For the physical concepts, see conservation of energy and energy efficiency.
Energy conservation is a process used to reduce the quantity of energy that is used for different purposes. This practice may result in increase of financial capital, environmental value, national and personal security, and human comfort.
Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote economic, political and environmental sustainability. Industrial and commercial users may want to increase efficiency and thus maximize profit.
On a larger scale, energy conservation is an important element of energy policy. In general, energy conservation reduces the energy consumption and energy demand per capita. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production.
By reducing emissions, energy conservation is an important method to prevent climate change. Energy conservation makes it easier to replace non-renewable resources with renewable energy. Energy conservation is often the most economical solution to energy shortages.
Energy efficiency trends in the United States[change | change source]
The U.S. is currently the largest consumer of energy, although at current levels of growth, it is possible that in the future China could become the leading energy consumer. 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 domestic consumers. Commercial and industrial energy usage are controlled by businesses. National energy policy has a significant effect on energy usage across all four sectors.
Transportation sector[change | change source]
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 subsidizedpublic 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 American and European workers have been replaced by workers in Asia 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).
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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".
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. Consumers have also been asked to adopt a wider indoor temperature range (e.g. 65 °F in the winter, 80 °F in the summer).
Home energy consumption averages:[change | change source]
- 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. 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 practices[change | change source]
Current best practices in building design and construction result in homes that are much more energy conserving than average new homes. See Passive house, Superinsulation, Self-sufficient homes, Zero_energy_building, Earthship, Straw-bale construction, MIT Design Advisor, Energy Conservation Code for Indian Commercial Buildings.
Smart ways to construct homes such that minimal resources are used to cooling and heating the house in summer and winter respectively can significantly reduce energy costs!
Commercial sector[change | change source]
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. 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.
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[change | change source]
The industrial sector represents all production and processing of goods, including manufacturing, construction, farming, water management andmining. 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.
The energy required for delivery and treatment of fresh water often constitutes a significant percentage of a region's electricity and natural gas usage (an estimated 20% of California's total energy use is water-related.) In light of this, some local governments have worked toward a more integrated approach to energy and water conservation efforts.
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.
The usage of telecommuting by major corporations is a significant opportunity to conserve energy, as many Americans now work in service jobs that enable them to work from home instead of commuting to work each day. 
Related pages[change | change source]
References[change | change source]
- ↑US Dept. of Energy, "Annual Energy Report" (July 2006), Energy Flow diagram
- ↑US Dept. of Energy, "Annual Energy Outlook" (February 2006), Table A2
- ↑US Dept. of Energy, "Buildings Energy Data Book" (August 2005), sec. 1.2.3
- ↑US Dept. of Energy, "Buildings Energy Data Book" (August 2005), sec. 1.3.3
- ↑California Energy Commission, "California's Water-Energy Relationship" (November 2005), p.8
- ↑Best Buy Optimas Award Winner for 2007
- 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 Institute93 (20): 1557-1562. http://jncicancerspectrum.oupjournals.org/cgi/content/full/jnci;93/20/1557?ijkey=e1472aefe9398c2c26bf8515391f5940acc05495.
- 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 0-471-38638-3
- Lumina Technologies, Analysis of energy consumption in a San Francisco Bay Area research office complex, for (confidential) owner, Santa Rosa, Ca. May 17, 1996
- GSA paves way for IT-based buildings 
Other websites[change | change source]
- Resources for homes
- Government and international websites
More than a dozen states have adopted ambitious goals to cut back on energy use. My home state, Maryland, has one of the most aggressive plans.
This spring, Gov. Martin O'Malley signed a law that calls for a 15 percent reduction in electric use, per capita, over the next seven years. If successful, Maryland will reduce greenhouse gas emissions and achieve a cleaner environment. These efforts also will reduce the state's need to build new power stations and transmission lines. While no one will be rewarded for making that 15 percent reduction, or punished for failing to meet it, it is an important effort.
To reach the goal, local utilities are being asked to come up with conservation plans. Public education plans will also be initiated to encourage the state's 5.6 million residents to cut down on electricity use in their homes.
I asked an energy-efficiency expert to come to my 100-year-old clapboard house in the Washington, D.C., suburbs and show me what I can do to cut back on my electricity use. Jennifer Thorne Amann from the American Council for an Energy Efficient Economy cheerfully took up the challenge. Here is what she found on a walk through my house:
Insulation And Cracks
A lot of energy goes out of the cracks around doors and windows and through poorly insulated walls and ceilings. Thorne Amann suggested that I use a stick of incense or a candle to look for wasteful drafts by following the whiff of smoke. She told me that for less than $20 I could buy sealants to stop those drafts and save on heating and cooling.
She also said that for $250 to $500 I could hire a contractor to attach a gizmo called a "blower door" to my front door. This device sucks air from the house and helps identify the big leaks.
Lights consume about 10 percent of the electricity in a typical home. I replaced a lot of my incandescent bulbs with compact fluorescents (CFLs). These energy-efficient bulbs use one-fourth the amount of electricity that incandescent bulbs use. But I also have about 10 fixtures that are on dimmers — and standard CFLs do not work there. Dimmable CFLs are $17 apiece at my local hardware store. These light fixtures are not used all that much in my house, so I may not recoup the cost of those bulbs. Thorne Amann said prices should come down, because a new federal law will eventually phase out incandescent bulbs. I'll wait.
My refrigerator is 11 years old. It seems like a good candidate for replacement, because refrigerators built after 2001 are in general 30 percent more efficient than older models. However, we ran the numbers and found that my old fridge was actually pretty good. I would save a bit in energy costs, but not enough to make up for the purchase price of a new fridge.
The old freezer in my basement was a different story. If I traded it in for a new model, I would save $100 a year in electric bills and reduce my household electricity use by 6 percent. To see these savings, however, I would have to spend $450 for a new freezer — a painful move in the short run but worth it in the long run.
Electronics often consume up to a quarter of a home's electricity. In particular, appliances such as televisions and cable boxes are always drawing energy. Since I do not have a television or cable box, I avoid these are expenses. However, upon visiting a neighbor's house, I found that an ordinary TV draws around 60 watts, even if it is turned off most of the time.
Also drawing "phantom power" is anything with a charger that stays plugged in – from cell phones to laptops. So Thorne Amann suggested that I unplug those "bricks" when they are not actually doing work. It is even worthwhile for me to unplug my electric toothbrush stand, which draws two watts of electricity. That may not sound like much, but it is more energy than the lights in my bathroom use.
Heating And Cooling
Heating and air conditioning units are typically the biggest home energy users. My system failed last fall. When I bought a new one, I spent a few extra thousand dollars to get the most efficient model on the market. That probably was not a sensible investment from the standpoint of strict dollars and cents, but I did it anyway to reduce my family's "carbon footprint." Thorne Amann said even with a new system, I could save energy by making sure the ducts were taped up tightly (not with standard "duct tape" but with specialized metallic sealing tape). I might also consider insulating my ducts to save energy.
My electric water heater turned out to be the bogeyman in my house. It consumes a shocking 35 percent of my home's electricity. (Thorne Amann figured out its consumption by researching my model's specifications, which is not easy for most people to figure out. This is one reason why it may be worthwhile to use the services of an expert.) I could buy a marginally more efficient electric heater, or I could save a lot of electricity — and carbon emissions — if I switched to natural gas. Thorne Amann told me I could save by switching to low-flow shower heads and washing my clothes in cold water.
Thorne Amann said my family and I could also change some everyday behaviors around the house to reduce electricity consumption. For example, we could hang our laundry out to dry instead of using the electric dryer. I could set our thermostat higher in the summer and lower in the winter. And I could remind the kids to turn off lights and computers when they are not using them.
The Bottom Line
I can make a difference with simple steps, such as installing low-flow shower heads and compact fluorescent light bulbs. But if I want to get to the Maryland goal of a 15 percent reduction, I will have to invest a few hundred dollars in a new freezer. I can go further, and even cut my electricity bill in half, by replacing my water heater. In four to six years, those investments will probably pay for themselves. The power bills will also remain low after that.
Tips for Reducing Your Home Energy Use
Here are a few specific ways you can drive down your home energy use, reducing both your monthly electricity bills and your environmental impact.
Unplug Cords: Unplug anything with a power "brick" (the box on the power cord) if you are not using it. This includes cords like cell phone chargers and laptop chargers. Bricks consume power even when your gizmo is not plugged into it. Televisions and similar devices also draw power when off, so unplug those if you do not use them often. Large televisions can consume as much electricity as a refrigerator.
Change Your Bulbs: Compact fluorescent light bulbs provide quick and easy savings. Over the past few years, the light quality has improved, but you may need to try a few brands before finding the one you like best.
Measure Your Use: Buy or borrow a watt meter. Using this inexpensive device, which can be purchased for as little as $20, is an easy way to figure out how much electricity your plug-in appliances are consuming. If you find that an appliance is hogging too much energy, it might be worthwhile to invest in a more energy-efficient model.
Look For The 'Energy Star' Logo: Shop for home appliances with the Energy Star logo, which means the product has met standards set by the Environmental Protection Agency and the U.S. Department of Energy. Appliances bearing this logo are more efficient than base models.
Consider Gas: Switching from an electric water heater to a gas water heater will conserve energy, generally leading to lower bills and less carbon dioxide in the environment.
Seal Your Ducts: Make sure your ducts are tightly sealed, since energy can be wasted out of cracks. Insulation on ductwork can also help.
Use Fans: Use ceiling fans instead of turning down the thermostat, and only turn the fans on when people are in the room.
Source: Jennifer Thorne Amann, co-author of "Consumer Guide to Home Energy Savings."