R5 replacement windows are available from quite a few window manufacturers, while they do cost more initially, the payback will be greater as the years go on. Painted exteriors on windows with a 15 year guarantee on the finish is also another fairly recent innovation in the window industry. We feel that now is the time to invest in your future by saving more money now.  Additional comfort you will feel by eliminating hot and cold spots in your home AND excellent sound deadening from the outdoor elements are both added values that you get from R5 windows. You need to make sure the manufacturer is energy star approved and is listed on the Department of Energy’s NFRC website. Happy hunting for those energy saving windows that are going to pay you back over time.