Some years ago I installed a MaxSeal pet door into one of the French doors that leads into my home office. This lets Shadow & Gwen wander in and out over the course of the work day. I opted for their dual-flap model, which aims to be more weather-tight. We get heavy rain, and there’s no point in attempting to air condition the back yard.
In general, we’re very happy with the pet door. Where “we” are the two quadrupeds, who like their independence, and the bipeds who don’t want to be pestered about every possible coming or going.
If there’s one complaint I have about the dog door it’s the clatter it makes when it closes. Each flap has six metal clips that swing past magnets embedded in the aluminum frame. This acts as a brake for the flapping action, and holds it closed between ingress/egress events.