We have a porch that is surrounded by the outside on three sides. On the one interior wall, it has a glass sliding patio door to our dining room. The exterior walls are largely lined by windows. The floor of the porch basically has a crawl space under it, not foundation. Even though the porch has windows rather than screens, it is not really winterized at all. Because it is not really at all insulated and it isn't heated, the temperature in the porch is always much closer to the outside temperature than the inside temperature. The porch is probably about 14 feet by 14 feet or so, and most of the area of the porch is taken up by our hot tub. (You could say that the only purpose of our porch is that it is the location of our hot tub.) It wouldn't be my objective to make the porch warm, per se, but I would like to insulate it so that it is at least much warmer than it is when the house is about 70 degrees warmer than outside. A warmer porch would reduce the amount of run time for the hot tub, saving electricity and extending the life of the hot tub components, and also keep the room from totally fogging up when we use the hot tub when it's cold. (The porch would receive some heat from heat loss through the dining room patio door as well as some from the hot tub.)
Anyway, is there any practical way to insulate a porch like ours? I really have no idea which features of the porch's exterior (roof, windows, glass door to the deck, floor) contribute the most to heat loss. I'm open to making realistic improvements to any part(s) of the porch but of course don't want to make an expensive improvement if it makes no difference. (For instance, no point in replacing windows if the floor has almost no insulating value, unless I can improve the floor as well.) I'm open to doing whatever work I can do myself or hiring someone if it's something beyond my skill level. It's possible that what I'm hoping to do isn't really possible or at least not worth it, but I hope to hear what you think. Thanks.