B4.1 IgCC
Adopt the International Green Construction Code (IgCC).
The IgCC is one of several available advanced energy codes. According to the New Buildings Institute it’s “more advanced and holistic than the base IECC code or ASHRAE Standard 90.1.” Washington State currently allows local jurisdictions to adopt more demanding energy codes than the State’s for commercial buildings and for multi-family construction over three stories.
Overview of the IgCC by the International Code Council, which developed and promotes it. Architect Magazine published an overview in December 2018 with somewhat more distance, and a discussion of the limited adoption of the first version, introduced in 2012.
The New Buildings Institute has links to several studies of the costs of advanced efficiency measures in commercial buildings.