UV block determines whether or not your windows keep the sun's UV rays out of the house. Double-paned replacement windows allow light in, while blocking out the UV rays that damage your home's interior. UV rays can drastically fade your furniture and flooring. Old, single-pane windows run the risk of letting in UV rays, damaging your assets.

U-Factor measures the heat transfer through windows, indicating how well the window insulates your home. The measurement represents both heat gain during warm weather and heat loss during cold weather. The values range from 0.20 - 1.20. The lower the rating, the better the insulation.