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Energy conservation

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For the physical concepts, see conservation of energy and energy efficiency.

Energy Conservation is the practice of decreasing the quantity of energy used while achieving a similar outcome of end use. This practise may result in increase of national security, personal security, financial capital, human comfort and environmental value. Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote environmental values. Industrial and commercial users may want to increase efficiency and maximize profit.

On a larger scale, energy conservation is an element of energy policy. The need to increase the available supply of energy (for example, through the creation of new power plants, or by the importation of more energy) is lessened if societal demand for energy can be reduced, or if growth in demand can be slowed. This makes energy conservation an important part of the debate over climate change and the replacement of non-renewable resources with renewable energy. Encouraging energy conservation among consumers is often advocated as a cheaper or more environmentally sensitive alternative to increased energy production.

The U.S. is by far the biggest consumer of energy in the world. The U.S. Department of Energy categorizes national energy use in four broad sectors: transportation, residential, commercial, and industrial. [1]

Energy usage in the 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, government entities and other facility managers. National energy policy has a significant effect on energy usage across all four sectors.

Transportation sector

The transportation sector includes all vehicles used for personal or freight transportation. Of the energy used in this sector, approximately 65% is consumed by gasoline-powered vehicles, primarily personally owned. Diesel-powered transport (trains, merchant ships, heavy trucks, etc.) consumes about 20%, and air traffic consumes most of the remaining 15%. [2]

The oil supply crises of the 1970s spurred the creation, in 1975, of the federal Corporate Average Fuel Economy (CAFE) program, which required auto manufacturers to meet progressively higher fleet fuel economy targets. The next decade saw dramatic improvements in fuel economy, mostly the result of reductions in vehicle size and weight. These gains eroded somewhat after 1990 due to the growing popularity of sport utility vehicles, full-size pickup trucks and minivans, which fall under the more lenient "light truck" CAFE standard.

In addition to the CAFE program, the U.S. government has tried to encourage better vehicle efficiency through tax policy. Since 2002, taxpayers have been eligible for income tax credits for gas/electric hybrid vehicles. A "gas-guzzler" tax has been assessed on manufacturers since 1978 for cars with exceptionally poor fuel economy. While this tax remains in effect, it currently generates very little revenue as overall fuel economy has improved.

Another focus in gasoline conservation is reducing the number of miles driven. An estimated 40% of American automobile use is associated with daily commuting. Many urban areas offer subsidized public transportation to reduce commuting traffic, and encourage carpooling by providing designated high-occupancy vehicle lanes and lower tolls for cars with multiple riders.

Driving at high speed reduces fuel efficiency. Gasoline-powered cars operate with maximum efficiency in the highest gear at the lowest speed in that highest gear without engine lugging, usually between 50-70 MPH.

In recent years telecommuting has also become a viable alternative to commuting for some jobs, but as of 2003 only 3.5% of workers were telecommuters. Ironically, hundreds of thousands of U.S. and European workers have been replaced by workers in India who telecommute from thousands of miles away.

Residential sector

The residential sector refers to all private residences, including single-family homes, apartments, manufactured homes and dormitories. Energy use in this sector varies significantly across the country, due to regional climate differences and different regulation. On average, about half of the energy used in the U.S. homes is expended on space conditioning (i.e. heating and cooling).

The efficiency of furnaces and air conditioners has increased steadily since the energy crises of the 1970s. The 1987 National Appliance Energy Conservation Act authorized the Department of Energy to set minimum efficiency standards for space conditioning equipment and other appliances each year, based on what is "technologically feasible and economically justified". Beyond these minimum standards, the Environmental Protection Agency awards the Energy Star designation to appliances that exceed industry efficiency averages by an EPA-specified percentage.

Despite technological improvements, many American lifestyle changes have put higher demands on heating and cooling resources. The average size of homes built in the United States has increased significantly, from 1500 ft² in 1970 to 2300 ft² in 2005. The single-person household has become more common, as has central air conditioning: 23% of households had central air conditioning in 1978, that figure rose to 55% by 2001.

As a cheaper alternative to the purchase of a new furnace or air conditioner, most public utilities encourage smaller changes the consumer can make to lessen space conditioning usage. Weatherization is frequently subsidized by utilities or state/federal tax credits, as are programmable thermostats. Consumers have also been urged to adopt a wider indoor temperature range (e.g. 65 °F in winter, 80 °F in summer).

Home energy consumption averages[3]:

  • space conditioning, 44%
  • water heating, 13%
  • lighting, 12%
  • refrigeration, 8%
  • home electronics, 6%
  • laundry appliances, 5%
  • kitchen appliances, 4%
  • other uses, 8%

Energy usage in some homes may vary widely from these averages. For example, milder regions such as the southern U.S. and Pacific coast of the USA need far less energy for space conditioning than New York City or London. In milder climates, lighting energy may easily consume up to 40% of total energy. Certain appliances such as a waterbed, hot tub, or pre-1990 refrigerator use significant amounts of electricity. In most residences no single appliance dominates, and any conservation efforts must be directed to numerous areas in order to achieve substantial energy savings. However, Ground Source Heat Pump systems are the more energy efficient, environmentally clean, and cost-effective space conditioning systems available (Environmental Protection Agency), and can achieve reductions in energy consumptions of up to 70%.

Best building practises

Current best practises in building design and construction result in homes that are profoundly more energy conserving than average new homes. See Passive house, Superinsulation, Self-sufficient homes, Earthship, Straw-bale construction

Commercial Sector

The commercial sector consists of retail stores, offices (business and government), restaurants, schools and other workplaces. Energy in this sector has the same basic end uses as the residential sector, in slightly different proportions. Space conditioning is again the single biggest consumption area, but it represents only about 30% of the energy use of commercial buildings. Lighting, at 25%, plays a much larger role than it does in the residential sector. [4] Lighting is also generally the most wasteful component of commercial use. A number of case studies indicate that more efficient lighting and elimination of over-illumination can reduce lighting energy by approximately fifty percent in many commercial buildings.

Commercial buildings can greatly increase energy efficiency by thoughtful design, with today's building stock being very poor examples of the potential of systematic (not expensive) energy efficient design (Steffy, 1997). Commercial buildings often have professional management, allowing centralized control and coordination of energy conservation efforts. As a result, fluorescent lighting (about four times as efficient as incandescent) is the standard for most commercial space, although it produces certain adverse health effects. As most buildings have consistent hours of operation, programmed thermostats and lighting controls are common. However, too many companies believe that merely having a computer controlled Building automation system guarantees energy efficiency. As an example one large company in Northern California boasted that it was confident its state of the art system had optimized space heating. A more careful analysis by Lumina Technologies showed the system had been given programming instructions to maintain constant 24 hour temperatures in the entire building complex. This instruction caused the injection of nighttime heat into vacant buildings when the daytime summer temperatures would often exceed 90 degrees Fahrenheit. This mis-programming was costing the company over $130,000 per year in wasted energy(Lumina Technologies, 1997). Many corporations and governments also require the Energy Star rating for any new equipment purchased for their buildings.

Solar heat loading through standard window designs usually leads to high demand for air conditioning in summer months. An example of building design overcoming this excessive heat loading is the Dakin Building in Brisbane, California, where fenestration was designed to achieve an angle with respect to sun incidence to allow maximum reflection of solar heat; this design also assisted in reducing interior over-illumination to enhance worker efficiency and comfort.

Industrial sector

The industrial sector represents all production and processing of goods, including manufacturing, construction, farming and mining. Increasing costs have forced energy-intensive industries to make substantial efficiency improvements in the past 30 years. For example, the energy used to produce steel and paper products has been cut 40% in that time frame, while petroleum/aluminum refining and cement production have reduced their usage by about 25%. These reductions are largely the result of recycling waste material and the use of cogeneration equipment for electricity and heating.

Unlike the other sectors, total energy use in the industrial sector has declined in the last decade. While this is partly due to conservation efforts, it's also a reflection of the growing trend for U.S. companies to move manufacturing operations offshore.

Issues with Energy Conservation

Critics of some forms of energy conservation make the following arguments:

  • Confusion of financial payback versus energy savings. For example, a consumer purchasing a new hybrid vehicle may focus on the improvement in the miles per gallon rating of the hybrid over a current vehicle, without taking into account the money put into manufacturing the vehicle. The hybrid car may give 45 mpg, saving the average driver 278 gallons per year. The hybrid engine cost $3000 extra, so with gasoline at $2.50 per gallon, it pays for itself in 4.3 years. This is a payback argument and neglects the important information that over 1000 gallons of gasoline have been saved in the payback period, regardless of costs. It also neglects the fact that resale value of a fuel efficient vehicle will be higher than a conventional gas powered vehicle. On the other hand, it also neglects the relative energy costs of the vehicles.
  • Relative to more suitable design of building lighting. Some critics suggest that it is inefficient to reduce lighting intensity levels in the workplace. The facts are that health studies have demonstrated that headache, stress (medicine), blood pressure, fatigue and worker error all generally increase with the common over-illumination present in many workplace and retail settings (Davis, 2001), (Bain, 1997). However, it has been shown that natural daylighting increases productivity levels of workers, while reducing energy consumption.
  • Retailers argue they need bright lighting to stimulate purchasing. This is, in fact, often true. The real issue here is a moral one. Does a given society value increased sales or decreased use of natural resources?

Jevons paradox

The Jevons paradox is an observation made by William Stanley Jevons who stated that as technological improvements increase the efficiency with which a resource is used, total consumption of that resource may increase, rather than decrease. It may also be that some conservation efforts have the same effect. For example, if 10% of a country's population reduces its use of gasoline by 10%, the price of gasoline may drop, and the remaining 90% of the population may use more gasoline as a result. However, this observation has not been sufficiently studied, and energy conservation is generally regarded as a beneficial undertaking. Compare Parkinson's law.

References

  1. ^ US Dept. of Energy, "Annual Energy Report" (July 2006), Energy Flow diagram
  2. ^ US Dept. of Energy, "Annual Energy Outlook" (February 2006), Table A2
  3. ^ US Dept. of Energy, "Buildings Energy Data Book" (August 2005), sec. 1.2.3
  4. ^ US Dept. of Energy, "Buildings Energy Data Book" (August 2005), sec. 1.3.3
  • Scott Davis, Dana K. Mirick, Richard G. Stevens (2001). "Night Shift Work, Light at Night, and Risk of Breast Cancer". Journal of the National Cancer Institute. 93 (20): 1557–1562.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • Bain, A., “The Hindenburg Disaster: A Compelling Theory of Probable Cause and Effect,” Procs. NatL Hydr. Assn. 8th Ann. Hydrogen Meeting, Alexandria, Va., March 11-13, pp 125-128 (1997}
  • Gary Steffy, Architectural Lighting Design, John Wiley and Sons (2001) ISBN 0471386383
  • Lumina Technologies, Analysis of energy consumption in a San Francisco Bay Area research office complex, for (confidential) owner, Santa Rosa, Ca. May 17, 1996

See also

File:Travancore 1940 energy conservation.jpg
An early attempt at energy conservation: This 1940 photo shows the chief minister of Travancore princely state in southern India test-riding a bus fuelled by charcoal gas. This innovation was expected to considerably reduce the consumption of petrol. Source.

Conservation education:

U.S. energy statistics:

International collaborative research:

UNEP- Energy Branch:

Commercial links:

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