Article #157 - About Commercial Code Compliance

The three approaches to compliance can produce different results. Performance approaches require a higher degree of detail so that an individual building can be designed to meet the IECC requirements exactly. Prescriptive approaches tend to be somewhat conservative and use worst-case default assumptions so the prescriptive packages will apply to all buildings. Although the prescriptive approach may result in a more energy-efficient building because of its conservative assumptions, this situation is not always the case. The prescriptive approach does not generally account for many of the features that affect energy use, such as the effect window orientation and external shading have on solar heat gain. Trade-off approaches fall somewhere between the prescriptive and performance approaches in flexibility and complexity.

The different methods reflect the differing influence of engineers and code officials. For example, Chapter 7 of the IECC reflects the engineering viewpoint by covering all possible situations and systems in a building. Chapter 8, originally developed for simple buildings and later enhanced for more complicated ones, reflects the need of code officials for a simple, easy-to-enforce set of requirements.

The 1998, 2000, 2001, 2004, and 2006 IECC and the ASHRAE/IESNA Standard 90.1-1989/1999/2001/2004 contain requirements for all three approaches. If your state has adopted any of these codes directly, you may be allowed to use all three compliance approaches. Check with your local jurisdiction to determine which approaches and compliance tools you can use.

DOE provides a set of free COMcheck products that include paper-based prescriptive requirements and software-based trade-off requirements for the 1998, 2000, 2001, 2003, 2004, and 2006 IECC and ASHRAE/IESNA Standard 90.1-1989/1999/2001/2004. The ASHRAE Standard is used directly to demonstrate compliance with the prescriptive approach and includes the ENVSTD software to demonstrate the trade-off approach.

Since the early 1970s, ASHRAE has developed standards for commercial building energy use. Model code organizations have incorporated these standards into the Model Energy Code (MEC) and the IECC. The MEC codes were developed and maintained by the Council of American Building Officials (CABO). With the advent of the International Code Council (ICC), the task of maintaining the MEC codes was passed to the ICC and resulted in the release of the IECC codes. The first edition was released in 1998 and updated in 2000, 2001, 2003, 2004, and 2006.

The COMcheck software can be downloaded at no cost.

To learn more about the different compliance approaches, check out the article on the Three Approaches to Commercial Compliance.