It actually feels better insulated than the human door itself.

I don’t usually review products, but I am so impressed with this door and the company that I wanted to say something about it. I have had this door for 6 years and it has taken a beating with 2 -100lb dogs busting back and forth through it like freight trains and other than normal replacement of the flap and seal a couple of times, I have never had any issues with weather, wind, other animals getting through etc. It is easy to clean, stands up to the worst weather. Never lets in cold air in the winter. It actually feels better insulated than the human door itself. I will never have another brand of dog door. Very, very impressed with this product and recommend it to all of my friends. The one time I have had to contact the company about where to purchase the hard top piece that holds the flap to the outside of the door, everyone was so nice and helpful. I was sent one free of charge within days. You guys do a great job!