Insulated or thermal curtains can help to keep your home cool in the summer and warm in the winter, reducing energy costs and increasing comfort. Thermal lining fabrics are a specialty item, but are available at most fabric retailers. In most cases, the thermal insulation also blocks light, making them especially practical in bedrooms. Sewing your own insulated curtains allows you to get the benefits of environmentally smart curtains with the look you want for your home.
Determine how large you would like your curtains. Choose windowsill- or floor-length curtains, measuring from the rod, and allow at least two to three times the width of the window, plus any additional curtain rod length, for most curtain styles. Add 8-inches for a bottom hem, plus 1-inch for a top hem.
Cut the outer curtain fabric to your desired dimensions. Cut the thermal lining fabric 3 inches narrower and 3 inches shorter than your outer fabric.
Hem the bottom edge of thermal lining, facing the softer side inward. Press, using a cool iron, a 1-inch hem into the lining fabric. Turn the 1-inch hem over again to double it, press and stitch.
Fold and press a 4-inch hem into the bottom edge of each outer curtain panel. Fold again, press and stitch.
Place the lining fabric, right sides together, on top of the outer curtain fabric. The outer fabric will be larger on all four sides than the lining to create a finished edge. Center the lining fabric, pin and sew along the top edge, working with the right sides of the fabric together. Repeat for the remaining sides, leaving the bottom hanging free. Press well, creating a folded edge in the outer decorator fabric on the top and both long sides of the curtain panel.
Clip curtain rings onto the upper edge of the lined thermal curtain. Place onto the curtain rod.