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Energy Principle 6. The amount of energy used by human society depends on many factors.

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Teaching this principle is supported by 8 key concepts:


6.1 Conservation of energy has two very different meanings. There is the physical law of conservation of energy. This law says that the total amount of energy in the universe is constant. Conserving energy is also commonly used to mean the decreased use of societal energy resources. When speaking of people conserving energy, this second meaning is always intended.
6.2 One way to manage energy resources is through conservation. Conservation includes reducing wasteful energy use, using energy for a given purpose more efficiently, making strategic choices as to sources of energy, and reducing energy use altogether.

6.3 Human demand for energy is increasing. Population growth, industrialization, and socioeconomic development result in increased demand for energy. Societies have choices with regard to how they respond to this increase. Each of these choices has consequences.

6.4 Earth has limited energy resources. Increasing human energy consumption places stress on the natural processes that renew some energy resources and it depletes those that cannot be renewed.

6.5 Social and technological innovation affects the amount of energy used by human society. The amount of energy society uses per capita or in total can be decreased. Decreases can happen as a result of technological or social innovation and change. Decreased use of energy does not necessarily equate to decreased quality of life. In many cases it will be associated with increased quality of life in the form of increased economic and national security, reduced environmental risks, and monetary savings.

6.6 Behavior and design affect the amount of energy used by human society. There are actions individuals and society can take to conserve energy. These actions might come in the form of changes in behavior or in changes to the design of technology and infrastructure. Some of these actions have more impact than others.

6.7 Products and services carry with them embedded energy. The energy needed for the entire life cycle of a product or service is called the "embedded" or "embodied" energy. An accounting of the embedded energy in a product or service, along with knowledge of the source(s) of the energy, is essential when calculating the amount of energy used and in assessing impacts and consequences.


6.8 Amount of energy used can be calculated and monitored. An individual, organization, or government can monitor, measure, and control energy use in many ways. Understanding utility costs, knowing where consumer goods and food come from, and understanding energy efficiency as it relates to home, work, and transportation are essential to this process.

What does this principle mean?

This principle addresses the use of energy and factors that affect how much energy humans use. Demand for energy is increasing due to population growth and the development of poorer societies as they achieve a higher standard of living with greater industrial productivity. It is important to note that energy use is measured not just by electricity flow and gallons of gasoline used, but also in the "embedded energy" that is consumed by the production of the foods and products used by humans. Understanding the ways that energy use is embedded throughout our society is part of becoming energy literate.

The amount of energy we use is affected by several factors.


Why is this principle important?

This principle most directly addresses our consumption of energy, both on an individual level and on a societal scale. Building one's knowledge of energy consumption can prompt behavioral choices and motivate students to take personal action to reduce energy use. Activities that teach this principle are often designed to have a strong take-home message wherein the classroom learning extends to one's daily life and decisions.

What makes this principle challenging to teach?

Teaching this principle offers a means to address the misconception that reducing energy use equates to a lower standard of living. In fact, the opposite is true in many cases. A modern, efficient car can drive farther on the same amount fuel compared to an older car. Living nearer to school, work and community provides many conveniences while reducing the energy needed for transportation. Eating a vegetarian-based diet has many benefits for human health. Students participating in a 3-week energy conservation project (The Lifestyle Project) reported increased satisfaction and quality of life as a result of making reductions in their energy use (Kirk and Thomas, 2001. Educators will have to address the misconception that energy consumption (or even energy waste) is equated with socioeconomic success.

These concepts also present an opportunity to tackle common misconceptions about energy use.

  • Car idling: It is not necessary to warm up a car before driving in cold weather. It is more efficient to shut a car off at railroad crossings, the drive through and other short pauses in driving. Some new cars do this automatically.
  • Thermostat use: There is no need to raise the thermostat temperature during cold weather. With most home heating systems it is beneficial to lower the thermostat during the night or while away from home. (However, radiant floor heating systems are better left at a constant setting during day and night.)
  • All types of light bulbs should be turned off when not in use. It is a myth that it is more efficient to leave a light bulb on rather than switching it on and off.

Battling preconceptions is a constant challenge for educators. When trying to replace a myth with a fact, there are key steps that can ease this cognitive transition. The Myth Debunking Handbook provides clear guidance for educators. Examples of myth debunking techniques for common student preconceptions about climate topics were prepared by educators at a 2012 CLEAN workshop.

Issues of scale are important too. Students may place a disproportionate amount of emphasis on relatively small fractions of energy use. While it is a good practice to unplug cell phone chargers when not in use, it saves 16 times more energy to shorten your hot shower by one minute (see calculations below). Similarly, students may get the impression that switching to energy efficient light bulbs can "solve" the energy problem. By keeping scale in mind, students can appreciate the level of effort that is needed to significantly slow the growth in energy demand.
A cell phone charger, when simply plugged into the wall and not charging the phone uses a small amount of energy. The amount of energy varies from less than half a watt up to around 3 watts. For this example, let's say your cell phone charger draws 1 watt of electricity while sitting idle in the wall and is left plugged in for a full day.

(1 watt x 24 hours) = 24 watt-hours

24 watt-hours / 1000 = 0.024 kilowatt-hours

0.24 kilowatt-hours x 3412 BTU/kilowatt-hour = 82 BTU

Let's compare that to energy used while taking a hot shower. Shower flow rates can vary from 1 to 5 gallons per minute. We'll use an average of 3 gallons/minute.

3 gallons/minute x 444 BTU to heat one gallon of water = 1320 BTU per minute

1320 BTU per minute / 60 seconds = 22 BTU per second

82 BTU for the cell phone / 22 BTU per second for the shower = 3.7 seconds of hot shower to equal 24 hours of cell phone charger left plugged in.

Shortening your shower by one minute saves 1320 BTU, which is around 16 times the amount saved by unplugging the charger.

Take home message: unplug your charger and then skip the hot shower for one day, and you will have saved a significant amount of energy!

See related calculations by David MacKay, author of Sustainable Energy - Without the Hot Air



Related Pedagogic Methods:

CLEAN's Energy Awareness Quiz

Teaching this principle may evoke feelings of guilt from some students. Americans use more energy per capita than most other societies, while the consequences of our energy use affect vulnerable populations such as those living near coal mines or in areas that will be potentially inundated by sea level rise associated with carbon emissions. It is a delicate balance for educators to instill a sense of responsibility and empowerment in students' energy choices, while avoiding feelings of guilt or helplessness.

Similarly, issues of economic status may arise while teaching this issue. However, this can cut both ways. For example, a wealthy family may consume a lot of energy by driving large automobiles. Conversely, a wealthy family may also have the means to purchase an efficient car with modern energy saving technologies. Educators can be aware of unintentionally creating divide between students from different economic situations. Thankfully, saving energy saves money and can be done with little to no financial investment. So it is easy to find common ground on these issues.


Strategies for teaching this principle


These topics are experiential and there are many ways to teach them. A natural starting point is for students to consider their personal energy use. There are many activities, assignments and project ideas for this strategy.

It is especially helpful to include some quantitative analysis so that students can determine an absolute number for energy used or saved. This may help students understand the scale of energy use and may help resolve misconceptions. One caution is that measuring personal energy use could result in value judgments about wasting energy, or could point out differences in socioeconomic status of different students. Educators can be alert for these side-effects.

Middle school students can use devices such as the kill-a-watt to measure the electricity use from various appliances around their homes, such as with the activity Plugged into CO2.

High school students can take on a more comprehensive approach to quantifying energy use. In addition to measuring electricity use, students can examine their utility bills to consider heating, cooling and hot water use. Students can also calculate energy used by transportation by tracking mileage and fuel economy in their family cars using EPA fuel economy data. Lastly, students can do simple calculations to scale up measurements they have made. For example, they can calculate the energy savings if the entire class, school or community adopted simple energy-saving measures. Many of the college-level activities listed below are also suitable for a high school audience.

College students can take a quantitative approach to delve into some of the intricacies of energy. Beyond calculating their own energy use, they can consider the actual source of that energy and the resulting carbon emissions by using the EPA eGRID database. College students can also compare energy use between different societies and different times in history. This allows for a broader perspective on energy use and energy needs.


Example activities for a range of grade levels

Home Energy Quiz Students take a Home Energy Quiz from the Energy Star Program to identify home improvements that could make their homes more energy efficient. The resource includes follow-up information about energy-saving activities to reduce the cost of heating and cooling, supporting the student examination of energy use, energy efficiency and conservation. (middle school and high school)

Are You An Energy Efficient Consumer? Students examine how different countries and regions around the world use energy over time, as reflected in night light levels. They then track their own energy use, identify ways to reduce their individual energy consumption, and explore how community choices impact the carbon footprint. (middle school and high school)

Zero Energy Housing - Students investigate passive solar building design with a focus on heating. Insulation, window placement, thermal mass, surface colors, and site orientation are addressed in the background materials and design preparation. Students test their projects for thermal gains and losses during a simulated day and night then compare designs with other teams for suggestions for improvements. (middle school and high school)

The Big Energy Gamble - Students conduct a household energy audit and are specifically asked to understand the units of power and energy to determine the cost of running various household appliances. Finding the amount of carbon dioxide emitted for different types of energy and determining ways of reducing carbon dioxide output is the outcome of the lesson. (middle school through introductory college level)

The Lifestyle Project This multi-week project begins with a measurement of baseline consumptive behavior followed by three weeks of working to reduce the use of water, energy, high-impact foods, and other materials. The assignment uses an Excel spreadsheet that calculates direct energy and water use as well as indirect CO2 and water use associated with food consumption. After completing the project, students understand that they do indeed play a role in the big picture. They also learn that making small changes to their lifestyles is not difficult and they can easily reduce their personal impact on the environment. (middle school through college level)
After students have measured their personal or household energy use, educators can then make the bridge to energy consumption on the scale of communities, societies, nations or the globe. At this point, students can consider cultural, economic or social differences that affect energy use.
Energy Consumption Rates across the USA and the World - Students use Google Earth to analyze oil consumption per capita in the US and around the world. Students then use spreadsheets to create graphs and calculate statistics regarding per capita energy use among various categories. (high school through college level)

Gapminder: Unveiling the beauty of statistics for a fact based world view. In this interactive simulation, students can explore global CO2 emissions displayed by different continents/countries and plotted based on the GDP. A map view is also accessible. (high school through college level)


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References

US Energy Information Administration - EIA Statistics and Analysis - A wealth of in-depth data about energy production, use, prices and trends.

Energy Perspectives 1949–2011 - This is a graphical overview of energy history in the United States. The 42 graphs shown here reveal sweeping trends related to the Nation's production, consumption, and trade of energy from 1949 through 2011. From the Energy Information Administration.

Reducing Energy Use from the EPA, with information on energy efficiency, conservation, construction and green energy.

eGRID This EPA database is a comprehensive source of data on the environmental characteristics of almost all electric power generated in the United States. These environmental characteristics include air emissions for nitrogen oxides, sulfur dioxide, carbon dioxide, methane, and nitrous oxide; emissions rates; net generation; resource mix; and many other attributes.

Michael Bluejay's Guide to Saving Electricity ( This site may be offline. ) - This web site offers clearly-worded explanations about how electricity use works, how to measure electricity use and way to save energy.

Sustainable Energy - Without the Hot Air - by David MacKay. This book offers an easily-read guide to how energy is used in our society and what it would take to convert to purely sustainable forms of energy. The book uses a quantitative approach, yet is easy to follow and understand.

Kirk, K.B., and Thomas, J.J., The Lifestyle Project, Journal of Geoscience Education, v.51 no. 5, Nov. 2003, p. 496-499





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