The National Strategy for Sustainable Construction in Denmark (in 2021) has agreed to include new requirements in which the building environmental impact calculation will become mandatory. We present a general decision-support system framework that delivers LCA information on highly uncertain early-stage designs, aimed at architects and architect engineers. Our key contribution is that we define a new sustainability opportunity metric assigned to early-design BIM model components. Our metric identifies sustainability opportunity “hot spots” (opportunities and risks) based on rapidly envisioning and qualitatively evaluating tens to hundreds of “what if ” scenarios that account for early-stage design uncertainty. A prototype demonstrates two visualizations of our metric on two BIM models.