According to the U.S. Department of Energy, leaky and inefficient windows, skylights and doors account for up to 25 percent of the average household's energy bills. Some sources estimate as high as 40 percent. A lot depends on where you live:

WHAT TO LOOK FOR

The colder or hotter the climate, the greater your heating or cooling costs and the greater potential you have to save money on energy costs. Nearly everyone can benefit by replacing leaky, inefficient windows with modern energy-efficient windows. Depending on your location, you can cut energy costs by as much as 15 percent.

A Smart Investment in Arizona windows

Replacing all of a home's windows in Arizona can be a big investment. The good news is, it's an investment that can pay for itself in just a few years. Here's how:

• Improves curb appeal and increases resale value. According to the 2008/09 Cost vs. Value Report (a combined effort by Remodeling magazine and REALTOR® magazine), homeowners can expect to recoup about 93% percent for vinyl or wood window replacement.
• Reduces heating and/or cooling costs, which saves you money every year.
• Increases the comfort of your home.
• Can qualify you for rebates and tax incentives, like the Federal Energy Tax Credit, which provides up to $1,500 for any efficiency improvements made to your home in 2009 and 2010. (Save your sales order or NFRC label from the window and check for rebates and tax incentives in your area.)
  
  Learn more about the Federal Energy Tax Credit

To find out more about the many benefits of energy-efficient windows, visit the Efficient Windows Collaborative. The window selection tool on this site helps determine an approximate change in annual energy use given your home type, window type and geographic region.