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Energy conservation is the practice of decreasing the
quantity of energy used while achieving a similar
outcome of end use. This practice 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
Efficiency trends in the United States
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.
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.
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%.
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, 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.
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.
A vehicle's gas mileage normally decreases rapidly at speeds
above 55 miles per hour. A car or truck moving at 55 miles an hour
can get about 15 percent better fuel economy than the same car going
65 mph. According to the U.S. Department of Energy (DOE), as a rule
of thumb, each 5 mph you drive over 60 mph is similar to paying an
additional $0.21 per gallon for gas (at $3.00 per gallon).
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
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
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 ft in 1970 to 2300 ft 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. 65F in winter, 80F in summer).
Home energy consumption
- 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%.
Current best practices in building design
and construction result in homes that are profoundly more energy
conserving than average new homes.
Issues with energy
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
- 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?