ADDITIONAL KNOWLEDGE :



Using & Saving Energy

Energy Use Basics

How We Use Energy

The United States is a highly developed and industrialized society. We use a lot of energy in our homes, in businesses, in industry, and for personal travel and transporting goods. There are four major sectors that consume energy at the point of end use.

• The industrial sector includes facilities and equipment used for manufacturing, agriculture, mining, and construction.


• The transportation sector comprises vehicles that transport people or goods, such as: cars, trucks, buses, motorcycles, trains, subways, aircraft, boats, barges, and even hot air balloons.


• The residential sector consists of homes and apartments.


• The commercial sector includes buildings such as offices, malls, stores, schools, hospitals, hotels, warehouses, restaurants, places of worship, and more.

Greenhouse Gases

Greenhouse Gases Basics

Many chemical compounds found in the Earth’s atmosphere act as "greenhouse gases." These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is reflected back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap its heat in the atmosphere.

Many gases have greenhouse properties. Some occur naturally. Some are also produced by human activities and others, like industrial gases, are only human-made.

What Are the Types of Greenhouse Gases?

Source: U.S. Environmental Protection Agency (Public Domain)

The major greenhouse gases the United States emits as a result of human activity and that are included in U.S. and international emissions estimates are:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Industrial Gases:
  • Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulfur hexafluoride (SF6)

There are other greenhouse gases that are not counted in U.S. or international greenhouse gas inventories:

• Water vapor is the most abundant greenhouse gas, but most scientists believe that water vapor produced directly by human activity contributes very little to the amount of water vapor in the atmosphere.
• Ozone is technically a greenhouse gas because it has an effect on global temperature. At higher elevations in the atmosphere (stratosphere), where it occurs naturally, it is needed to block harmful UV light. At lower elevations of the atmosphere (troposphere) it is harmful to human health and is a pollutant regulated independently of its warming effects.

In Homes

In Homes Basics

The ability to heat and cool is one important accomplishment of modern technology. Our ovens, freezers, and homes can be kept at any temperature we choose, a luxury that wasn't possible 100 years ago. But keeping our homes comfortable uses a lot of energy.

Lighting is also essential to a modern society. Lights have revolutionized the way we live, work, and play. Most homes still use the traditional incandescent bulbs invented by Thomas Edison. These bulbs convert only about 10% of the electricity they use into light; the other 90% is converted into heat. In 1879, the average bulb produced only 14 lumens (a measure of the quantity of light) per watt, compared to about 17 lumens per watt from modern incandescent bulbs. By adding halogen gases, the efficiency can be increased to 20 lumens per watt.

Compact fluorescent bulbs, or "CFLs," have made inroads into home lighting systems in the last few years. These bulbs last much longer and use much less energy than incandescent bulbs, producing significant savings over the life of the bulb.

Appliances such as refrigerators, washing machines, and dryers are also more energy efficient than they used to be. Congress passed the National Appliance Energy Conservation Act in 1990 that requires new appliances to meet strict energy efficiency standards. Learn what it means to be energy efficient.

Most of the energy used in homes is for space heating (41%), followed by electronics, lighting and other appliances (26%), water heating (20%), air conditioning (8%), and refrigeration (5%).

The number and variety of ways we use energy in homes is changing rapidly. Energy use for air conditioning has doubled since 1980. U.S. households currently plug in more appliances and electronics at home than ever before. While refrigerators and cooking equipment have long been standard in homes, the ownership of appliances such as microwaves, dishwashers, and clothes washers and dryers has increased over the past 30 years.

It is increasingly common for homes to use multiple televisions and computers. Additionally, the home electronics market is constantly innovating, and new products such as DVRs, game systems, and rechargeable electronic devices are becoming ever more integral to our modern lifestyle. As a result of these changes, appliances and electronics (including refrigerators) now account for nearly one-third of all energy used in homes.

Types of Energy Used In Homes

Natural gas is the most-consumed energy source in U.S. homes, followed by electricity, heating oil, and propane. Natural gas and heating oil (fuel oil) are used mainly for home/space heating. Space heating accounts for 41% of the energy used in U.S. homes. Electricity, which is used for heating and cooling, also lights our homes and runs almost all of our appliances including refrigerators, toasters, and computers. Many homes in rural areas use propane for heating, while others use it to fuel their barbecue grills.

Regional Consumption Data Reflect Population Shifts and Climate

In the late 1990s, homes in the South Census Region surpassed the Midwest in consuming the most energy in the United States. This shift reflects the economic boom in the region, which stimulated U.S. migration to the South and the construction of more and larger homes. In 2005, homes in the South consumed 3.26 quadrillion Btu, about 3% of the country's total energy use and about 30% of energy used in homes.

Due to the longer heating seasons, the Northeast and Midwest regions still consume the most energy per household, at 123 and 110 Million Btu per household in 2005, respectively.

Gains in Home Energy Efficiency Offset by More Electronics and Appliances

Total residential energy consumption has varied between 9.5 and 10.5 quadrillion Btu over the past 30 years. During the same period, U.S. population grew by 30% and there were 39 million new home starts, but consumption grew at a slower rate, due to improvements in building insulation and efficiencies of heating and cooling equipment, water heaters, refrigerators, and other major appliances. However, these efficiency gains were offset by increases in the number of homes with cooling equipment, clothes washers and dryers, and dishwashers. Additionally, a growing number of U.S. households now have multiple televisions, computers, and refrigerators.

Use of Consumer Electronics Increasing

While most home appliances have become more efficient over the past 30 years, the average U.S. household uses many more consumer electronics — in particular, personal computers, televisions and related devices.

In 1978, personal computers were expensive and not typically used by U.S. households. In 2009, 76% of U.S. homes had at least one computer, 8% more than just four years prior, and 35% had multiple computers. Also, most households had only one television in 1978. In 2009, the average household had 2.5 televisions. Over 45% of homes have at least one television with a screen size of 37 inches or larger. Screen size and average energy consumption per television have continued to grow over time.

DVD players and Digital Video Recorders (DVR), which did not exist 15 years ago, are now widespread. As of 2009, 79% of homes had a DVD player, and 43% had a DVR. Nearly a third of all households also had at least four electronic devices, such as cell phones, plugged in and charging at home.

Air-Conditioning Equipment Becomes Increasingly Common

The percentage of homes with central air-conditioning has more than doubled since 1980, with more than 60% of homes having a central system. All areas of the United States show a significant increase in air-conditioning equipment and use in recent years. Cooling now accounts for about 8% of total residential end use energy consumption in the United States, double its 1980 share. Except in the temperate climate regions along the West coast, air conditioners (AC) are now standard equipment in about 87% of U.S. homes.

Single Family Townhomes

Stock photography 

Energy Use in Different Types of Homes

About 80% of residential energy use is consumed in single-family homes, while 15% is consumed in apartments and 5% is consumed in mobile homes. These different home types, along with variation in home size, structure, climate, and vintage, contribute to the diversity in energy use in homes across the United States.

Single-Family Homes:

More than half of single-family homes use natural gas for space heating, while about one-quarter use electricity. Most single-family homes use three or more televisions and almost all single-family homes use a clothes washer and dryer.

In 2009, for main space heating equipment:

• 54% used natural gas
• 28% used electricity
• 6% used fuel oil
• 6% used propane/LPG
• Some houses don't use heat at all

For appliances and electronics:

• 96% used a clothes washer
• 94% used a clothes dryer
• 81% used a computer
• 67% used a dishwasher
• 53% used three or more televisions

Apartments

Natural gas and electricity are used for space heating in about the same number of apartments. About three-quarters of apartments use air conditioning equipment and more than one-third contain clothes washers and dryers.

In 2009, for main space heating equipment:

• 43% used electricity
• 42% used natural gas
• 6% used fuel oil
• Almost none used propane/LPG

Mobile Homes

Mobile homes are the most likely type of home to heat with propane/LPG. More than one-half of mobile homes use electricity and about one-fifth use natural gas for space heating. Unlike apartments, most mobile homes contain clothes washers and dryers.

In 2009, for main space heating equipment:

• 57% used electricity
• 20% used natural gas
• 12% used propane/LPG

Eighty-four percent of mobile homes have air conditioning (central system, wall/window units, or both).

For appliances and electronics:

• 90% used a clothes washer
• 83% used a clothes dryer
• 52% used a personal computer
• 36% used three or more televisions
• 33% used a dishwasher

In Commercial Buildings

Commercial buildings include a wide variety of building types — offices, hospitals, schools, police stations, places of worship, warehouses, hotels, and shopping malls. Different commercial activities all have unique energy needs but, as a whole, commercial buildings use more than half of their energy for heating and lighting.

Types of Energy Used in Commercial Buildings

Electricity and natural gas are the most common energy sources used in commercial buildings. Commercial buildings also use another source that you don’t usually find used in residential buildings — district energy. When there are many buildings close together, like on a college campus or in a big city, it is sometimes more efficient to have a central heating and cooling plant that distributes steam, hot water, or chilled water to all of the different buildings. This type of system (referred to as a district system) can reduce equipment and maintenance costs as well as save energy.

Energy Use by Type of Building

The types of buildings in the commercial sector are used for a mix of many different activities and uses. Retail and service buildings use the most total energy of all the commercial building types. This is not very surprising when you think about all the stores and service businesses there are all over the United States. Other commercial users of energy include offices, schools, health care and lodging facilities, food establishments, and many others.

Shares of Fuels Used by Commercial Buildings (2003)

Source: U.S. Energy Information Administration, 2003 Commercial Building Energy Consumption Survey (September 2008).

The top five energy-consuming building categories use about two-thirds of energy consumed by commercial buildings and include the following kinds of buildings:

• Retail and Service (20% of total energy consumed by commercial buildings)
  • Malls and stores
  • Car dealerships
  • Dry cleaners
  • Gas stations
• Office (17% of consumption)
  • Professional and government offices
  • Banks
• Education (13% of consumption)
  • Elementary, middle, and high school
  • Colleges
• Health Care (9% of consumption)
  • Hospitals
  • Medical offices
• Lodging (8% of consumption)
• Hotels
• Dormitories
• Nursing homes
• For Transportation

America is a Nation on the move. About 28% of the energy we use goes to transporting people and goods from one place to another.

Cars, vans, and buses are commonly used to carry people. Trucks, airplanes, and trains can be used to carry people and freight. Barges and pipelines only carry freight. In 2008, 1 there were about 250 million vehicles (cars, buses, and trucks) in the United States — more than three motor vehicles for every four people.

Automobiles, motorcycles, trucks, and buses traveled just over 3.0 trillion miles in the United States in 2008. That’s almost one-twelfth the distance to the nearest star beyond the solar system. It’s like driving to the sun and back 13,440 times.

Types of Energy Used for Transportation

Gasoline is used mainly by cars, motorcycles, and light trucks; diesel fuel is used mainly by heavier trucks, buses, and trains. Together, gasoline and diesel, and the biofuels ethanol and biodiesel that are added to gasoline and diesel, made up 83% of all the energy used for transportation in the U.S. in 2010.

There is currently a push to develop vehicles that run on blended fuels or fuels other than petroleum products. Today, there are some vehicles that run on electricity, natural gas, propane, and fuels with high concentrations of ethanol and biodiesel.

Hybrid-electric vehicles combine the benefits of gasoline engines and electric motors by reducing the amount of fuel required to move a vehicle. This is why hybrid-electric vehicles can get more miles per gallon of gasoline compared to vehicles that run on gasoline alone.

Energy Use By Type of Vehicle

Automobiles are the most common mode of transportation in the United States. Personal vehicles (like cars and light trucks) consume 60% of the total energy used for transportation, while commercial vehicles (like large trucks and construction vehicles), mass transit (like airplanes, trains, and buses), and pipelines account for the rest.

In Industry

The United States is a highly industrialized country. Industry accounts for about one-third of the energy used in the country.

There are many different uses and a variety of different energy sources used in the industrial sector. One main use is as boiler fuel, which means producing heat that is transferred to the boiler vessel to generate steam or hot water. Another use is as process heating, which is when energy is used directly to raise the temperature of products in the manufacturing process; examples are separating components of crude oil in petroleum refining, drying paint in automobile manufacturing, and cooking packaged foods.

Industry Uses Many Kinds of Energy Sources

"Other energy sources" account for 43% of the energy manufacturers' use of heat, power, and electricity generation. Among these sources are steam, pulping liquor from paper making, agricultural waste, tree wood, wood residues from mill processing, and wood-related and paper-related refuse.

In the manufacturing sector, the predominant energy sources are natural gas and electricity (a secondary source). Manufacturers also use several other energy sources for heat, power, and electricity generation that include:

• Steam
• Pulping liquor from paper making
• Agricultural waste
• Tree wood
• Wood residues from mill processing
• Wood-related and paper-related refuse

Energy Use by Type of Industry

Every industry uses energy, but there are a handful of energy-intensive industries that use the bulk of the energy consumed by the industrial sector.

The petroleum refining industry is the largest industrial consumer of energy, followed closely by the chemical industry. The refining, chemical, paper and metal industries together use:

• 97% of the energy feedstock
• 91% of the byproduct energy
• 67% of total inputs of energy for heat, power, and electricity generation

Energy Sources Used as Feedstocks

Many energy sources, such as coal and petroleum, are used in manufacturing not as fuel — but like ingredients in a recipe. When raw materials are used like this in the manufacturing process, they are called "feedstocks."

The share of each energy-related feedstock used by industry is:

• Liquefied petroleum gas (32%)
• Coal (6%)
• Natural gas (6%)
• Less common sources account for the largest share of feedstock (56%)

Saving Energy

We All Use Energy

All of us use energy every day — for transportation, cooking, heating and cooling rooms, manufacturing, lighting, and entertainment. The choices we make about how we use energy — turning machines off when we’re not using them or choosing to buy energy efficient appliances — impact our environment and our lives.

Efficiency and Conservation Are Different but Related

The terms energy conservation and energy efficiency have two distinct definitions. There are many things we can do to use less energy (conservation) and use it more wisely (efficiency).

Energy conservation is any behavior that results in the use of less energy. Turning the lights off when you leave the room and recycling aluminum cans are both ways of conserving energy.

Energy efficiency is the use of technology that requires less energy to perform the same function. A compact fluorescent light bulb that uses less energy than an incandescent bulb to produce the same amount of light is an example of energy efficiency. However, the decision to replace an incandescent light bulb with a compact fluorescent is an act of energy conservation.

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