The Performance Rating Method is the primary energy compliance approach in ASHRAE 90.1 Appendix G, comparing a building’s proposed design performance against the established baseline building standard. This method uses computer energy modeling to calculate annual energy consumption and demonstrate compliance. It enables buildings to exceed baseline requirements through various efficiency strategies and earn LEED certification credits.
Calculation Process
The Performance Rating Method requires building energy simulation software to model both Proposed and Baseline buildings using identical climate data and operational schedules. The baseline building incorporates ASHRAE 90.1 default equipment efficiencies, control strategies, and envelope specifications. The proposed building model reflects actual design choices. Annual energy consumption is calculated, with performance expressed as percentage improvement over baseline, typically ranging from 10-40 percent for sustainable designs.
Practical Applications
The Performance Rating Method allows design teams flexibility to exceed baseline standards through preferred efficiency measures. High-efficiency HVAC systems, renewable energy, superior insulation, or advanced controls can offset less efficient components. This approach rewards innovation and cost-effective solutions while maintaining consistent compliance standards. Building energy models generated for compliance also support operational optimization, utility rebate applications, and long-term performance verification.