Conserving the amount of energy we use is often suggested as an important way people can combat things like acid rain and global warming. It is also an excellent way to combat the high cost of living. The use of Light Emitting Diode (LED) bulbs is often touted as one way to cut energy use. These bulbs are not the strip lights you have seen in school building and stores. LED bulbs are the size of a normal light bulb but have a type of covering over the bottom part of the bulb (see images below).

To find out the impact the choice of bulb has on the amount of electricity we use save this worksheet to your computer as a Word Document. The complete the following activity noting that you will post some of the data to the Question and Answer forum on the class web site by Friday of this week.:

Visit Wal-Mart, Lowes, or ACE and find both of the following:

1. A box of normal (incandescent) soft white light bulbs. These must be 60W, medium base, soft white bulbs. They may be general purpose or 2X (long life) bulbs. Make sure that they are general lighting bulbs and not 3 way, fan, or any other color bulbs.
2. A box of LED bulbs that are the equivalent of 60W. Make sure that they are general lighting bulbs and not 3 way, fan, or dimmable bulbs.

The LED bulbs will look like this: The normal light bulbs look like this:

You must find a LED that produces the equivalent light of a 60 watt normal incandescent bulb.

Note that the life of some bulbs is given as “year life”. For example 1.4 year life.
Each “year life” is equivalent to 3 hours per day for 365 days. 3 x 365 = 1095 hours. So, to convert “year life” into hours you will need to do the following: year life x 1095 = life of the bulb in hours.

A
Price of one 60 Watt normal incandescent light bulb (not the pack just one bulb!) . \$
B
Life time of the bulb in hours. Convert life in years to life in hours if needed. Ask me for help if you have not procrastinated hrs
C
Price of one LED bulb \$
D
Life time of the LED bulb in hours. Convert life in years to life in hours if needed. See me for help if you have not procrastinated hrs
E
How many normal bulbs would you have to buy to cover the life of one LED bulb?
F
The Total cost of all the normal bulbs calculated in E would be? \$
G
The total cost of the one LED was \$
H
Watts (electricity) used by the LED to produce equal light as the 60W normal bulb W
I
A 10 Watt bulb uses 5 more watts of electrical energy per hour than a 5 watt bulb. How much more energy does the normal bulb use per hour than the LED? W
J

``Multiply the extra energy used (answer to I) by the total life in hours for the LED. This will give you the amount of energy saved by using ONE LED bulb in your home.  Remember to show your work!``

W
K
Number of light bulbs in your home. Include all rooms, bathroom lights, lamps, fans, etc. but not strip lights. (Parents home)
L

Calculate the energy saved by changing all home light bulbs to LED’s (Make sure you show your calculations). Hint: You know how much energy is saved by one bulb –look at J.

W
M

``Electricity is sold in kW not W.  Convert the energy saved above from Wh to kWh (÷1000) ``

N

``The cost of electricity is about \$0.08 per kWh.  Calculate the cost of this saved electricity (answer to M).  This is how much money you would save, over the life of the bulbs, if you changed all of your bulbs to LED’s. Post this value to the Q&A forum by Friday  ``

O
Calculate the class average for the amount of money saved if only LED bulbs were used in the home.
P

``There are about 5,700 single family dwellings in Milledgeville. Changing all of the bulbs in Milledgeville to LED’s would save how much in electricity costs?    ``

Q

``There are about 18, 774 single family dwellings in Baldwin county. Changing all of the bulbs in our county to LED’s would save how much in electricity costs?    ``

Sample Solution