Calculate kilowatt hrs
/Home power budget

Lesson 4

#4 of 6 TITLE: Calculating a kW-Hours  Home  Power Budget

SUMMARY:  Students learn how to make sense of their power meter, and correlate data they've observed from their power meter readings done in the previous lab curriculum activity .   They formulate a "power budget" showing what electrical appliances in the home are consuming energy.

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Instruction

  1. Have the students bring a power bill from their home showing how much kW hours were consumed by their home during a one month period. 

  2. Review the function of a home power meter.   Explain that it measures kilowatt Hours.  Explain that if a 100 Watt light bulb is left on for 10 hours, then it used 1 KWH which would cost  about $0.10

  3. Have the students conduct a one week or one month survey where they go out to their power meter and record the reading on the meter.  Also have them use a watch to record how fast the wheel is spinning.  Do this by having them count how many rotations occurred in a 60 second period. 

  4. As the students record their data, have them add their Watt hours to a table on the wall showing data for all students.  The table should have 1 column per day, one row per student.  Give the student a code number like "like house #1"  to get around the privacy issues.

  5. Make sure the each column has a daily total and then a $ amount under that, and then a lbs of CO2 below that.  One kW equals about 2 Lbs. of CO2. 

  6. Once the students start plotting their collective class carbon foot print they will suddenly be very aware of their wasteful habits in power consumption!  It's really a GREAT motivator!

  7. Have the students try and to an accounting  / bar chart / pie chart showing where they thought the total kW hours .  Tell them to use the power measurements they took in the previous lab experiment to make as accurate estimations as possible.