You've changed your light bulbs to CFL and LED bulbs and your electric bill still soars each month.

You might know that your 15-year-old refrigerator isn't helping matters, but replacing appliances is expensive.Is it worth the investment to replace aging appliances with more energy-efficient models?The U.S. Energy Department estimates that appliances account for about 13 percent of household energy costs, with refrigeration, cooking and laundry taking up the bulk of energy use.Water heaters account for an additional 18 percent, making appliances and water heaters a prime target for energy savings."People are interested in energy efficiency," said Linda Saltzer, co-owner of Saltzer's Appliances in Lehighton. "It's one of the first things people ask when they come in."A 2014 national survey conducted by the Consortium for Energy Efficiency found that 45 percent of households had purchased an Energy Star-labeled product in the past year.Is it worth upgradingappliances?In most cases, it's worth upgrading an appliance if it's more than 10-12 years old. Improvements in energy efficiency have increased substantially over the past decade and even the least energy-efficient appliance available today will use less power than a top-of-the-line appliance from 2000."Refrigeration is the biggest way to save," said Saltzer. "If someone has a 20-year-old refrigerator and buys a new energy-efficient refrigerator, they're going to see a huge difference."There are calculators available online to help you do the math. EnergyStar.com's "Refrigerator Retirement Savings Calculator" estimates that replacing an 18-cubic-foot refrigerator from 2000 could save $230 over five years.It's a substantial savings, and might come close to covering the cost of a new refrigerator over a life span of 10 years.What makes today's appliances more energy efficient? Big improvements in compressors and insulation were made to refrigeration designs around the turn of the millennium, and manufacturers have spent the past few years refining this technology.For example, some energy efficient refrigerators and freezers now have an "adaptive defrost" cycle, which monitors compressor activity and defrosts the unit only when necessary.Washers are using less water, resulting in less energy use to heat and pump water for each cycle. (If you pay for water, you'll also slash your water bill.)More efficient washers can sense the load size and use just the amount of water and soap necessary.New this year are more energy-efficient dryers. Whirlpool is the first to offer an Energy Star certified dryer, which uses advanced in-drum moisture monitors and an "EcoBoost" option that uses fewer heating elements and a longer drying cycle.The company estimates that this technology will save homeowners more than $1,700 in energy costs over the 12-year life span of a dryer, when compared to dryers just 10 years old.Changes to water heatersRecent changes to federal guidelines mean that it's easier to find a more efficient water heater for your home a big deal for the appliance that accounts for nearly one-fifth of your home's energy bill. If you're replacing a model sold before 2004, you're likely to see substantial savings."The U.S. Department of Energy is requiring all water heaters made after April 16, 2015, to be more efficient," said Natalie Turner, a representative from Lowe's."Because of this change nearly all models that are currently available for sale now provide consumers with higher efficiency and lower energy costs."She noted that the biggest savings will come from upgrading from an older water heater to a heater utilizing new technology, such as a heat pump water heater.Heat pump water heaters, sometimes called hybrid heaters, use a compressor to pull existing warmth in the air to reduce the amount of energy needed to heat water."According to Energy Star, certified heat pump water heaters can save a household of four approximately $330 per year on its electric bills compared to a standard electric water heater and over $3,500 over the heat water pump's lifetime," said Turner."While a certified heat pump water heater costs more upfront, the savings will pay back the difference in two years for a household of four."For example, the GE GeoSpring Heat Pump Water Heater available at Lowe's is 67 percent more efficient than a standard electric 50-gallon water heater."