This is a real world and practical “green” project – nice work, and there’s a kit!
Refrigerators use more energy than any other appliance in a household. The US has over 200 million refrigerators running at this time. Our temperature controller combined with a chest freezer will out perform any energy star refrigerator by a factor of 2. Combined with a smaller chest freezer footprint this efficiency can be improved even further. In our case we switched from a upright energy star refrigerator to a chest freezer and reduced our refrigerator energy usage by a factor of 8.