Dust streaks or water stains around the window trim can be evidence of leakage.
While checking windows, some with missing locks and window lifts or counterbalance weights may be discovered. It also may be difficult to reach over the kitchen sink to open that window if it is the double-hung type. A window in the bathroom OVER the tub or toilet lets in uncomfortable drafts.
A special look should be taken @ the windows in childrens rooms. Are they high enough to be safe yet low enough to allow escape in the event of a fire?
Storm windows & Screens
Most windows transmit heat and cold far in excess of a typical house wall. Heat loss & transmission may be reduced by using storm windows often made in conjunction with screens. In cold weather, they save enough fuel to justify their expense & inconvenience, which vary with the house construction, climate & habits of the people in the house. Although the advantage of storm windows is that they reduce drafts, they are difficult to clean & are considered by many to be unattractive.
*Source: Crossett Real Estate Services
Vinyl thermo-pane window replacement is low maintenance/long economic life/easy to clean/visibly attractive/featuring safety locks and rust-free screening: also makes a statement as to the preventative maintenance & updating of the property. Make sure your Installer has properly installed your windows: incorrect installation may effect any warranties or guarantees extended by the manufacturers.*