The Existing Building Decarbonization Code is a new way for jurisdictions to reduce carbon emissions and meet Climate Action Plan and public health and equity goals. The need to address existing building stock is great, with 5.9 million existing commercial buildings in the U.S. comprising 97 billion square feet. New construction represents less than 2% of building activity in any given year, leaving a vast amount of outdated technologies in current building stock. NBI’s release of the Building Decarbonization Code provided the first off-the-shelf solution--as an overlay to the 2021 International Energy Conservation Code (IECC)--for jurisdictions to transform energy codes into decarbonization codes for new buildings. Expanding where that document left off, the Existing Building Decarbonization Code complements the original adding provisions specifically for existing buildings. The new model language covers both residential and commercial buildings including all-electric and mix-fuel energy use pathways.