Appendix G is the section of ASHRAE 90.1 that establishes the Proposed Building Performance Method, the standard procedure for calculating building energy performance and demonstrating compliance with energy efficiency standards. This appendix defines requirements for energy simulation modeling, baseline building generation, and performance rating methodology. Appendix G governs energy compliance for most U.S. commercial buildings and is fundamental to LEED energy calculations.
Modeling Requirements
Appendix G requires whole-building energy simulation using approved software like EnergyPlus, DOE-2, or TRACE. The modeler must create both a Proposed Building model (showing actual design) and a Baseline Building model (using ASHRAE 90.1 default assumptions). Modeling must include hourly climate data, occupancy schedules, equipment loads, and HVAC system performance. HVAC equipment, controls, duct losses, and operation strategies must be specifically defined.
Compliance Verification
Appendix G calculations determine whether buildings meet code requirements and qualify for LEED energy points. The Proposed Building must achieve equal or better performance than the Baseline Building. Results are typically expressed as percent savings compared to baseline, with greater savings earning additional LEED points and utility rebates.