Lesson: Energy ConservationContributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Students should know the definition of energy and some of its various forms.
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Introduction/Motivation (Return to Contents)
Who remembers what energy is? Who can describe it for me? (Possible answers: The ability to do work, to make things happen, and to cause changes.) What are some different types of energy? (Possible answers: Electrical, light, chemical, thermal, mechanical, solar, sound, wind, hydro [water], nuclear, etc.)
Sources of energy can be put into two categories; nonrenewable energy and renewable energy. Nonrenewable energy is any type of energy that can be used up. In other words, sources of energy that are used faster than they can be created. Nonrenewable energy sources include oil [petroleum], natural gas, coal, and uranium [nuclear]. Renewable energy is any type of energy that is can be renewed in a short amount of time, or is being continually replenished or regenerated. These types of energy are not used as fast as they are created. Renewable energy sources include solar, wind, geothermal, biomass, ocean and hydro (water).
So, how much energy do we actually use? We use energy when we use lights, showers, cars or heat buildings, run appliances, or manufacture clothes and plastic toys. We also use energy when we exercise (jogging, aerobics), play sports or walk to class. Energy conservation is when we do something to reduce the amount of energy we use, such as turning off the lights, taking shorter showers, or riding a bike (instead of a car) to school. Conservation of energy helps to slow down the use non-renewable resources, such as the gas it takes to power a car. Do you think energy is expensive? How much does it cost to get energy? How much does it cost to use energy? We are going to look at the price of driving a car, using a light bulb and heating a home and figure this out!
How much does it cost to drive a car?
Does your family or someone you know drive a car to work? The average U.S. adult drives 15,000 miles (24,140 kilometers) per year and pays more than $2 per gallon of gas. Gas mileage is different for each type of car so how much you pay for fuel to drive your car may change a lot (see Table 1)! An example calculation for a sport utility vehicle (SUV): 19 mpg x $2 per gallon x 15,000 miles per year = $1,579 per year just to drive the car to work. Wow!
(For more information about vehicle gas mileage, refer to the U.S. Department of Energy's Fuel Economy website, http://www.fueleconomy.gov). Mechanical engineers who design cars are always looking for ways to balance the desire of car owners for larger and more powerful vehicles, while minimizing how much gas a car requires to operate. The new class of gas/electric hybrid vehicles may provide better balance.
Light Bulb Example
How much does it cost to light a light bulb?
All light bulbs are not the same. Have you noticed different types of light bulbs? Some are round. Some are spiral. Two types of light bulbs include incandescent light bulbs (the traditional light bulb) and compact fluorescent light bulbs (a light bulb that uses less energy). How do they work? While the same amount of light comes from a 100-watt incandescent light bulb as a 32-watt compact fluorescent light bulb (CFL), each requires different amounts of energy to work. Of the energy put out by an incandescent light bulb, 85% is in the form of heat, not light (that is why they are always hot to touch). Giving off unwanted heat is wasteful compared to fluorescent light bulbs, which give off less heat. This means that fluorescent light bulbs require less energy to give off the same amount of light as incandescent light bulbs. They also cost different amounts of money to use. For example, if your utility company charges $0.04 per Kilowatt hour (kWh), then it costs $4 to operate the incandescent light bulb for 1,000 hours ($0.04/kWh x 1000 kW/W x 100-watt bulb x 1,000 hours) and $1.28 to operate the CFL for 1,000 hours ($0.04/kWh x 1000 kW/W x 32-watt bulb x 1,000 hours). So, why don't we just use compact fluorescent light bulbs? Well, they initially cost more to manufacture and buy at the store.
Sometimes lighting accounts for more than 30% of a building's energy consumption. This is why engineers are always devising new building systems and illumination (lighting) technologies, such as compact fluorescent light bulbs, to decrease the energy use of buildings. Lighting engineers also examine window placements so that sunlight can be used to naturally light our schools, offices and homes instead of electricity and light bulbs.
Home Heating Example
How much does it cost to heat your home?
When it is cold outside, everyone must use some kind of energy to heat their homes. What type of energy heats your home? (Possible answers: Gas, electricity, oil, firewood.) A utility company sends you a bill to pay for the energy you use. (Bring in an example of your home energy bill or ask for example bills from your local utility company or for your school.) For example, the gas bill for a 2,500 square foot house might have a heating bill of $250 per month, which adds up to $3,000 per year! Could you reduce your heating bill by wearing a sweater?
Energy efficiency and building systems engineers work to help homeowners and businesses conserve energy and save money on the cost of heating and cooling buildings. They look around a building and make suggestions for changes that would decrease the amount of energy being used. Often, a change in the heating/cooling systems or lighting in a building can help conserve a lot of energy. For example, it conserves much energy if you do not heat, cool or illuminate a building when people are not using it, usually at night and during the weekends and holidays. Engineers also create appliances (such as washing machines and furnaces) that use less energy (increased efficiency), so as technology improves, replacing old appliances with newer ones often helps to conserve energy.
U.S. Energy Graphs
Using an overhead projector, show students the attached U.S. Energy Graphs to provide a larger context on historical energy consumption and production, a break down by type of energy produced, and historical per person consumption levels.
Lesson Background & Concepts for Teachers (Return to Contents)
Historically, U.S. consumers continually increase the amount of energy they use, especially electricity. Because of the decreasing amounts of nonrenewable fossil fuel resources, energy conservation has become a necessity. Engineers continually develop new technologies that are energy efficient and use alternative sources of energy for electricity production. Energy conservation does not mean "saving" energy, since energy cannot be created or destroyed. Conservation of energy really means how efficiently we use energy — how we can convert one form of energy into another without a large loss of usable energy.
This lesson is designed to help students understand where energy is wasted and where energy can be conserved. Later lessons examine specific types of renewable and nonrenewable energy sources in more depth.
For classroom overhead projector transparencies, use the attached U.S. Energy Graphs, provided by the U.S. Department of Energy (http://www.eia.doe.gov/). The first page of graphs illustrate the historical U.S. energy consumption and production, showing how energy use has increased, surpassing the overall amount of U.S. production. The second set of graphs shows the types of energy produced in the U.S. during the last 50 years, by source: coal, natural gas, crude oil, nuclear electric power, wood, hydroelectric power, natural gas plant liquids, solar and wind. Note that while the amount of renewable energy sources is increasing slowly, its total amount is no where near the huge amount of nonrenewable energy sources. The last graphs indicate per person energy consumption, and state by state. The U.S. Department of Energy website also provides an Energy Kid's Page with excellent information on renewable and nonrenewable energy sources, http://www.eia.doe.gov/kids/.
Vocabulary/Definitions (Return to Contents)
Associated Activities (Return to Contents)
Lesson Closure (Return to Contents)
What does it mean if energy is "renewable?" (Answer: Renewable energy can be re-used or is not used up.) What does mean if energy is "nonrenewable?" (Answer: Nonrenewable energy is used up faster than it is created. It will run out and be gone forever in that form.) What are some examples of renewable and nonrenewable energy sources? (Answers: Renewable energy sources include solar, wind, geothermal, biomass, hydro and ocean. Nonrenewable energy sources include oil [petroleum], natural gas, coal, and uranium [nuclear].)
Can you name one way that you could conserve energy in school or at home? (Possible answers: Turn off lights, wear warmer clothes and turn down the heat, carpool or bus to school.)
Attachments (Return to Contents)
Assessment (Return to Contents)
Brainstorming: As a class, have students engage in open discussion. Remind them that in brainstorming, no idea or suggestion is "silly." All ideas should be respectfully heard. Take an uncritical position, encourage wild ideas and discourage criticism of ideas. Have them raise their hands to respond. Write their ideas on the board. Ask the students:
Using Energy Game: Divide the class into three student teams. Select a member from one team to name one type of energy and the way s/he uses it. For example, Chris uses chemical energy from food to play kickball. Another student may use electricity from a nuclear power plant to listen to the radio; or use a light-sensitive photo-electric cell in a solar-powered calculator to convert sunlight directly into electricity to do her math homework; or use big, south-facing windows to heat a room; or use roof-top solar panels to heat swimming pool water. Continue this process for each team, making sure to select a new team member for each round. For each new idea, award that team one point. If a student is unable to come up with a new idea, the team does not get a point. If many team members are passing, have them identify a way they use energy and let their teammates help them determine the energy source. Play as long as you want.
Lesson Summary Assessment
Make It Real Discussion: Solicit, integrate and summarize student responses on the concepts taught in this lesson. Ask questions related to the vocabulary words (What does energy conservation mean?), confront the students with some topic issues (Why is solar energy a nonrenewable energy?), or solicit their opinions (How you think that our country could change from using nonrenewable to renewable energy?).
Lesson Extension Activities (Return to Contents)
Have the students calculate how much their family spends a year buying gasoline. A car's gas mileage (kpg or mpg) can usually be found in the owner's manual, by calling a dealer or looking on the Internet. Or, over the course of a few weeks, have students calculate a car's exact mileage by keeping track of the distance traveled and the gas purchased.
Have the students calculate how much money they spend to light one room in their house for a day. Have them survey how many light bulbs are in the room, the wattage of each bulb, and how many hours the light is on for the day. Provide an accurate local electricity cost per kWh for the students to use by calling your local utility company or looking at a monthly utility bill.
References (Return to Contents)
Dictionary.com. Lexico Publishing Group, LLC. Accessed September 21, 2005. (Source of vocabulary definitions, with some adaptation) http://www.dictionary.com
Dr. E's Energy Lab. Updated September 18, 2003. Energy Efficiency and Renewable Energy, U.S. Department of Energy. Accessed September 21, 2005. http://www.eere.energy.gov/kids/
Energy Kid's Page, U.S. Department of Energy. Accessed September 21, 2005. (Highly recommended for energy sources, renewable/nonrenewable energy information, energy uses, science of energy and saving energy) http://www.eia.doe.gov/kids/
Fuel Economy. Updated January 10, 2005. Energy Efficiency and Renewable Energy, U.S. Department of Energy and U.S. Environmental Protection Agency. Accessed September 21, 2005. (Resource to find and compare cars for gas mileage, greenhouse gas emissions, air pollution ratings and safety information) http://www.fueleconomy.gov
Power Kids: The Future of Energy. Online Customer Information Center, Milton Hydro, Ontario, Canada. Accessed September 21, 2005. (Practical information for kids on energy sources and conservation ideas) http://www.miltonhydro.com/kids.html
Waterman, Jim. BCN Environment Center. Boulder Community Network Environment Center. Accessed September 21, 2005. http://bcn.boulder.co.us/environment
ContributorsSharon D. Perez-Suarez, Natalie Mach, Malinda Schaefer Zarske, Denise W. Carlson
Copyright© 2005 by Regents of the University of Colorado
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.