This document discusses the issues to consider when deciding whether to repair or replace historic wood windows. It outlines the advantages of repairing historic wood windows over replacing them with modern windows in terms of aesthetics, longevity, energy efficiency, environmental impact, and economics. Historic wood windows are more appropriate for older home styles, retain historic integrity, and are made from durable old-growth wood. Properly maintained historic wood windows can last over 75 years and be just as energy efficient as new windows. Replacing windows uses more resources and energy than repairing existing windows. From a cost perspective, repairing windows is more affordable over the long term.