It's easy for those dials to get knocked out of whack by oversized tubs of leftovers or marauding children or houseguests, so make sure you have the temperature set optimally in your appliances.
You should consult with your manufacturer, but in general the EPA recommends keeping refrigerators at 37 degrees F and freezers at 3 degrees. Anything colder is probably overkill, and a waste of energy.
That's important, because refrigerators and freezers use about a sixth of home electricity.
Not sure if the internal temps are actually correct? Place a weather thermometer inside to check the temperature and adjust the dials until you get the desired results.
Good news for those buying refrigerators and freezers shipped in 2014: they will be 25% more efficient than those sold today, if a newly proposed Department of Energy rule goes into effect as written.