When you think of the over 100 million fridges at the US, as well as a few hundred million fridges worldwide saving 1 to 10 pct of a refrigerators electricity represents numerous millions of fridges of energy savings.
My first thought was to have the fridge dial have an ecohappyface at the most effective
energy savings amount. Researchers have shown graphics affect human behavior, so turning the fridge to 7/10 energy use, as measured from actual human use, seems very likely with psychographics.
Then I thought, "hey, people likely have some unconscious natural dial direction preference where a slight majority turn it to the right, thus always placing the energy savings side on the autoprefferred (as measured) preference area could save energy"
There are some people that think fridges are about keeping food from spoiling. These people would value a thermochromic LCD where the color change phrase "food zone" or some better graphic, told them when their actual fridge, with its actual mass of food, at their particular building temperature was actually at the optimal temperature
Perhaps some combination of these three technologies from merely changing the fridge dial would bring the energy savings all the way to over 5 pct. Applied to china 5 pct is like 40 million fridges, which is a noticeable amount of energy.