Dog won't sleep in the dog house

I had an Akita that hated being in the house. He had a big doghouse I built for him, and he would get in it to get out of the rain, but he preferred being outside. Now, a neighborhood cat comes to our house about every night to sleep on our porch. My wife put him some blankets in one of the various chairs he got in to help keep him warm, but he likes to lay in the chair up at the front end of the porch for some reason. I worry about him getting too cold, but he gets up every morning about daylight, stretches, gives himself a bath and then leaves and goes to work! I have to keep reminding myself that cats and dogs lived outside for millions of years by themselves before us humans domesticated them....but I still worry about it.