LEED® v5 brings energy and carbon decisions forward – putting early design choices under the microscope. Project teams are now expected to demonstrate credible operational carbon projections and decarbonization pathways while contending with increased cost pressures, electrification strategies, and evolving performance targets. In practice, many projects either model too late – when options are constrained – or commit too early, when information is incomplete. This session explores how integrated early-stage decision support can help teams make better timed, better informed choices. Using real project examples, presenters will show how teams can evaluate early design options across energy use, peak demand, operational and embodied carbon, and cost – and translate those results into clear, defensible decision logs that support LEED v5 submissions, ZCB-Design pathways, and owner approvals. The discussion will focus on practical workflows that reduce redesign cycles, improve coordination, and help teams build stronger business cases for high-performance outcomes.