Simple way to install this airtight dog door for your pet into your exterior door

[artstonez]

what about if you live in a state that's often colder than Antarctica in the winter, so you need to always have the inner door closed? And in the summer when it's 100 degrees and the humidity is 200 percent, you need the inner door closed for the air conditioning... I know I know move somewhere with better weather. but until then?