When I got back to the boat to start the new season one of the projects I wanted to do was make the frig and freezer run better and more efficiently. In order to do this I place the pink fiberglass attic insulation on the outside of the two sides and the bottom of the unit. I did not do the top or other two sides because I could get them. The other thing I did was line the interior of the freezer with Reflectix foil insulation. It seems like this is aluminum foil on both sides of bubble wrap and I had my doubts.
Turns out I was totally wrong to doubt it. This stuff works great. I am using a lot less energy and the freezer is at least 10 degrees cooler. In fact I put two thermostats in the freezer. One is down inside the insulation and the other one is on top of the insulation, but still in the freezer. Would you believe the top one reads 45-50 degrees while the one on the other side of the insulation is 20-25 degrees.
I am so sold on this stuff I just ordered another roll and am going to try to do the same thing to the frig.