Using sustainable building materials is gaining a significant presence in the US. This study examined hardwood lumber manufacturing using life-cycle inventory methodology. Material flow and energy use were identified for hardwood sawmills in northeastern US. A hardwood log volume conversion of 43.7% to planed dry lumber was found. Values of 608 MJ/m3 of electrical and 5800 MJ/m3 of thermal energy were determined for the manufacturing of planed dry hardwood lumber where mostly green wood residues were burned on-site for energy. Emission data produced from modeling estimated biomass and fossil CO2 production of 428 and 139 kg/m3, respectively. Increasing wood fuel use, a carbon-neutral process, would lower the environmental impact of hardwood lumber manufacturing and increase its use as a green building material