A project pursuing LEED BD+C certification is designed with an electric air-source heat pump as...

An all-electric supplemental heating system maintains reliability without introducing on-site fossil-fuel combustion. Auxiliary heat-pump capacity or appropriately designed electric-resistance backup can operate during low outdoor temperatures when the primary heat pump cannot meet the full load. A natural-gas boiler would produce direct operational emissions even when used infrequently and would weaken the project’s electrification and decarbonization pathway. Biomass combustion also creates on-site emissions and should not automatically be treated as carbon-neutral because its climate impact depends on fuel sourcing, combustion efficiency, supply chains, and accounting boundaries. The team should first reduce peak heating demand through envelope performance and then size the all-electric system for design conditions. This approach aligns with LEED v5’s explicit focus on operational emissions and near-zero-carbon buildings.