Reducing embodied carbon emissions of buildings and building materials.

Washington's HB 2273 requires large new construction, additions, and renovations (100,000+ square feet, excluding school districts) to reduce embodied carbon emissions from building materials. Projects can comply through three paths: reusing at least 45% of an existing structure, demonstrating reduced emissions for 90% of covered materials using environmental data, or conducting a whole-building life-cycle assessment comparing to a functionally equivalent reference building. All projects must report compliance data to a public database managed by the Department of Commerce, including details like project size, compliance method, and material usage. The bill establishes reporting templates and requires design professionals to verify emissions calculations before project completion.