This session will share insights from three research projects focused on greenhouse gas impacts of efficiency-related measures. The first project assessed how the choice of insulation materials in new construction affects the building’s carbon footprint. Two Vermont homes participated in a pilot program in which common insulation materials were substituted for lower embodied carbon alternatives. Understanding that weatherization helps ensure the useful viability of our existing building stock (beyond the environmental, financial, land-use, and embodied carbon benefits), the second project focused on five years of weatherization data through the Home Performance with ENERGY STAR program. It identified trends in use of insulation materials, assessed GHG impacts associated with thousands of projects, and highlighted opportunities for reducing embodied carbon. The final project analyzed the lifecycle carbon impacts of using heat pumps to offset fossil fuel boiler heat. The case study analysis compares fossil fuel boiler emissions to dynamic emissions factors of the electric grid, embodied carbon of new heat pumps, and heat pump fugitive emissions from refrigerant leaks. You’ll hear lessons learned and what opportunities exist for the future. These projects each investigated the carbon impact of materials and systems applied to new and existing buildings in our cold northeast climate.