Many people consider a HERS Index Score of 40 or less as a tipping point to net zero energy homes. In 2017, there were 2,099 homes that were HERS Rated and had a HERS Index Score of 40 or less. The breakdown of the number of homes with a HERS Index Score of 40 or less by housing type is: The breakdown of the number of homes with a HERS Index Score of 40 or less by state is: *Does not include homes rated in California through the California Title 24 Rating System The top six states with homes HERS rated in 2017 with HERS Index Scores of 40 or less are: