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Energy Consumption and Conservation

Program Area

This activity provides practice in operations with real numbers, in problem solving skills, and in critical thinking. It may be used in the Grade 9 Mathematics, Science, and Technology program, or in the Grade 10 advanced and general level mathematics courses as a supplement to any section on number manipulation skills, problem solving, or as enrichment material.

Learning Outcomes

  • Teaching, learning and evaluation will focus on the student's ability to:
  • Practice number skills and problem solving techniques;
  • Learn about charges for electrical energy;
  • Learn about the various ways to reduce electrical energy consumption and to compute the savings that can be realized through conservation measures;
  • Discuss other forms of energy used in homes and cities and to suggest other ways of conserving energy and reducing costs.

Classroom Development

  1. Use this unit as a supplement to problem solving or number skills.
  2. Consider allowing students to work in small groups to discuss where energy is used and needed in their homes and in the community, the cost of this energy, and ways to reduce consumption.
  3. To prepare students to do the exercises on the attached sheets, it may be necessary to teach or review the concept of kilowatt and kilowatt hour and to do some simple calculations of electrical energy charges.
  4. Students should do the questions on the attached pages. Working cooperatively in groups would be appropriate.
  5. Have the solutions presented by groups of students and use these solutions to encourage discussion of energy conservation, why it is necessary, and the benefits to society and to the individual.

Timing

Allow 2 periods (70 min)

Resources

This unit is based on material found in Energy Horizons: Energy Alert. Spring 1986.

Chuck Wilson
Education Coordinator
517 College street
Suite 406
Toronto, Ontario
M6G 4A2
(416) 323-9216
 
 
Student Activities

Energy Consumption and Conservation

 

Most people are aware of the need to reduce the amount of energy that they use in their homes. This conservation protects many of the natural resources that are used to produce energy and it also saves money.

 

  1. There are two 100 W (watt) light bulbs in the hallways of your house. These light bulbs are on for 6 h per day. The cost for electrical energy is $0.05 per kWh (kilowatt hour).
    (a) What is the annual cost to operate these light bulbs?
    (b) If both bulbs were replaced with 60 W bulbs, what would the annual cost be and how much money would you save?
    (c) If the bulbs were each replaced with 22 W fluorescent lights, what would be the annual cost and the amount of money saved?
    (d) Reducing the power consumption (wattage) and/or changing the type of bulb can result in reduced energy use and money saved. Are there any negative effects to this approach to energy conservation?

     

  2. Turning lights off when they are not needed is an effective way to reduce energy usage and save money. Suppose you have found that you can reduce your use of lighting in your home as described in the following table:
     Light Bulb (Watts)  Daily Reduced Usage (Hours)
    4 X 100W 2
    4 X 40W 3
    3 X 40W 4
    1 X 150W 1

    If the cost for electrical energy is $0.06 per kilowatt hour, how much money would you save over a 6 month period?

     

  3. Cities and towns need to consider ways to reduce energy consumption. One method is to switch to a more efficient type of lighting such as sodium lamps. It is known that one 150 W sodium lamp gives about the same amount of light as six 150 W incandescent lamps or two 175 W mercury lamps. Suppose that the main street of a town has 30 lamp posts each containing two 175 W mercury vapour lamps.
    (a) If you were a town councilor, what recommendations would you make to save energy and money for the town?
    (b) If your recommendations were followed, how much money would the town save each year? Assume that electrical energy costs $0.045 per kilowatt hour and use your own estimate of the number of hours that the lights will actually be used.

     

  4. A town has a street lighting system consisting of 30 lamp posts each containing two 150 W incandescent lamps. The town council has decided to reduce the number of lamp posts to 15 and to place one 150 W sodium light on each post.
    (a) Will the new lighting system provide more light, less light, or the same amount of light? Explain your answer.
    (b) If electrical energy costs $0.045 per kilowatt hour, and the street lights are on for an average of 10 h per day, calculate the annual cost for street lighting with the old system and with the new system. State the annual savings provided by the new system.
    (c) If it costs $10 000 to install the new system, how long would it take to recover this cost?

     

  5. What other things could a family or a town use to reduce the amount of electrical energy that they use?

     

  6. Most homes use kinds of energy other than electrical. Name some other kinds of energy used in your home and say how they are used. Also, suggest ways to reduce your consumption of these kinds of energy.