Things You'll Need
Heavy, clear plastic
Insulating windows from the outside can lower your energy bills through the winter months. Outside installation may perform better in certain situations. Small children or cats that enjoy the windowsill may create tears or holes in the plastic, which may need to be fixed or replaced more often. However, with the proper installation, outside window treatment will last throughout the winter months. You may decide to keep the installation intact through the summer as well to keep cooling costs at a minimum. Complete one window at a time.
Purchase the installation material. This includes an adhesive product that is safe to use outside, such as Self-Adhesive Labeling Tape or 3M Super Weather Strip Adhesive; heavy and durable clear plastic, such as a painter's drop cloth; and non-static wipes for cleaning computers or LCD screens.
Squirt the window completely with a cleaning agent. Use a damp cloth to wash the window. Dry the window fully before continuing.
Measure the window. Start at the top. Determine the height from the wood molding to the bottom molding. Make a note of the measurement. Obtain the length, measuring from the right molding to the left.
Lay the plastic on a flat surface--for example, a table or clean concrete. Use your measuring tape to obtain the plastic's proper height and length. Indicate the measurements with the permanent marker.
Cut the plastic evenly with the scissors. Use a ruler or a solid, straight object if you have trouble cutting a straight line.
Apply the weather adhesive to top of the molding. If you have a broad molding on your window, apply to the far back. The tape or other adhesive needs to be in a straight line.
Place the top edge of the plastic on the adhesive. Run your finger over the plastic to stick evenly.
Use the non-static wipes to rub the plastic tightly over the window. Start with the right side. Rub down the window in one solid motion. This will stretch the plastic for a tight fit.
Add adhesive to the right molding. Apply the right-side plastic to the adhesive. Rub your finger over the right-side plastic to stick.
Repeat Steps 1 to 4 for the left side and bottom of the window
Complete both sections to insulate the other outside windows.