Energy Sciences

Lesson 4: Energy Efficiency: Use Less, Save More

For the Warm-Up, each student in the class will view different videos from Dominion Virginia Power in their energy efficiency series. ^41,42 Students will write down notes and report out to the class.

Activity 1: Energy Efficiency: Use Less, Save More @ Home

Students will act as Energy Inspectors and conduct an energy audit of their home. First they will make a list of items used in their home or on the go that use electricity. They will gather information about usage such as what time during the day they use this item and how many times during the year is it used (seasonal, monthly, weekly, etc.). They will then use this information to evaluate the cost of usage. We will use the formula: C = WNHDP/1000, where W is the power in Watts consumed by a device, N is the number of devices in use, H is the number of hours per day the device is in use, D is the number of days in a year when the device is in use, P is the price of electrical service in dollars per kilowatt-hour ($0.0887), and C is the total cost in dollars per year for using the device. We divide by one thousand to convert Watts to kilowatts. For example, a washing machine has an average rating of 1150 W. Let's assume you only have one washer and you wash clothes every 2 weeks. A wash cycle lasts about 33 minutes and you usually have 3 loads: white, light and dark colors. This means the washer runs for approximately 1.65 hours. How much money does the washer cost in 1 year? The calculations show

Once students calculate this they can investigate if there are more cost efficient options and calculate how long it would take to get the money back if an investment is made in a more cost efficient option.

Activity 2: Energy Efficiency: Use Less, Save More on the Road

Given a table, students will model the following for 3 types of cars: rolling friction force as a function of velocity, gas used as a function of rolling friction force, constant speed drag force as a function of velocity, gas used as a function of constant speed drag force, and total gas used to overcome forces as a function of velocity. Then, they will calculate how much money can be saved by the reducing rolling friction force and constant speed drag force.

For homework, students will make a top ten list of ways they are able to conserve energy in their household and write a proposal to their caregivers. They will use research from the internet to support their proposal.

A possible extension could include student modeling acceleration/deceleration and use of gasoline; then, calculate how much money can be saved by accelerating/decelerating at a slower rate when merging into traffic on a highway or local road. Students can also calculate the amount of money a taxi driver can save by turning off their car instead of idling. Restarting your car takes the same amount of gas used in 0.2 seconds of idling. ⁴³ Students can research occupations in the field of residential and commercial energy efficiency on the Energy Efficiency and Renewable Energy (EERE) website. ⁴⁴