I wouldn't do anything drastic at this point but I also wouldn't wait for a bill to do some minor tinkering like eliminating air flow through gaps by spraying some foam and the idea of insulation in bags that you can stuff into certain areas is a good idea as well. The key with this type of insulation is to eliminate air flow from inside of cabinet to outside. Also, you hit on a good point. A good cover is important BUT because people always think of hot air rising they don't see the value in insulating the bottom of the spa as well. If the bottom is open I would definitely look to insulate it.
Yup. I wouldn't go spraying 20 cans of Great Stuff foam from Home Depot in there and compeltey filling the cabinet before I knew what was what.
hey... any actuall R Value for that stuff? I know they say it's better than compressed fiberglass :-/ but then again, that's not saying much.
Other areas of concern would be any vents on the skirting shoudl be sealed *during winter*. If the spa has rounded corners there may be gaps there as well. Also the gap between the shell and skirt is also a known area for potential air leaks. Gasketing this area would be a good idea.
Wind is also a big issue and can rob a hot tub of its heat very quickly. Folks placing a tub in a windy area can realize savings (and comfort) by placing a wind barrier up. The lesson here is think twice about placement before pouring the pad.
