An Act relative to building energy and decarbonization

This bill creates a "green plus community" program requiring municipalities to establish emissions baselines, commit to reducing emissions by at least 20% within 5 years, adopt specific energy codes, and develop implementation plans. It also establishes annual carbon intensity limits for large buildings, allowing for building-use-specific standards and alternative compliance methods (including reduced payments for low-income buildings). The bill increases funding for community programs to $40 million (with $10 million reserved for green plus communities) and creates a Building Energy and Emissions Retrofit Funding Program to support deep energy retrofits, excluding fossil fuel system conversions. These provisions directly affect municipalities, building owners, and developers of large commercial, industrial, and residential properties.