HERS is a rating system for residential energy efficiency developed by EnergyStar and RESNET. Through a comprehensive design review and analysis, it incorporates HVAC, building enclosure and orientation, as well as appliance and lighting selection. A HERS score of 0 indicates a net zero-energy home, while a HERS score of 100 represents the energy consumption of home built to the 2003 IECC model energy code. A maximum HERS score of 70 is required for a home to be EnergyStar compliant.