As a home rule state, mandatory building energy codes are adopted and enforced on a local level. As of September 2014, 28 communities in Colorado have adopted the 2012 IECC and 23% of all new construction activity in the state occurs in jurisdictions under the 2012 IECC. More importantly, almost 90% of the new construction in Colorado in 2013 was built at least to the 2009 IECC. Visit the website of the Colorado Department of Local Affairs for up-to-date jurisdictional adoption information.
In 2007, the Colorado General Assembly adopted two bills, both signed into law by Governor Bill Ritter, that impact the built environment in Colorado. House Bill 07-1146 requires all cities and counties with building codes to adopt and enforce a relatively up-to-date building energy code, referencing specifically the 2003 IECC. House Bill 07-1146 also authorizes to the Department of Local Affairs to provide grants to cities, counties, and non-profit organizations for training and technical assistance related to building energy codes and new construction that exceeds minimum energy code requirements.
Senate Bill 07-051 requires state agencies or departments embarking upon a substantial renovation, design, or construction of a state-assisted facility of more than 5,000 square feet to pursue U.S. Green Building Council LEED Gold certification, as long as construction costs can be recouped from decreased operational costs within 15 years.
The cities of Boulder, Fort Collins and Telluride and the counties of Eagle, Summit and Boulder have adopted residential green building programs.