Nowadays, when designing structural aero-engine components, the engineering team does not only deal with aerodynamics and structural mechanics criteria. Rather, it needs to make more informed decisions based on the value and sustainability contribution of a design concept. This paper proposes a novel approach that combines qualitative sustainability assessment techniques, which are Environmental Impact Assessment (EIA) and Strategic Sustainability Assessment (SSA), with Net Present Value (NPV) analysis to facilitate early stage decision-making in design. A case study, related to the development of a new high-temperature aero-engine component, illustrates how EIA and SSA identify sustainability hotspots for a new product technology, and how NPV is used to assess alternative solution strategies within the hotspot. Within the studied case, the milling process was identified as a sustainability hotspot, therefore two process options - Electro-Chemical Milling (ECM) and Mechanical Milling (MM) - where benchmarked by calculating their NPV in alternative future scenarios, featuring different market and regulatory assumptions. The approach and its constituting models have been preliminarily verified with designers and process owners in co-located industrial workshops.