It is important to review the submitted documentation and identify which code was used for the building. Next, to determine whether the building complies with that code, the path used to demonstrate compliance must be identified.
There are several compliance paths available in the 2009 and 2012 IECC and ASHRAE Standards 90.1-2007 and 90.1-2010. Each of these codes/standards contains a prescriptive path that clearly states specific requirements.
Prescriptive paths limit design freedom. Each of these codes/standards also has a performance-based path that provides more design freedom and can lead to innovative design, but involves more complex energy simulations and tradeoffs between systems. Residential and smaller commercial buildings with singular HVAC, service hot water, and lighting systems are more likely to be designed using a prescriptive approach. Larger commercial buildings that have multiple systems or varied uses and loads may find it more advantageous to follow a performance-based code. A topic brief has been prepared that discusses the various compliance paths in more detail (Resource 1).
BECP’s REScheck™ or COMcheck™ software may be used to demonstrate compliance if approved by the code official. Although Chapter 5 of the 2009 IECC and Chapter C4 of the 2012 IECC do not include specific mention of an envelope tradeoff, they do allow use of ASHRAE Standard 90.1-2007/2010, which has an envelope tradeoff. Therefore, the COMcheck software implements the envelope tradeoff even for the 2009/2012 IECC. COMcheck is thus not an exact implementation of the 2009/2012 IECC and is referred to as deemed-to-comply software for the IECC. COMcheck is also deemed to comply with ASHRAE Standard 90.1 because COMcheck does not fully implement the space-by-space envelope requirements in ASHRAE Standard 90.1. The REScheck software is a close implementation of the IECC, but is not specifically mentioned in the IECC and is therefore deemed to comply as well. Resources 2 and 3 illustrate which jurisdictions allow the use of COMcheck and REScheck on a state-by-state basis. It is also recommended to check with the jurisdiction having authority. For information on where to look on the REScheck and COMcheck report to identify the code and compliance path used, quick reference guides for code officials are available in the BECP Code Officials Resource Guide (Resource 4; see page 30 for REScheck and page 119 for COMcheck).
Some states and jurisdictions allow code compliance for residential buildings by way of the performance path using the Home Energy Rating System (HERS) scores. The HERS rating involves analysis of the home’s construction plans and at least one on-site inspection. This information is used to estimate the home’s annual energy costs and give the home an index between 0 and 100. The lower the score, the more efficient the home. The index is set up such that a home scoring 100 approximately complies with the 2006 IECC. A net zero energy home would score 0. Each reduction of one point equates to 1% reduction in estimated energy consumption. New Mexico is an example  of a state that allows HERS scores for residential code compliance.