Refrigerators have seen a huge bump in energy efficiency since 2000, according to Lifehacker.com. They now use 40 to 60 percent less energy than back then.

With fridges costing an average of $1,100, is it time to flip your fridge?

Here are some of the reasons you might want to consider and energy efficient refrigerator:

If you have a fridge more than 20 years old

In terms of maintenance for an older refrigerator, there isn't a lot that can be done to ensure the fridge lasts longer, nor would it be worth the price of trying to make it last a little longer. The best you can do is ensure that your current refrigerator is maintaining a temperature between 37 and 40 degrees. Make sure all foods and liquids are covered because uncovered foods release moisture, causing the compressor to kick on more often which uses more energy.

If your current refrigerator was built in the 1990s or earlier, then it's definitely worth buying a new one. You'll save between $100 and $200 a year in energy costs, according to EnergyStar. If it was made in the last 10 years, you're only looking at energy savings in the range of $5 to $20 a year.

If you're in the market for a new fridge

For energy efficiency, classic top-freezer refrigerators use less energy than side-by-side or french-door types.

According to EnergyStar, a top-freezer fridge costs $45 a year to run, a bottom-freezer refrigerator costs $70 a year and a side-by-side fridge costs $75 a year, so going with a top-freezer fridge will save substantially more compared to bottom-freezer or side-by-side fridges. Of course, the size of the refrigerator, its defrost type and whether the model has a through-the-door ice dispenser can lead to large variations in enerygy use.

An energy calculator is available at EnergyStar.

Which fridge type is the most energy efficient?

The most energy-efficient models aren't necessarily the most expensive, according to bankrate.com. Refrigerators that use the least energy can have relatively modest prices, partly because they're smaller and have fewer features.

The easiest way to compare is to read each model's black and yellow EnergyGuide label which includes a sliding scale that shows the appliance's estimated annual operating cost within the range of costs of similar models. EnergyStar provides this Product Guide for comparisons on annual energy savings.

Rebates and recycling programs by local utility companies and government tax incentives also can help lower the upfront cost of new energy-efficient appliances. Recycling your old fridge can prevent old refrigerant and foam from adding to carbon pollution, according to EnergyStar.