I insulated our backyard lanai and it is great. The previous homeowner truly just linked a lanai onto the back of the house. They laid down cement, put screened windows and a door on it and finished. It has no heating and cooling and isn’t easily airtight. I want to make the space lievable. Since the lanai is linked to the back of the house, I do have access to electricity. What I did was put down electric heated mats to be our heating system. I then laid a thin rug over top of them. For cooling I mounted a ductless A/C component to run in the summertime. I had to upgrade the windows with ones that had glass and made sure they were respectfully insulated. I needed a up-to-date door that didn’t let in air as well. It was quite overpriced doing all this work. I had to hire a supplier, electrician and a Heating and A/C supplier to get it laboring. Now I have a USble space. I set up a kitchen table and put some chairs around it. I have a good view of our lake and can truly eat and love it there. I have a stray animal that I was nervous about while I was in the Winter season. I added a animal flap to one of the windows. Now he can come in and kneel on the heated floor. I had a food and water bowl for him, a scratch post and a litter box. He hangs out in the lanai almost more than I do. I believe that was money well spent.