HERS stands for Home Energy Rating System. The HERS Index is the standard used in the home efficiency industry by which a home’s energy efficiency is measured. It’s nationally recognized and allows homeowners to tell just by looking at a single number how energy efficient a home is. At TSI, we use the HERS Index to help explain to customers the improvements that can be made to their home in order to improve their score, but to also improve the home’s overall energy efficiency.