https://jsfiddle.net/wordlycra2/kstd8u47/ If you leave your cat's flap open, it can create a draft. This is a common issue that cat owners face. A draught excluder can help cut down the amount of cold air that enters the house. However an animal flap can provide greater protection against the elements. Tomsgates has a range of insulated cat flaps and dog doors suitable for any kind of installation, including wall-mounted installations. The Material One of the most important elements of the cat door is its insulation. It is the thing that keeps cold air out and warm inside. Insulation can be accomplished in various ways however the material from which the flap is constructed is the most crucial. A single flap will not make much difference in insulation But doors with dual or triple flaps are more efficient in insulation and stop cold air from entering the house. You can also buy draught-exclusion devices to wrap around the frame and reduce drafts. But, you must keep in mind that they will not prevent the cold air from getting in the room if your cat is attempting to use their door at the same simultaneously. Fill in the space left by your cat's flap using insulation such as styrofoam. This will stop cold air from entering your home, and also decreasing the amount of noise generated when your cat opens their pet door. It is worth noting that if you decide to do this, it is essential to measure the hole your cat's flap has made and select the filler material that is compatible with the material surrounding it. The RANGER pet door by Freedom Pet Pass is a great option for a high-quality cat flap. The door has a thick, insulated seal that reduces the loss of heat. It also has a sturdy magnetic seal that prevents cold air and wind from getting in through the flap. Its cellular PVC frames are 3,000X more insulating than the aluminum frames of inferior pet doors. Wind Resistance When a door for cats is opened, it creates a draft that means cold air can sneak into your home,