You can add insulation to help with efficiency, but make sure you don't cover the condenser coils or cover the area of a skin condenser if the coils aren't readily visible. Find out where your refrigerator or freezer dissipates heat before you add extra insulation or you may reduce its efficiency.

Another way to improve the efficiency of chest freezers that many people are reporting success with is to stack foods within as close as possible and fill empty space with jugs of frozen water.