G. Casey Cassidy
Activity 1
Some classrooms are over lighted. State standards recommend 50 foot/candles of illumination at desk height for classrooms. Even on gloomy days, the desks near the windows receive over 100 foot/candles from natural lighting. We will calculate the energy and dollars which could be saved if the lights along the windows were never turned on during the daytime.
Work with a partner to determine the following information and fill in the blanks.
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A. Number of bulbs to be kept off per room.
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B. Wattage of each bulb.
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C. Hours per day each bulb will be kept off.
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D. Days per year bulb will be kept off.
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E. Number of classrooms which can keep the same bulbs off.
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Check your numbers with the rest of the teams. Make any necessary changes above.
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F. Calculate the energy to be saved in one classroom by leaving these bulbs off.
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(A) x (B) x (C) x (D) = (F) Watt-hours/year
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Convert the Watt-hours to kilowatt-hours/year
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(F) 1000 = (G) kilowatt-hours/year
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Calculate how many dollars this action would save
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(G) x (cost/kwh) = saved per year
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Calculate the savings for all the classrooms
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(H) x (E) =
Determine if it is worth doing, you must compare the savings with the cost to do this action. Since it costs nothing to leave the bulbs off, it is certainly worth doing. How would you accomplish this action in your school?