Significantly reducing building sector greenhouse gas emissions is necessary to meet state and local climate stabilization goals. Initiatives to decarbonize home and building energy use are enabled by a new generation of advanced air source heat pumps (ASHPs) that provide efficient, comfortable heat even at low outdoor temperatures as well as highly efficient air conditioning in the summer. Coupled with thermal improvements to building envelopes and smart controls responsive to grid reliability needs, ASHPs are displacing the use of fossil fuels for comfort heating while providing a range of economic benefits. Investments to decarbonize buildings are most economical in natural market cycles of building construction, renovation and equipment replacement, and as part of community development initiatives to improve and preserve affordable housing. A growing number of state and local policies and programs are accelerating the rate of efficient electrification of home and building heating to replace fossil fuel heat with increasingly carbon-free renewable electricity.