Observations and results
Was 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 explore
Color and Energy Matters from Color Matters
Color and Vision: Light Absorption, Reflection and Transmission from The Physics Classroom
Energy-Efficient Paints for Your Home? from TheInfoMine
Can the Color of Your House Reduce Your Energy Bill? from Science Buddies
This activity brought to you in partnership with Science Buddies
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3 Comments
Add CommentNice try. Too many other factors to really determine if color has a noticeable effect. Materials, location (both global and local), nearby flora, water, rocks, roads, winds, etc., etc. all can contribute to house temperature; but again, a great way to introduce and investigate a science question. Thanks.
Reply | Report Abuse | Link to thisI have seen this taught to students and taught something like this for years, and have considered it deeply while consulting for EnergyTeachers.org.
Reply | Report Abuse | Link to thisThere are many unwritten assumptions taken here, so this study should also include an explicit enumeration of them. One the students should consider is shading. If the house/shirt is completely unshaded, all stated in the article is true, but if it is shaded, then maybe black is better, depending on the temperature of surrounding objects in the shade.
Also, there are various blacks and whites with differing emissivities in infrared, which could be quite important for cooling.
In short, there are more interactions than just sun>body/house, and an activity should be open-ended so the "buddy" can explore more instead of just getting the rote (and in a few limited cases wrong, although usually right) answer that white is better.
Reply | Report Abuse | Link to thisBefore one does anything one has to consider the site. In some areas like Fla, etc, south, a white roof would be great, in others like Minnesota, not so much.
I live in Fla and only using 1'' of urethane foam and galvanized roofing only had a $30 electric bill last month. But I bought under an old oak forest and run both A/C and fans plus eff appliances. Though it does include charging my EV's too, my only transport.
I'm moving and juat 1kw of PV handles both my A/C and other needs on my 32' sailboat including it's motor power. Saving energy cam be both profitable and fun if you do it right.