The article discusses a new way to evaluate HVAC systems for energy efficiency. Instead of just looking at individual parts, this method considers the system as a whole. By comparing a building's heating and cooling needs to the energy used by the HVAC system, a more accurate efficiency rating can be determined. This approach has been incorporated into the 2018 Washington State Energy Code and has the potential to lead to a more performance-based evaluation of HVAC systems in the future.