Not long ago, all refrigerators had to be defrosted manually. You would turn the refrigerator off, open the door(s), and allow any frost build-up to melt. When the frost had completely melted away, you would turn the refrigerator back on. Today, all but the smaller, apartment-sized refrigerators are self-defrosting. Self-defrosting means what it implies--though frost continues to accumulate inside the refrigerator, it melts automatically.

And this advance, although important, pales in comparison to current refrigerator technology. Refrigerators and freezers consume about one-sixth of all electricity used in American homes, and advances in technology have cut refrigerator energy consumption by 60% over the past twenty years.

There are a variety of current refrigeration products that could be considered as "smart." Some can tell you when it's time to change the water filter, while others can access the Internet and display news and recipes. Cool stuff, but still, the most important advance in refrigeration technology is in energy consumption.

And here's a great reason to trade in your old refrigerator - the electricity it uses is converted into waste heat and vented out the back or bottom of the appliance and into your kitchen. If a new refrigerator saves you 1,000 kilowatt/hours of electricity a year, you will cut your air-conditioning costs by approximately $34 a year!