EXPERIMENT 5:

LET THE SUN HELP HEAT YOUR HOUSE

THINGS YOU NEED: A cardboard box (an old shoe
box is fine). A“fish tank” thermometer (from Experiment 1). Some plastic food wrap (“Handi Wrap” or something similar). A roll of cellophane tape. An old piece of cloth.

Energy from the sun is free! That’s why it makes good sense to use as much of it as we can, as often as we can. How do we use the sun’s energy? By letting it stream through our windows.

To prove the point, build a cardboard “house.” Take your shoebox and tape a piece of plastic wrap across the open top. The plastic sheet should be smooth and wrinkle-free.

Next, punch a small hole in one end of the box, and slip the thermometer in place (as shown in the sketch).

Now, wait for a sunny day. Put the box on your sunniest window sill, with the plastic “front” facing the sun. . . and watch the thermometer. What do you think will happen? You are right! The temperature will climb as the sun’s rays heat the air inside the box.

OK, let’s repeat the experiment. But, this time, put your piece of cloth over the plastic “window” to simulate a window curtain or a shade. What do you think will happen now? Right again! The temperature will climb very slowly (or not at all!).

In the same way, the sun can help heat your home in winter. When the sun is shining, completely open curtains, raise shades and venetian blinds, and pull back draperies.

BUT, on a cloudy day (and at night, too), close curtains and draperies: they add insulation to windows and help reduce heat flow outside.