Do-it-yourself window sill insulation can improve energy efficiency and lower your energy bills by keeping out cold air in the winter and keeping the heat out in the summer. Your options to insulate a window sill include making inexpensive purchases at your local hardware store, using window treatments as decorative methods, making a window craft and replacing the window sill with frames that are more energy efficient.
The most inexpensive method of DIY window sill insulation is applying rubber weather sealing around the window's frame to help prevent drafts from coming in through any gaps. The only downfall of this sealing is that it can damage the paint around your window sill when the strip is removed.
Another inexpensive method is using window insulation kits purchased from hardware stores. Apply the shrink film contained in the kit to your window frames with tape, and use a blow dryer to shrink the film onto the window.
To insulate a window sill and enhance the look of the room choose layered curtains with heavy fabric that matches the room's decor Place the curtains over your windows to prevent drafts from seeping in. The closed drapes will keep out drafts, but won't allow for much light unless you open them.
You can also use cellular shades to block drafts from coming in your windows. These are custom fitted and allow light to come into the room, unlike the heavier drapes. To install them use a measuring tape to measure your window, and mark the bracket positions as well as the holes where the screws will be located at the top. Drill the pilot holes into the window frame, and attach the mounting brackets while making sure they are level. Insert a wood shim and clip your cellular shade into the brackets; then tighten the brace screws.
Another method to insulate a window sill is to make draft snakes to place in your windows. Sew fabric into the shape of a tube that is both large and long enough to fit your window sill, and use dried rice or heavy material to fill it.
If you choose to replace the entire window sill for better insulation use vinyl, fibreglass, wood or wood composites for the window frames and select spacers between double or triple glass panes that are made of foam, vinyl, steel or fibreglass. The spacers serve as barriers against heat loss and help to conserve energy.