National building codes govern residential and commercial construction requirements to protect against substandard living and working conditions. Energy codes are a subset of building codes, designed to promote energy efficiency in construction. There are 4 major energy codes in North America – ASHRAE 90.1, IECC, Title 24 Part 6, and NECB.
A majority of U.S. states and jurisdictions use the International Energy Conservation Code (IECC) model energy code as the basis for their local or state energy code, with most of the rest following the ASHRAE 90.1 Standard. Most jurisdictions simply adopt the IECC or 90.1 without modifications. ASHRAE 90.1 covers commercial buildings and residential structures 4-stories and higher. IECC and Title 24 Part 6 cover commercial buildings and all residential buildings.
Title 24 Part 6 is exclusive to California, while most provinces in Canada use the National Energy Code for Buildings (NECB) as the basis for their local energy code.
Codes are updated frequently – typically every 3 years – as new technologies, products, and strategies lead to greater opportunities for energy efficiency. According to the Department of Energy (DOE), a building designed to the minimum requirement of ASHRAE 90.1-2019 will be about 5% more energy efficient than one designed to 90.1-2016.