EXPERIMENT 3:
HOW DO STORM WINDOWS WORK?
A pane of ordinary window glass is not a very good insulator. That’s why the many windows in your home may be letting a surprising quantity of heat “slip” through. Let’s suppose the outside temperature is a chilly 20oF, and that you keep your thermostat set at 70oF. If your home has 200 square feet of ordinary glass windows (a typical value), over 11,000 BTU’s of heat will pass through these windows every hour. Your heating system will burn three gallons of oil (or 400 cubic-feet of natural gas) every day to replace this lost heat!
Storm windows (or double-pane “insulated” windows) can cut this heat loss in half. Storm windows are installed over your regular windows — they trap an insulating layer of air between the two layers of glass.
This experiment demonstrates how storm windows work. Use the cardboard box from the previous experiments. Carefully cut four large “windows” in the sides of the box... the sketch on this page shows you where to put the windows. Now, tape a piece of plastic food wrap over each opening from the inside of the box. These pieces of plastic film represent ordinary single-pane windows. Use your cellophane tape, here.
