Because the performance path of the International Energy Conservation Code (IECC) is based on comparative performance analysis (Proposed Design as compared with the Standard Reference Design), computer simulation software modeling is required. With support of the U.S. Department of Energy through the National Renewable Energy Laboratory RESNET published “Procedures for Verification of International Energy Conservation Code Performance Path Calculation Tools”. The goal of the suite of software verification tests is to increase building code officials confidence in software tools that have been accredited by RESNET as meeting the procedures. The Procedures addressed the performance compliance path of the 2006 edition of the IECC. RESNET has revised the procedures to include the performance compliance path for the 2009 edition of the IECC. The revised publication is posted at RESNET Procedures for Verification of International Energy Conservation Code Performance Path Calculation Tools RESNET accredits software programs that follows the procedures and passes the suite of software tests to demonstrate the tool complies with the procedures. The list of accredited software programs are posted at National Registry of Accredited IECC Performance Verification Software Tools