Description: You will be conducting a light bulb inventory and audit of your home.
First, you will be counting lightbulbs and calculating the amount of energy used for lighting your home daily. Next, you will calculate the cost of lighting your home each day. Finally, you can extend your calculations to determine the cost of daily lighting in all your classmates' homes. You will start in your own home.
Background: While taking a light bulb inventory of your home, be sure to examine the light bulbs. There may be lights in closets, under appliances, or in aquariums. You will need to determine the wattage of each bulb. (Note: This should be listed on the bulb itself. If not, use the figure of 34 watts for your calculations.)
The cost of electricity varies periodically. For the purposes of these audit forms $.07 was used to provide a means to compare dollars which can be saved through reduction in the amount of energy consumed.
Materials:
- Calculator
- Light meter (optional - available at Lowe's)
- Map or sketch of your home
A printable PDF version of the following steps is available below at the bottom of this page.
Procedure for Calculating the Light Usage in your Home
Step 1. Locate all the lights within your home. Mark each light and the number of light bulbs on a map of your home.
Step 2. Determine number of fluorescent bulbs in the home:
______________________ x _____________________ = _______________________
(# of bulbs per fixture) (# of fixtures) (# of bulbs)
Step 3. Determine the number of incandescent bulbs in the home:
_______________________ x _____________________= _______________________
(# of bulbs per fixture) (# of fixtures) (# of bulbs)
Step 4. Calculate watts per room:
_______________________ x ____________________ = _______________________
(# of bulbs per home) (Watts per bulb) (Total watts per home)
*You may have more than one line here. It depends on the types of light bulbs in your home. Be sure to list each of the different watts on separate lines.
Step 5. Calculate total watts per day per home:
_______________________ x _____________________ = _______________________
(Total watts per home) (Hours per day used) (Total watts-hours per day per home)
*Be sure to ask your parents if they turn on and off the lights each morning and evening. Try to calculate the average number of hours per day the lights are on.
Step 6. Convert watts to kilowatts:
________________ ÷ 1000 = _________________
(Total watts-hours) (Total kilowatts-hours)
Step 7. Calculate the cost of lighting your home each day:
________________ x $.07 = _________________
(Total Kilowatts-hours) (Total cost of lighting home each day)
Step 8. Calculate cost of lighting class' homes each day:
_______________________ + _____________________ = _______________________
(Add the cost of each students' home) (Total cost for lighting the class' homes)
Extensions:
- You have just estimated the number of light bulbs in each students' home. In small groups, and with the permission of your teacher and other teachers, conduct a light bulb inventory of each students' home in the school. As a class, compile the data on the estimated cost of lighting each students' home in the entire school.
Classroom Lighting PDF
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