The International Residential Code (IRC) is a comprehensive, stand-alone residential code that creates minimum regulations for one- and two-family dwellings of three stories or less. It brings together all building, plumbing, mechanical, fuel gas, energy and electrical provisions for one- and two-family residences. The IRC also provides a prescriptive approach (i.e., a set of measures) and a performance approach (i.e., energy modeling) for determining compliance.
The International Energy Conservation Code (IECC) is a similar code which encourages energy conservation through efficiency in envelope design, mechanical systems, lighting systems and the use of new materials and techniques. The IECC is similar to the energy related components of the IRC, and is referenced within the IRC, though the two are not always identical. Each state has its own energy code requirements. State energy codes are often based on a version of MEC or IECC (e.g., the 1992 MEC, the 2001 IECC, etc.); though it is worth noting that a few states have no requirements or may only have an energy code as a recommended practice. Current state codes can be found at the Building Codes Assistance Project .