However, check the seal around the glass. If there are air leaks, apply caulking around the outer edges where the glass fits in the frame. A clear silicone caulk is easy to apply and will probably look the best. All opening, or operable windows need weatherstripping because without it they are very susceptible to air leaks and heat loss. There are three major types of operable windows, plus jalousie style windows found in mobile homes.
Casement windows consist of a single sash, hinged at one side.
Most open to the outside and are operated with cranks or levers. Awning windows are similar to casement windows, but are generally hinged at the top. To weatherstrip casement or awning windows, open the sash as widely as possible and attach the weatherstripping material around the inside of the frame in such a way that it will be slightly compressed when the sash is in the closed position. The weatherstripping should be stretched tight before it is fixed in place to prevent wrinkles from forming, thus allowing air to infiltrate. Rolled vinyl with a metal backing is a good option for casement or awning windows, due to its durability and ease of installation.