It's becoming more common to buy major appliances online—roughly 10 percent of refrigerator sales now happen there, versus at a brick and mortar store, up from a blip 10 years ago. But for all the convenience of online appliance shopping, it's not always easy to compare energy consumption data for various models on a retailer's website. An amendment by the Federal Trade Commission to its Appliance Labeling Rule should change that by improving the availability of online energy information for consumers.

The changes require online sellers to post the familiar EnergyGuide or Lighting Facts labels (or an FTC-approved icon linking consumers to the label in question) alongside all products. In the past, retailers had to post the contents of these labels somewhere on their site, but the information could take any form, so it was easily lost on consumers. To help retailers download the labels, the new rule also requires manufacturers to post their EnergyGuide and Lighting Facts labels online.

Energy efficiency might not be your top concern when shopping for a new appliance, but it should be somewhere in the decision matrix. In our testing of clothes washers, dishwashers, and refrigerators, we routinely find wide variation in energy consumption levels, enough to save (or cost) you a few hundred bucks over the life of the unit. And so, with all other factors—performance, cost, style—being equal, efficiency could be what pushes you toward one appliance over another.