Can the Color of Your House Reduce Your Energy Footprint?
Key Concepts
Light, energy, heat, colors, absorption, reflectivity
IntroductionHave you ever wondered if changing the color of your house does anything other than alter its appearance? Could it also be doing something as practical as influencing how much money is spent on energy bills? On hot summer days, people consume a lot of energy to keep their houses cool. If less energy could be used to do this, not only would it save people money, it might also help the environment by decreasing the amount of energy we use! In this activity, you will test which colors may keep a house from getting quite as hot. Maybe you'll even find a good color to repaint your home!
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
BackgroundHow does the color of your house affect the temperature inside? To answer this question, think about the clothes that you would wear on a hot, sunny day. Would you rather wear a light-colored shirt or a dark one? You'd probably get much warmer in a dark shirt compared with a light one. This is because the lighter shirt reflects more light than the darker one, which absorbs much more light, or energy, warming up the shirt. It then transfers the heat to your body, warming you more than the light-colored shirt would. The house color works on the same principle.Materials
Preparation
Procedure
Extra: How does a house's color affect how warm it stays during the winter? You can investigate this by repeating this activity but this time test the boxes on top of a tray of ice (covered with a white plastic bag to keep the boxes dry). Which color box stays the warmest in winterlike conditions?
Extra: What about colors other than black, white and gray? To more closely mimic a real house you can repeat this activity, but instead of using construction paper, paint the boxes different colors. Most major paint manufacturers can tell you the light reflectance value (LRV) of any color paint. For example, white usually reflects 80 percent of the light that shines on it whereas for black it is 5 percent. Conduct your test for a series of colors with different LRV values. How does the temperature change with the paint color's LRV?
Extra: 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 activity you used a box wrapped in paper material to simulate a painted house. What about real materials used to cover houses? Try this activity again using different materials: adobe, stucco, wood, siding, metal, etcetera. Do some materials keep the house cooler than others in hot weather?
Observations and ResultsWas the black box the hottest and the white box the coolest, with the gray box somewhere in between in temperature?Just like keeping cool in a light-colored shirt on a hot day, the white box reflects more light than do the darker boxes. The white box should be the coolest inside, compared with the temperature in the shade nearby. The black box absorbs the most light, and this energy is transferred inside of the box over time and warms up the thermometer. The black box will probably be the hottest compared with the temperature in the shade. The gray box absorbs some light, so it will also be warmed up, but its temperature will be somewhere in between those of the black and white boxes. The reason that light-colored materials reflect more light than darker materials is actually rather complex but basically comes down to the number and type of chemical bonds in a material—these bonds affect what kind of light (specifically what wavelength) it absorbs. Some people and companies have also started adopting white roofs, which reflect much more heat than darker-colored roofs. More to ExploreColor and Energy Matters from Color Matters
CreditsTeisha Rowland, PhD, Science Buddies
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Key Concepts
Light, energy, heat, colors, absorption, reflectivity
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