Weatherproof dog doors come with either double flaps and/or other design features to make them more energy efficient. Energy efficient pet doors for windows are not easy to find, but we carry the best of them by Patio Pacific Pet Doors and Hale Pet Doors.
TIP: Be sure to consider the height of the drop outside your window. If it is too high for your dog you may need to put a ramp outside. If you think this applys to your situation see our large selection of Dog Ramps.