Lesson Energy Conservation:
Considering Sources, Cost and Impact

Learning Objectives

After this lesson, students should be able to:

• Define and describe renewable energy.
• Explain that energy in its various forms can affect everyday objects and is involved in everyday events.
• List several ways to conserve energy.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Worksheets and Attachments

Pre-Req Knowledge

Students should know the definition of energy and some of its various forms.

Introduction/Motivation

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 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). Refer to the activities Greenewables: Making Renewable Energy Poster Presentations and Design a Net-Zero Energy Classroom to have students explore the applications and variables of renewable energy through literacy and design examples. 

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 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 going by 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!

Driving Example

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 look 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 class of gas/electric hybrid vehicles are a step closer in finding this balance.  Purely electric vehicles utilizes electricity instead of gasoline or diesel to power the car.  It is also another step toward balancing performance and minimizing usage of resources.

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. Students can learn more about energy efficiency by acting as engineers with the Wasting Energy at Home activity; followed by the experimental Stop Heat from Escaping: Testing Insulation Materials activity.

U.S. Energy Graphs

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 and Concepts for Teachers

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, use the attached U.S. Energy Graphs, provided by the U.S. Department of Energy (https://www.eia.gov/kids/). The first graph illustrates the energy flow in the United States in 2018.  It shows production by resource and consumption by sector.  It also shows imports and exports.  The next graphs are of U.S. energy production by resource, in 2020 and then historically since 1973.  The last set of graphs show energy consumption by source and sector in 2019, historically and per capita 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, https://www.eia.gov/kids/.

Associated Activities

• Wasting Energy at Home - Students act as energy conservation engineers and identify the ways energy is conserved or wasted in their everyday lives.

  Watch this activity on YouTube

• Greenewables: Making Renewable Energy Poster Presentations - In this literacy activity, students form expert engineering teams working for a (fictional) alternative energy consulting firm. Teams produce poster presentations making a case for their specialty alternative energy technology.
• Design a Net-Zero Energy Classroom - Students create concept designs for net-zero energy classrooms on paper by pasting renewable energy and energy-efficiency items into and around classroom sketches. They learn how these items—solar panels, efficient lights, computers, energy meters—work together to create learning environments that produce as much energy as they use.

Lesson Closure

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.)

Vocabulary/Definitions

appliance: An instrument or device designed for household use, especially one operated by electricity.

energy: The ability to do work.

energy conservation: The wise and efficient use of energy resources, resulting in reduced energy usage.

fossil fuel: Nonrenewable energy sources, such as petroleum, coal, or natural gas, which are derived from living matter of a previous geologic time and used for fuel.

kilowatt hour : (kWh) A unit of energy. 1 kWh = the work done by a power of 1,000 watts operating for one hour.

nonrenewable energy: Energy from sources that are used faster than they can be created. Sources include oil [petroleum], natural gas, coal and uranium [nuclear].

regenerate: To re-grow or replace.

renewable energy: Energy that is made from sources that can be regenerated. Sources include solar, wind, geothermal, biomass, ocean and hydro (water).

therm: A unit of heat. (British thermal unit or BTU) For example, used to measure the amount of heat resulting from burning natural gas.

Assessment

Pre-Lesson Assessment

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:

• What are different types of energy?
• From where do we get energy?
• What does it cost us to get and use energy?

Post-Introduction Assessment

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 music; 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 do you think that our country could change from using nonrenewable to renewable energy?).

Lesson Extension Activities

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

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation (GK-12 grant no. DGE 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.