Can the Color of Your House Reduce Your Energy Bill?

Objective

In this experiment you will investigate if the color of a structure affects the temperature inside the structure when in different environments.

Introduction

How does the color of your house affect the temperature inside of it? Consider this explanation by Jill Morton at ColorMatters.com:

"When summer comes to your Hemisphere, can color reduce the energy consumption in your home or business? Consider this: Would you be cooler wearing a light shirt or a dark shirt on a hot sunny day? If your science teacher or parents didn't convince you, the scientific fact is that white reflects the radiant energy rays of the sun and black absorbs them.
The same principle has a significant impact on a house. The hotter the roof, the hotter the rooms below. Light colored roofing and /or reflective coatings are like a white shirt for your house because they reflect radiant energy. Even a light gray hue is better than a blue or green." (Morton, 2006)

In this experiment you will test this idea by painting shoe boxes with light, medium, or dark colors to model painted houses. Then you will put the boxes in warm and cool environments and measure the temperature inside each box. Will color matter?

Terms, Concepts and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

surface temperature
indoor temperature
outdoor temperature
reflection
absorption

Questions

How different are the surface, indoor, and outdoor temperatures of a structure?
How do colors that reflect or absorb light affect the indoor temperature of a structure?
Which colors are best for saving energy in hot or cold climates?

Bibliography

This project idea was adapted from a science fair project by William S. in Mrs. Hannemann's 3rd grade class at Williams Elementary in Rockledge, Florida:
S., William, 2003. "Does the color of your house affect the temperature inside of it?" Williams Elementary, Rockledge, Florida. [accessed June 23, 2006]
http://www.energywhiz.com/3-5/SCIFAIR/2003WilliamS.htm
Morton, J. L., 2006. "Color and Energy Matters," ColorMatters.com [accessed June 23, 2006]
http://www.energywhiz.com/
This site has a java applet you can use to make printable, color graphs of your data:
NCES, 2006. "Create a Graph," National Center for Education Statistics (NCES) U. S. Dept. of Education. [accessed March 3, 2006] http://nces.ed.gov/nceskids/createagraph/

Materials and Equipment

3 shoe boxes
4 thermometers
heat lamp
large tray
ice
rock salt
plastic bag (preferably white)

Experimental Procedure

Collect 3 shoe boxes of the same size.
Paint one box white, one box gray, and one box black. Allow the paint to dry completely.
Put a thermometer in each box, place the boxes on a table and place another external thermometer on the table.
Record the "Starting Temperature" of each thermometer in a data table:
Box Color Starting Temperature (^oC) Room Temperature (^oC) Heated Temperature (^oC) Cooled Temperature (^oC)
none none
1 White
2 Gray
3 Black
Put the lids on the boxes and leave at room temperature for 30 minutes.
Take each lid off and quickly record the "Room Temperature" in the data table.
Put the lids back on and place a heat lamp above the boxes to simulate a warm, sunny day.
Arrange the boxes underneath the lamp so that they are all equally distant from the light source. This will be a control to be sure that one box is not getting more light or heat than another box because it is closer to the light source. Put the last thermometer in the center of the boxes to measure the external temperature of the environment.
Leave the boxes and the external thermometer under the heat lamp for 30 minutes.
Take each lid off and quickly record the "Heated Temperature" in the data table.
Were the temperatures the same or different? If the temperatures were different, which box heated up the most or the least?
Put the lids back on and keep the heat lamp above the boxes but add a tray of ice beneath the boxes to simulate a sunny winter day. Make the tray of ice by sprinkling a layer of ice with rock salt and covering with a white plastic bag to keep the boxes dry.
Arrange the boxes underneath the lamp on the ice tray so that they are all equally distant from the light source and put the thermometer in the center of the boxes.
Leave the boxes and the external thermometer on the ice tray under the heat lamp for 30 minutes.
Take each lid off and quickly record the "Cooled Temperature" in the data table.
Were the temperatures the same or different? If the temperatures were different, which box stayed warmest? Which box cooled off the most?
After you have recorded all the temperatures, make a graph of your data. You can make your graph by hand, or use a site like Create A Graph to make your graph on the computer.
Compare the results using your graph. Which colors worked the best to reduce temperature changes in which conditions?

Variations

What about colors other than black, white, and gray? You can make this project more difficult by increasing the number of colors you choose. Most major paint manufacturers can tell you the Light Reflectance Value (LRV) of any color paint chip. White reflects 80% of the light and black reflects 5%. You can conduct your test for a series of colors with different LRV values. Will the temperature increase or decrease with the LRV number of the paint color? Which colors should you choose for hot or cold climates? What about climates with four full seasons?
House color is only one aspect of house design. Does the material you choose on the outside of your house make a difference? In this experiment you used a painted shoe box, a paper product, to simulate a painted house. What about real materials used to cover houses? Try the experiment using different materials: adobe, stucco, wood, siding, metal, etc. Which materials are the coolest or the warmest? Use a light and dark colored version of each material. Do some materials have more extreme temperature differences than others? Which materials are the most stable against fluctuations? Which type of climate is suited best by each material?
Another way to save energy is to use insulation, a material that is placed inside the walls of a structure to keep the indoor temperature from fluctuating. Compare different materials used for insulating walls: fiberglass, paper. Try a similar experiment by wrapping the shoe box with each material. Which materials provide the most stable indoor environment? Look up the R-factor for each material. Does it correlate with your results?

Credits

Sara Agee, Ph.D., Science Buddies

This project idea was adapted from a science fair project by William S. in Mrs. Hannemann's 3rd grade class at Williams Elementary in Rockledge, Florida: S., William, 2003. "Does the color of your house affect the temperature inside of it?" Williams Elementary, Rockledge, Florida. [accessed June 23, 2006] http://www.energywhiz.com/3-5/SCIFAIR/2003WilliamS.htm