Energy-efficient windows are judged on their performance according to a few different factors, including heat transfer, air leakage, light transference, and condensation resistance. If you're unsure whether a window is energy-efficient, look for an ENERGY STAR® label from the U.S. Environmental Protection Agency (EPA). If various products, including windows, meet energy-efficiency standards set by the federal government, the EPA issues this label to help consumers identify energy-efficient products.

A common way to modernize arched windows is to install interior window treatments that allow light through the curved portion up to and let you cover the bottom portion for privacy. You can also install plantation shutters to make an arched window look more modern. From the exterior, arched windows can appear outdated if they’re coupled with ornate trim, so toning down the decor can make your window look more natural with a modern design.

Replacement windows normally don’t come with new sills, as the sill is part of the window frame that the replacement window fits inside. If you’re replacing windows, it’s a good idea to replace the sill, as well, especially since the sill will be fully exposed and easily accessible for replacement.

Window screens can help keep some heat out of your home, which is one benefit of using them in summer. It’s also the reason experts suggest removing your screens in winter—so it’s easier for the sun’s warmth to filter into your home. This will keep you cozier and potentially reduce your heating bills.