Light bulbs are almost burnt out

Transcription

1 Light s are almost burnt out Incandescent Compact Fluorescent (CFL) Light Emitting Diodes (LED) The House of Representatives voted last year to withhold funding to enforce part of a 2007 law that increases efficiency standards for light s. The bill, signed into law in December 2007, provided these changes to U.S. energy policy. There should be roughly 25 percent greater efficiency for light s, phased in from 2012 through This effectively bans the manufacturing and importing of most current light s. Various specialty s, including appliance s, "rough service" s, colored lights, plant lights, and 3-way s, are exempt from these requirements as well as light s currently less than 40 watts or more than 150 watts. This exempts stage lighting. Stage lighting is generally thousands of watts, far more than any home installation. So the bill requires roughly 200 percent greater efficiency for light s, or similar energy savings, by Traditional s, which use essentially the same design invented by Thomas Alva Edison more than 130 years ago, use only about 10 percent of the energy they consume to produce light, according to the Congressional Research Service. The other 90 percent is wasted as excess heat. 1. If you lived in Minnesota where much of the year is cold and requires home heating, would you think that s that use energy to heat is such a bad idea? 2. How about if you lived in Florida?

2 2 Electricity is measured in kwh = kilowatts per hour of use. My 60-watt uses 60 watts in one hour. There are 1000 watts in a!"!"##$ kilowatt. If you want to figure out my s kwh, you would find out what decimal part of a kilowatt those 60 watts are = =.06 kwh!,!!!!"##$ People have been complaining about the expense of all of these new s. An costs about $1.00; a compact florescent costs about $5.00 and a light emitting diode might cost $ Who carries that kind of cash on them? That seems like a huge difference. But is it? Lets crunch the numbers and find out how much it might cost us. Complete the chart below. Kind of light Approximate kwh needed to operate this Cost for using this for one hour, given that electricity costs about $0.150 per kwh (rates will vary) Cost of using the for 5 hours per day Cost of using the for 5 hours per day for an entire year Initial cost of the Number of years that the is expected to last at 5 hours per day = life expectancy in hours hours per day days per year Cost of the per year = initial cost number of years of life Total yearly expense of that = cost of the per year + cost of the energy per year. 75 watt = 75 watts 1,000 watts = 0.075kWh $ hours 23 watt CFL with the equivalent lighting of a 75 watt light 9 watt LED equivalent to a 75 watt $5.00 $ hours = 25,000 hours = 3. Analyze your data in the table, in particular the last column. What do you notice? Reflect on the yearly cost of each. 4. I know that buying LED or CFL s will save me money on my bills, but I am not sure that they are worth it considering the s are so expensive. Help me better understand the cost over the next several years for just one. Graph the cost for me to use each type of for 10,000 hours. Remember to include the cost of new s if they run out (do not include the cost of the into the cost, add it in as an additional cost).

3 3 $140 $120 $100 Costs $80 $60 $40 $20 $0 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 Hours 5. According to your graph, for what hours of light usage is the the cheapest? For what hours of light usage is the CFL the cheapest? For what hours of light usage is the LED the cheapest? Should I be so worried about the high upfront cost of the LED and CFL s? 6. So far we have been looking at the cost of just one. How many light s do you think you have in your house (if you are not sure take a couple minutes to make an educated guess)? How much money will you lose or save per year by switching types? 7. The average house in the U.S. has about 40 light s. Consider the average cost per year for each type of. Graph the cost per year (the average cost including energy and the actual ) for 40 light s (assuming they are used for an average of four hours a day). Be sure to graph costs over at least ten years, if not longer. Hint: For this graph you will be including the cost of each in your graph.

4 4 By 2020, a second tier of restrictions would become effective, which requires all general-purpose s to produce at least 45 lumens per watt (similar to current CFLs). The phase-out of light s was supported by the Alliance to Save Energy, a coalition of light manufacturers, electric utilities and conservation groups. The group estimated that lighting accounts for 22% of total U.S. electricity usage, and that eliminating s completely would save $18 billion per year (equivalent to the output of 80 coal plants). 8. If 22% of the total yearly U.S. electricity usage costs $18 billion dollars, what is the total cost of electricity usage in the U.S.?

5 5 9. Here are some items that you might use in your every day life. Complete the table to see the approximate cost per year of each item. machine watts used per hour kwh cost per hour at $0.150 per kwh number of hours per day that you might use this item cost per year Most desktop Computer CPU (asleep/awake} Monitor (asleep/awake} 120 / 30 or less 150 / 30 or less Laptop computer 50 Flat Screen TV 120 Hair dryer Clothes dryer What did you learn? Do you have CFL or LED s in your home? What are the pros and cons of switching to these s? Should your home make the switch? Sources: Brought to you by: Yummymath.com