To achieve deep decarbonization goals by mid-century, Pacific Coast states, the province of British Columbia, and cities need to significantly reduce greenhouse gas emissions across all economic sectors. PCC jurisdictions are committed to collaborate on ways to lower the carbon intensity of heating fuels in the residential and commercial building sector—known as thermal decarbonization—as a key step on the path to net-zero building energy use. In a policy brief, the PCC summarizes key solutions and regional principles to guide work in the area of thermal decarbonization. Strategies for deep decarbonization primarily focus on the pillars of using less energy, decarbonizing electricity, decarbonizing liquid and gaseous fuels, and switching fuels. These are tightly intertwined parts of an integrated approach, and they present complexities that will have to be addressed in a coordinated and thoughtful manner. Thermal decarbonization policy development and implementation will play out differently across regional jurisdictions, which represent a diverse array of climates, economic drivers, electricity generation mixes, and renewable energy opportunities.