Residential windows generally have a lifespan of 15 to 20 years. However, factors like climate, quality of installation, and maintenance influence their durability. If you notice issues such as drafts, condensation between panes, difficulty in operation, or visible damage, it might be time for a replacement. Upgrading to energy-efficient windows can improve insulation and reduce utility costs. Regular inspection and assessment of your windows can help determine the right time for a replacement to maintain comfort, aesthetics, and efficiency in your home.