I picked up a new small (5.3) cubic foot chest freezer a few months back and finally had a chance to run a dedicated outlet to it. I plugged it in and let it run overnight. It has 3" walls and 3" flip up top. I had a piece of 3" isoboard foam sitting around the size of the top lid and figured I would set it on top of the lid and see if I detect a temp difference between the top of the lid and the top of the foam. There definitely is a noticable difference. As the freezer isnt going to be opened very often I am going to wrap the sides with the same foam (left over from another project) and then rabbet in a top cover that will attached to the top lid. The compressor exhaust air out the side of the unit so the unit will not be completely wrapped. I dont plan on sealing it tight so the big issue will be if there are any condensation issues. Since the foam is free it will be interesting to see if the kwh drops. With this small size, a energy star unit was avaiable but it was special order and considerably more expensive for marginal reduction in energy usage.