Each state references or develops a building energy code using national energy codes such as ASHRAE 90.1 and the International Energy Conservation Code (IECC). To determine which code your state references, click on your state to read the residential and commercial energy code required. Once the code is identified, you may obtain the code from local authorities, purchase it online, or contact IECC and ASHRAE to purchase.
You can look up the energy code online. The Online Code Environment & Advocacy Network (OCEAN) is a great place to start.