Drafts and other comfort problems: Old single-pane windows are the most likely to produce uncomfortable drafts, but even newer windows can develop air leaks and broken seals that result in home comfort problems.

High energy bills: Drafts aren’t the only result of leaky, inefficient windows. You’ll probably also notice your energy bills will go up if your windows are starting to fail.

Warped or rotted window frames: Wood windows are especially vulnerable to these problems, which are unsightly and can result in big air leaks, flooding, and sooner or later complete window disaster.

Difficulty opening or closing windows: Single and double hung windows often become tough to work as the years go by. The windows become unstable, or the foundation settles, causing the window to either become jammed or fall closed easily.

Condensation between the panes: If you have double pane windows, this problem indicates that the seal has broken and moisture has gotten between the panes. The window is now no more efficient than a single-pane window, so you should replace it.