In old homes in Philadelphia, where I work, it is common to encounter mortise lock sets that are still going strong after 100 or more years. Recently we started working on a house from the 1700s with original interior door hardware that is still working. Installing building materials that will last is friendly to the environment and your wallet. Consider life-cycle costs. How much energy goes into making, packaging and shipping doorknobs that need to be replaced every 10 years?