Teaching about energy use 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.
6.3 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.
Energy use is at the heart of many environmental issues
The amount of energy we use is affected by several factors.
- Energy use can be reduced by limiting wasteful practices, by eliminating unnecessary uses of energy, or by opting to use the most efficient form of energy available.
- Technological or social innovation can reduce energy consumption.
- Design of products, technology, or infrastructure can result in lower energy consumption.
- Knowledge of the amount of energy used for different processes can inform decisions about energy use.
Misconceptions about energy use are commonplace
A persistent misconception implies 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. That said, in developing nations, access to energy is directly linked to the standard of living. As with many misconceptions, there is an element of truth to this idea.
There are also many folkloric misconceptions about energy use that can be addressed when teaching about energy consumption.
- 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.
Quantitative skills can strengthen understanding of energy useStudents may place a disproportionate amount of emphasis on relatively small fractions of energy use. For example, 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.
(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!
Avoid Value Judgements
Related Pedagogic Methods:
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. Carpooling, turning down the heat, and using less hot water saves both money and energy. It is easy to find common ground on these issues.
Bringing these ideas into your classroom
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.
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 sources 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. Students can also look ahead and consider how best to meet the energy demands of our growing population.
Teaching materials from the CLEAN collection
- 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.
- Clarkson Energy Choices Board Game introduces the concepts of energy use in our lives and the real impact that personal choices can have on our energy consumption, energy bills, and fuel supply.
- The Solar House video segment shares how an entire home can be constructed using green energy sources (solar and geothermal energy). Video is narrated by young boy whose father is the chief engineer on the project.
- Global Warming Wheel Card is a hand-held tool that students construct to estimate their household's emissions of carbon dioxide. One side of the wheel illustrates how much carbon dioxide a household contributes to the atmosphere per year through activities. The other side shows how changes in behavior can reduce emissions.
- Carbon Footprint Calculator - This EPA carbon footprint calculator is set up for easy-to-use inputs for three sectors: home energy use, local transportation, and home waste generation.
- How Much Energy is on my Plate? leads students through a sequence of learning steps that highlight the embedded energy that is necessary to produce various types of food.
- Where does your energy come from? Analyzing your energy bill and From Grid to Home are two activities that allow students to trace their energy consumption and energy sources though the use of their family's utility bills.
- US Energy Production and Consumption - Students explore energy production and consumption by contrasting regional energy production in five different US regions.
- Energy Walkabout puts teams of students in small groups to evaluate energy use in their school and make recommendations for improved efficiency. Students create and use an energy audit tool to collect data and present recommendations to their class.
- The Big Energy Gamble uses a household energy audit to help students learn about units of power and energy and determine the cost of running various household appliances. The outcome of the lesson involves calculating the amount of carbon dioxide emitted for different types of energy and determining ways of reducing carbon dioxide output.
- The Lifestyle 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. While completing the project, students are often surprised to learn how large their energy use is. They also learn that they can easily reduce their personal impact on the environment. This activity can be modified for younger audiences.
- Electricity data browser allows students to create or view graphs, reports, and tables of electricity use and costs. From the US Energy Information Administration.
- 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.
- Power Metering Project focuses on applying analytic tools such as pie charts and bar graphs to gain a better understanding of practical energy use issues. It also provides experience with how different types of data collected affect the outcome of statistical visualization tools. Designed for an AP math class; applicable to college students as well.
Find activities and visuals for teaching this topic
US Energy Information Administration - EIA Statistics and Analysis - A wealth of in-depth data about energy production, use, prices and trends.
https://www.iea.org/publications/freepublications/publication/KeyWorld2016.pdf contains timely, clearly presented data on the supply, transformation and consumption of all major energy sources for the main regions of the world.
Global Energy Statistical Yearbook 2016 is an interactive, engaging display of worldwide data for energy production, consumption, sources, and CO2 emissions over time.
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 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.