the SEC should be amended to include these factors:[27]​.

Therefore, a balanced approach to energy efficiency in buildings should be more comprehensive than simply trying to minimize the energy consumed. Issues such as the quality of the indoor environment and the efficiency of space use must be taken into account. Measures used to improve energy efficiency can therefore take many different forms. They often include passive measures that inherently reduce the need to use energy, such as better insulation. Many serve several functions that improve indoor conditions and reduce energy use, such as increasing the use of natural light.

The location and environment of a building play a key role in regulating its temperature and lighting. For example, trees, landscaping, and hills can provide shade and block wind. In colder climates, designing northern hemisphere buildings with south-facing windows and southern hemisphere buildings with north-facing windows increases the amount of sun (ultimately thermal energy) entering the building, minimizing energy use, by maximizing passive solar heating. Compact building design, including energy-efficient windows, well-sealed doors, and additional thermal insulation of walls, basement slabs, and foundation can reduce heat loss by 25 to 50 percent.[23][28]​.

Dark ceilings can be up to 70°F (39°C) warmer than more reflective white surfaces. They transmit some of this extra heat into the building. US studies have shown that light-colored roofs use 40 percent less energy for cooling than buildings with darker roofs. White roof systems save more energy in sunnier climates. Advanced electronic heating and cooling systems can moderate energy consumption and improve the comfort of people in the building.[23]​.

Proper placement of windows and skylights, as well as the use of light-reflecting architectural features in a building can reduce the need for artificial lighting. One study has shown that increasing the use of natural and task lighting increases productivity in schools and offices.[23] Compact fluorescent lamps use two-thirds less energy and can last 6 to 10 times longer than incandescent bulbs. Newer fluorescent lights produce natural light, and in most applications are cost effective, despite their higher initial cost, with payback periods as low as a few months. LED lamps use only about 10% of the energy required by an incandescent lamp.

Effective energy-efficient building design can include using low-cost passive infrared (PIR) to turn off lighting when areas are unoccupied, such as toilets, hallways, or even office areas after hours. Additionally, lux levels can be monitored using daylight sensors linked to the building's lighting scheme to turn lighting on/off or dim to predefined levels to take into account natural light and thus reduce consumption. Building management systems (BMS) link all of this into a centralized computer to control the lighting and energy requirements of the entire building.[29]​.

In an analysis that integrates a residential bottom-up simulation with an economic multi-sector model, it has been shown that variable heat gains caused by insulation and air conditioning efficiency can have non-uniform load shifting effects on electrical load. The study also highlighted the impact of greater household efficiency on the electricity generation capacity choices made by the electricity sector.[30]​.

The choice of space heating or cooling technology to use in buildings can have a significant impact on energy use and efficiency. For example, replacing an old natural gas furnace with 50% efficiency with a new one with 95% efficiency will dramatically reduce energy consumption, carbon emissions, and natural gas bills in the winter. Ground source heat pumps can be even more energy efficient and cost effective. These systems use pumps and compressors to move refrigerant fluid around a thermodynamic cycle in order to "pump" heat against its natural flow from hot to cold, in order to transfer heat to a building from the large thermal reservoir contained within the nearby ground. The end result is that heat pumps typically use four times less electrical energy to supply an equivalent amount of heat than a direct electric heater. Another advantage of a ground source heat pump is that it can be reversed in summer and operate to cool the air by transferring heat from the building to the ground. The disadvantage of ground source heat pumps is their high initial capital cost, but this is usually paid back within five to ten years as a result of lower energy use.

Smart meters are slowly being adopted by the commercial sector for staff highlighting and for internal monitoring purposes of building energy usage in a dynamic presentable format. The use of power quality analyzers can be introduced into an existing building to evaluate usage, harmonic distortion, spikes, surges, interruptions, among others, to ultimately make the building more energy efficient. Often such meters communicate using wireless sensor networks.

Green Building XML") (gbXML) is an emerging schema, a subset of Building Information Modeling efforts, focused on the design and operation of green buildings. gbXML is used as input in several energy simulation engines. But with the development of modern computer technology, there are a large number of building performance simulation tools available on the market. When choosing which simulation tool to use in a project, the user must consider the accuracy and reliability of the tool, taking into account the building information they have on hand, which will serve as input for the tool. Yezioro, Dong and Leite[31]​ developed an artificial intelligence approach to evaluate the building performance simulation results and found that the most detailed simulation tools have the best simulation performance in terms of heating and cooling electricity consumption within 3% of the mean absolute error.

Leadership in Energy and Environmental Design (LEED) is a rating system organized by the US Green Building Council (USGBC) to promote environmental responsibility in building design. They currently offer four levels of certification for existing buildings (LEED-EBOM) and new construction (LEED-NC) based on a building's compliance with the following criteria: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Design Innovation. In 2013, USGBC developed the LEED Dynamic Plaque, a tool to track building performance against LEED metrics and a potential path to recertification. collaborated with Honeywell to collect data on energy and water usage, as well as indoor air quality from a BAS to automatically update the board, providing a near real-time view of performance. The USGBC office in Washington, D.C., is one of the first buildings to feature the live-updating LEED dynamic board.[33]​.

A deep energy retrofit is a whole-building analysis and construction process that is used to achieve much greater energy savings than conventional energy retrofits. Deep energy retrofits can be applied to residential and non-residential ("commercial") buildings. A deep energy retrofit typically results in energy savings of 30 percent or more, perhaps spread over several years, and can significantly improve the value of the building.[34] The Empire State Building has undergone a deep energy retrofit process that is completed in 2013. The project team, comprised of representatives from Johnson Controls, Rocky Mountain Institute, Clinton Climate Initiative, and Jones Lang LaSalle, will have achieved a 38%, $4.4 million annual energy use reduction. For example, the 6,500 windows were remanufactured on-site into "super windows" that block heat but let in light. Air conditioning operating costs on hot days were reduced and this saved $17 million off the project's capital cost immediately, partly funding other repairs.[36]​ Receiving a Leadership in Energy and Environmental Design (LEED) gold rating in September 2011, the Empire State Building is the tallest LEED-certified building in the United States.[24]​ The Indianapolis City-County Building recently underwent a renovation process. deep energy retrofit, which has achieved a 46% annual energy reduction and $750,000 annual energy savings.

Energy retrofits, including deep retrofits, and other types performed in residential, commercial, or industrial locations are typically supported through various forms of financing or incentives. Incentives include pre-packaged refunds where the buyer/user may not even know that the item being used has been refunded or "purchased." “Upstream” or “midstream” purchases are common for efficient lighting products. Other discounts are more explicit and transparent to the end user through the use of formal applications. In addition to rebates, which may be offered through government or utility programs, governments sometimes offer tax incentives for energy efficiency projects. Some entities offer rebate and payment facilitation and guidance services that enable energy end-use customers to take advantage of incentive and incentive programs.

To evaluate the economic soundness of energy efficiency investments in buildings, cost-effectiveness analysis or CEA can be used. A CEA calculation will produce the value of the energy saved, sometimes called negawatts, in $/kWh. The energy in such a calculation is virtual in the sense that it was never consumed but was saved due to an investment in energy efficiency. CEA therefore allows the price of negawatts to be compared to the price of energy, such as electricity from the grid or the cheapest renewable alternative. The benefit of the CEA approach in energy systems is that it avoids the need to guess at future energy prices for calculation purposes, thus eliminating the main source of uncertainty in the evaluation of energy efficiency investments.[37]​.

Europe

In Europe, energy efficiency targets have been set for 2020 and 2030.

The first EU-wide target was set in 1998. Member States agreed to improve energy efficiency by 1 percent per year for twelve years. In addition, legislation on products, industry, transport and buildings has contributed to an overall energy efficiency framework. Greater effort is needed to address heating and cooling: more heat is wasted during electricity production in Europe than is required to heat all buildings on the continent.[38]​ Overall, EU energy efficiency legislation is estimated to deliver savings equivalent to up to 326 million tonnes of oil per year by 2020.[39]​.

The EU set an energy savings target of 20% by 2020 compared to 1990 levels, but Member States decide individually how energy savings will be achieved. At an EU summit in October 2014, EU countries agreed on a new energy efficiency target of 27% or more by 2030. One mechanism used to achieve the 27% target is "Supplier Obligations and Blank Certificates".[40] The ongoing debate around the 2016 Clean Energy Package also places emphasis on energy efficiency, but the target will likely remain around 30% more efficient compared with 1990 levels.[39] Some have argued that this will not be enough for the EU to meet the Paris Agreement goals of reducing greenhouse gas emissions by 40% compared to 1990 levels.

Australia

The Australian national government is actively leading the country in efforts to increase its energy efficiency, primarily through the government's Department of Industry and Science. In July 2009, the Council of Australian Governments, representing Australia's states and territories, agreed on a National Strategy on Energy Efficiency (NSEE).[41]​.

This is a ten-year plan that accelerates the implementation of a nationwide adoption of energy efficiency practices and a preparation for the country's transformation to a low-carbon future. There are several different areas of energy use addressed within the NSEE. However, the chapter dedicated to the approach to energy efficiency to be adopted at national level highlights four points in achieving the declared levels of energy efficiency. Are:.

• - To help households and businesses transition to a low carbon future.

• - Expedite the adoption of efficient energy.

• - Make buildings more energy efficient.

• - For governments to work in partnership and lead the way towards energy efficiency.

The main agreement governing this strategy is the National Partnership Agreement on Energy Efficiency.[42]​.

This document also explains the role of the community and individual states and territories in the NSEE, as well as the creation of benchmarks and measurement devices that will transparently show the nation's progress against the stated objectives, and addresses the need for funding the strategy to enable it to move forward.

Canada

In August 2017, the Government of Canada launched Build Smart – Canada's Buildings Strategy, as a key driver of the Pan-Canadian Framework on Clean Growth and Climate Change, Canada's national climate strategy.

The Build Smart strategy seeks to dramatically increase the energy efficiency performance of new and existing Canadian buildings, and sets five goals to that end:.

• - Federal, provincial and territorial governments will work to develop and adopt increasingly stringent model building codes, beginning in 2020, with the goal of provinces and territories adopting a "net zero energy" model building code by 2030.

• - Federal, provincial and territorial governments will work to develop a model code for existing buildings by 2022, with the goal of provinces and territories adopting the code.

• - Federal, provincial and territorial governments will work together with the goal of requiring labeling of construction energy use starting in 2019.

• - The federal government will set new standards for heating equipment and other key technologies at the highest level of efficiency that is economically and technically achievable.

• - Provincial and territorial governments will work to maintain and expand efforts to modernize existing buildings by supporting energy efficiency improvements and accelerating the adoption of high-efficiency equipment while adapting their programs to regional circumstances.

The strategy details a range of activities that the Government of Canada will undertake, and the investments it will make, to support the objectives. As of early 2018, only one of Canada's 10 provinces and three territories, British Columbia, has developed policy in support of the federal government's goal of achieving net-zero energy ambitions: the BC Energy Steps Code.

Local governments in British Columbia can use BC Energy's Code Steps, if they wish, to incentivize or require a level of energy efficiency in new construction that goes beyond the base building code requirements. The regulation and standard are designed as a technical roadmap to help the province achieve its goal that all new buildings will achieve a net-zero energy performance level by 2032.

Germany

Energy efficiency is central to energy policy in Germany.[43]​ At the end of 2015, the national policy includes the following efficiency and consumption targets (with actual values ​​for 2014):[44]​.

Recent progress towards greater efficiency has been steady, apart from the financial crisis of 2007–08.[45]​ However, some believe that energy efficiency is still not recognized in terms of its contribution to Germany's energy transformation (or Energiewende).[46]​.

Efforts to reduce final energy consumption in the transport sector have not been successful, with growth of 1.7% between 2005-2014. This growth is due to both road passenger transport and road freight transport. Both sectors increased the total distance traveled to record the highest figures in Germany. Rebound effects played an important role, both between improved vehicle efficiency and distance traveled, and between improved vehicle efficiency and an increase in vehicle weight and engine power.[47]​.

On December 3, 2014, the German federal government launched its National Action Plan on Energy Efficiency (NAPE).[48]​[49]​ The areas covered are energy efficiency of buildings, energy conservation for businesses, consumer energy efficiency and energy efficiency of transport. The policy contains immediate and future measures. NAPE's short-term core measures include the introduction of competitive tendering for energy efficiency, raising funds for building renovation, introducing tax incentives for efficiency measures in the construction sector and establishing energy efficiency networks together with business and industry. German industry is expected to make a considerable contribution.

On August 12, 2016, the German government published a green paper on energy efficiency for public consultation (in German).[50]​[51]​ It describes possible challenges and actions needed to reduce energy consumption in Germany in the coming decades. At the launch of the document, Economy and Energy Minister Sigmar Gabriel said that "we do not need to produce, store, transmit and pay for the energy we save."[50]​ The Green Paper prioritizes efficient energy use as the "first" response and also outlines opportunities for sector coupling, including the use of renewable energy for heating and transport.[50]​ Other proposals include a flexible energy tax that increases as gasoline prices fall, incentivizing fuel conservation despite low oil prices.[52]​.

Poland

In May 2016, Poland adopted a new Energy Efficiency Law, which came into force on October 1, 2016.[53]​.

USA

A 2011 Energy Modeling Forum study covering the United States examines how energy efficiency opportunities will shape future fuel and electricity demand in the coming decades. The U.S. economy is now ready to reduce its energy and carbon intensity, but explicit policies will be needed to meet climate goals. These policies include: a carbon tax, mandatory standards for more efficient appliances, buildings and vehicles, and subsidies or reductions in the initial costs of new, more energy-efficient equipment.[54]​.

Argentina

In 2016, the Argentine Institute for Standardization and Certification approved the IRAM Standard 11900 "Heating energy efficiency label for buildings". The aforementioned standard establishes a simplified methodology for calculating the level of energy efficiency of the envelope of buildings that can be heated. The results are displayed on a label, similar to that used to rate the energy efficiency of domestic appliances (refrigerators, washing machines, lamps, etc.). The thermal efficiency of the envelope is directly related to the thermal transmittance of the materials that form the building envelope. The standard establishes 8 levels of thermal efficiency of the envelope, from "A- green" with the most optimal efficiency to "H- brown" the least efficient. The class is determined by calculating the weighted average variation in temperature between the interior surface of each component of the envelope and the interior design temperature (20 °C).

Venezuela

64% of the electricity in the country is generated by waterfalls. There are 96 reservoirs in Venezuela, which store about 157 km of water. The Caroní River basin is the main electricity generator in the country, currently producing 24,229 Mega Watts (MW) of electrical potential, which represents 75% of the country's current total potential. Its extension is 92,170 km, towards the right bank of the Orinoco River (Guyana Region). This potential is exploited through the Guri, Caruachi and Macagua dams and soon the Tocoma dam (in the final stage of feasibility studies and preparation of the land for its construction). From 1963 to today, the electrical development of the lower Caroní has ​​allowed the country to save the consumption of 2,173 million barrels of oil equivalent. Tocoma would add about 2,250 MW of additional electrical power to the national grid from renewable energy sources, which if generated through thermoelectric plants, would represent a daily consumption of approximately 68,000 barrels of oil per day.

Spain

The Energy Efficiency Directive in buildings has been transposed in Spain through the Comprehensive Housing and Land Plan").[55]​[56]​.

According to this regulation, since June 1, 2013, it is mandatory that all properties that are sold or rented for a period of more than four months have an energy label obtained through a technical study or energy certification.

The energy label of the buildings will show a letter rating that will vary from A to G. The assessment will be based on the CO emitted by the energy consumption of the heating, cooling, domestic hot water and lighting installations of the building under certain conditions of use.

The document will be valid for 10 years. In addition to objective information about its energy characteristics, the certificate must include recommendations for improving the energy efficiency of the property.

Peru

In Peru, the Law for the Promotion of the Efficient Use of Energy of 2000 governs.[57]​ In addition, since 2018, the General Directorate of Energy Efficiency of the Ministry of Energy and Mines supervises the energy efficiency label. Labeling is mandatory for refrigerators, washing machines, dryers, water heaters, air conditioners, light bulbs and fluorescent ballasts.[58]​.

Industries use a large amount of energy to power a wide range of manufacturing and resource extraction processes. Many industrial processes require large amounts of heat and mechanical power, most of which is supplied as natural gas, petroleum fuels, and electricity. Additionally, some industries generate fuel from waste products that can be used to provide additional energy.

Because industrial processes are so diverse, it is impossible to describe the multitude of possible opportunities for energy efficiency in industry. Many depend on the specific technologies and processes in use at each industrial facility. However, there are a number of energy processes and services that are widely used in many industries.

Several industries generate steam and electricity for later use within their facilities. When electricity is generated, the heat produced as a byproduct can be captured and used for steam processes, heating, or other industrial purposes. Conventional electricity generation is about 30% efficient, while combined heat and power (also called cogeneration) converts up to 90 percent of fuel into usable energy.[59]​.

Advanced boilers and furnaces can operate at higher temperatures while consuming less fuel. These technologies are more efficient and produce fewer pollutants.[59]​.

More than 45 percent of the fuel used by American manufacturers is burned to produce steam. Typical industrial facilities can reduce this energy use by 20 percent (according to the U.S. Department of Energy) by insulating steam and condensate return lines, stopping steam leaks, and maintaining steam traps.[59]​.

Electric motors generally run at a constant speed, but a variable speed drive allows the motor's power output to match the required load. This achieves energy savings ranging from 3 to 60 percent, depending on how the motor is used. Motor coils made of superconducting materials can also reduce energy losses. Motors can also benefit from voltage optimization. The industry uses a large number of "Compressor (machine)" pumps and compressors of all shapes and sizes and in a wide variety of applications. The efficiency of pumps and compressors depends on many factors, but improvements can often be made by implementing better process control and better maintenance practices. Compressors are commonly used to provide compressed air that is used for sandblasting, painting, and other power tools. According to the U.S. Department of Energy, optimizing compressed air systems by installing variable speed drives, along with preventive maintenance to detect and repair air leaks, can improve energy efficiency by 20 to 50 percent.[59]​.

Automobiles

The estimated energy efficiency for a car is 280 passenger miles/10 Btu.[60]​ There are several ways to improve the energy efficiency of a vehicle. Using improved aerodynamics to minimize drag can increase fuel efficiency. Reducing vehicle weight can also improve fuel economy, which is why composite materials are widely used in car bodies.

More advanced tires, with reduced tire-to-road friction and rolling resistance, can save gas. Fuel economy can be improved by up to 3.3% by keeping tires inflated to the correct pressure.[61]​ Replacing a clogged air filter can improve a car's fuel economy by up to 10 percent in older vehicles.[62]​ In newer vehicles (from the 1980s) with computer-controlled, fuel-injected engines, a clogged air filter has no effect on miles per gallon, but replacing it it can improve acceleration by 6-11 percent.[63] Aerodynamics also aid in a vehicle's efficiency. The design of a car affects the amount of gas needed to move it through the air. Aerodynamics involves the air around the car, which can affect the efficiency of the energy expended.[64]​.

Turbochargers can increase fuel efficiency by allowing a smaller displacement engine. The '2011 Engine of the Year' is a Fiat 500 engine fitted with an MHI turbocharger.

Energy-efficient vehicles can achieve twice the fuel efficiency of the average car. Cutting-edge designs, such as the Mercedes-Benz Bionic diesel concept vehicle, have achieved fuel efficiency of up to 84 miles per US gallon (2.8 L/100 km), four times the current conventional automotive average.[66]

The main trend in automotive efficiency is the increase in electric vehicles (all electric or hybrid). Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would be dissipated in regular cars; the effect is especially pronounced in urban driving.[67]​ Plug-in hybrids also have a larger battery capacity, making it possible to drive limited distances without burning gasoline; In this case, energy efficiency is dictated by whatever process (such as burning coal, hydroelectric power, or renewable source) that creates the energy. Plug-ins can typically drive for about 40 miles (64 km) purely on electricity without recharging; If the battery is running low, a gasoline engine kicks in allowing extended range. Finally, all-electric cars are also growing in popularity; The Tesla Model S sedan is the only high-performance all-electric car currently on the market.

Public lighting

Cities around the world illuminate millions of streets with 300 million lights.[68]​ Some cities are seeking to reduce the energy consumption of street lights by dimming lights during peak hours or switching to LED lamps.[69]​ It is unclear whether the high luminous efficiency of LEDs will lead to real energy reductions, as cities may end up installing additional lamps or brighter lighting areas than in the past.[70]​.

Aircraft

There are several ways to reduce energy consumption in air transport, from modifications to the aircraft themselves, to how air traffic is managed. As in cars, turbochargers are an effective way to reduce energy consumption; However, rather than allowing the use of a smaller displacement engine, turbochargers in jet turbines operate by compressing less dense air at higher altitudes. This allows the engine to operate as if at sea level pressures while taking advantage of the aircraft's reduced drag at higher altitudes.

Air traffic management systems are another way to increase the efficiency of not only the aircraft but the airline industry in general. The new technology enables superior automation of takeoff, landing and collision avoidance, as well as within airports, from simple things like HVAC and lighting to more complex tasks like security and scanning.

Alternative fuels, known as non-conventional or advanced fuels, are any materials or substances that can be used as fuels, other than conventional fuels. Some well-known alternative fuels include biodiesel, bioalcohol (methanol, ethanol, butanol), chemically stored electricity (batteries and fuel cells), hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil, and other biomass sources "Biomass (energy)").

• - Production of green diesel.

Energy conservation is broader than energy efficiency by including active efforts to reduce energy consumption, for example through behavior change&action=edit&redlink=1 "Behavior change (public health) (not yet drafted)"), as well as using energy more efficiently. Some examples of conservation without efficiency improvements are heating a room less in the winter, using your car less, air-drying clothes instead of using the dryer, or enabling energy-saving modes on a computer. As with other definitions, the boundary between efficient energy use and energy conservation may be blurred, but both are important in environmental and economic terms.[71]​ This is especially the case when actions are aimed at saving fossil fuels.[72]​ Energy conservation is a challenge that requires policy programs, technological development and behavioral change to go hand in hand. Many energy intermediary organizations, for example governmental or non-governmental organizations at the local, regional or national level, are working on programs or projects often publicly funded to address this challenge. Psychologists have also engaged with the issue of energy conservation and have provided guidelines for behavioral change to reduce energy consumption, taking into account technological and policy considerations.

The National Renewable Energy Laboratory maintains a comprehensive list of useful applications for energy efficiency.[75]​.

Commercial property managers who plan and manage energy efficiency projects typically use a software platform to conduct energy audits and collaborate with contractors to understand their full range of options. The Department of Energy (DOE) Software Directory Archived June 7, 2013, at the Wayback Machine. describes EnergyActio software, a cloud-based platform designed for this purpose.

Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed simultaneously to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the growth of energy demand, so increasing clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too quickly, renewable energy development will pursue a receding target. Likewise, unless clean energy supplies come online quickly, slowing demand growth will only begin to reduce overall carbon emissions; A reduction in the carbon content of energy sources is also needed. A sustainable energy economy therefore requires major commitments to efficiency and renewable energy.[76]​.

If demand for energy services remains constant, improving energy efficiency will reduce energy consumption and carbon emissions. However, many efficiency improvements do not reduce energy consumption by the amount predicted by simple engineering models. This is because they make energy services cheaper and therefore the consumption of those services increases. For example, since fuel-efficient vehicles make travel cheaper, consumers may choose to drive farther, thus offsetting some of the potential energy savings. Similarly, extensive historical analysis of improvements in technological efficiency has conclusively shown that improvements in energy efficiency were almost always outpaced by economic growth, resulting in a net increase in resource use and associated pollution.[77] These are examples of the direct rebound effect&action=edit&redlink=1 "Rebound effect (conservation) (not yet drafted)").

Estimates of the size of the rebound effect range from approximately 5% to 40%.[79][80][81] The rebound effect is likely to be less than 30% at the household level and may be closer to 10% for transportation.[78] A rebound effect of 30% implies that improvements in energy efficiency should achieve 70% of the reduction in energy consumption projected using engineering models. The rebound effect may be particularly large for lighting, because unlike tasks such as transportation, there is effectively no upper limit on the amount of light that could be considered useful.[82]​ In fact, it appears that lighting has accounted for approximately 0.7% of GDP over many societies for hundreds of years, implying a 100% rebound effect.[83]​.

The Rosenfeld Effect constitutes one of the paradoxes of energy efficiency at the urban territorial level and owes its name to the Physicist Dr. Arthur H. Rosenfeld. It applies to the State of California in the USA since since 1973 per capita energy demand has remained practically constant, while in the rest of the USA it has grown more than 50%. Partly due to the population's energy saving culture, but also to constant technological innovation and its acceptance by society.

Dr. Rosenfeld, born in Alabama in 1927 and based in California, was a strong promoter of energy efficiency and, among several developments, he proposed the first electronic ballast for fluorescent lighting, which led to the development of compact, low-consumption lamps.

In his honor, a unit of measurement of energy efficiency was created with the equivalence 1 Rosenfeld = consumption of 250,000 inhabitants and serves as a comparison measure between cities.

International.

• - 80 Plus.

• - 2000 watt society.

• - IEA Solar Heating and Cooling Implementation Agreement Task 13.

• - International Institute for Energy Conservation.

• - International Energy Agency (e.g. One Watt Initiative).

• - International Electrotechnical Commission.

• - International Association for Cooperation in Energy Efficiency.

• - World Sustainable Energy Days.

China.

• - National Development and Reform Commission.

• - National Center for Energy Conservation.

• - Energy Research Institute, NDRC.

Australia.

• - Department of Climate Change and Energy Efficiency.

• - Department of Environment, Water, Heritage and the Arts.

• - Sustainable House Day.

European Union.

• - Energy rating of the building.

• - Ecological design directive for products that use energy.

• - Energy efficiency in Europe (study).

• - Orgalime, the European association of engineering industries.

Finland.

• - Motivates.

Iceland.

• - Marorka.

India.

• - 88888 lights off.

• - Energy Efficiency Office.

• - Limited energy efficiency services.

Indonesia.

• - Indonesia Energy Efficiency and Conservation Society (IECES).

Japan.

• - Cool Biz Campaign.

Lebanon.

• - The Lebanese Center for Energy Conservation.

United Kingdom.

• - Thel Carbon Trust.

• - Energy saving trust.

• - National Energy Action.

• - National Energy Foundation.

• - Houses of creative energy.

• - Association of Energy Administrators.

USA.

• - Alliance to save energy.

• - American Council for an Energy Efficient Economy (ACEEE).

• - Building code assistance project.

• - Building energy code program.

• - Consortium for Energy Efficiency.

• - Energy Star, from the United States Environmental Protection Agency "Environmental Protection Agency (United States)").

• - Industrial Evaluation Center.

• - National Association of Electrical Manufacturers.

• - Rocky Mountain Institute.

• - Indian energy strategies.

• - Cogeneration.

• - Efficiency of data center infrastructure").

• - Distributed generation.

• - Electrical energy efficiency on farms in the United States").

• - Electric vehicle.

• - Energy audit.

• - Energy conservation measure.

• - Energy conversion efficiency").

• - Implementation of energy efficiency").

• - Energy recovery.

• - Energy resilience").

• - Energy storage").

• - Energy storage as a service (ESaaS).

• - EU Energy Efficiency Directive 2012/27/EU").

• - Performance per watt").

• - Lee Schipper.

• - List of energy storage projects").

• - List of power stations with the least carbon emissions").

• - Passenger miles per gallon").

• - Oil peak").

• - Renewable energy.

• - Renewable heat").

• - Reserve power").

• - United States Department of Energy Solar Decathlon").

• - The Green Deal").

• - World Congress of Energy Engineering").

• - Energy reduction assets").

• - John A. "Skip" Laitner").

• - Passive house.

• - Light pollution").

• - Energy efficient building.