Shedding Light on Energy Efficient Bulbs

3.5 based on 22 ratings

Updated on Mar 19, 2013

Grade Level: 9th - 12th; Type: Physical Science, Engineering


This project will examine the actual cost of three household light bulbs by testing energy consumption.


Energy-efficiency is important to conserve power, our natural resources, and money. According to Energy Star, replacing just one light bulb with an Energy Star rated bulb in every household would save $600 million in yearly energy costs and prevent 9 billion pounds of greenhouse gas emissions. Compact fluorescent bulbs are said to consume up to 75% less energy than the traditional incandescent bulb. However, these bulbs contain mercury, a substance with known neurotoxic effects. In this study three bulbs will be examined for their energy consumption, cost, and environmental impact.

Research Questions

  • What is the actual cost per kWh hour for each bulb?
  • What is the actual electrical output compared to the manufacturer's label?
  • Which bulb performed the closest to its labeled energy value?
  • Which bulb gave off the most "pleasing" light?
  • Which bulb is the best value?

Terms to Know

  • Incandescent
  • Quartz-Halogen
  • AC Fluorescent
  • Compact Fluorescent
  • Voltage
  • Wattage
  • Lumens


  • Wattmeter
  • Lamp stand (e.g. table lamp, desk lamp)
  • Incandescent bulb
  • Compact Fluorescent bulb
  • Halogen bulb

Experimental Procedure

  1. Setup a chart with specifications of each bulb.

Hazardous Components

Life Span

Color Temperature (K, wavelength)

Lumens/Candle Power (Brightness)

Arc Length
Filament Type
Beam angle

Color rendering index (CRI)

Operating Temperature

  1. To test each bulb use the following set up:
    1. Light bulb in lamp - connect lamp cord to the wattmeter - connect wattmeter to the outlet.
    2. Leave the lamp on for 1 hour.
    3. Examine the light. Subjectively describe the light in terms of brightness and color.
    4. Record the following: kWh.
  2. Determine the actual cost per kWh for each bulb
    1. Actual bulb consumption (kWh) x cost per kWh = Actual cost per kWh of the bulb.
    2. Assuming the light is on for 5 hours a day, how much energy is consumed over a week? What is the total cost of operation?
  3. Discussion - If one bulb is the best value is it worth it in terms of health and the environment?


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