SmartCarbon was an Industry-Academia–Venture fund collaborative project involving Thinksmart Technologies, University College Cork and the National Digital Research Centre. The project involved the development of decision making tool based upon Multiple Decision Diagrams (MDDs) for consideration of building energy retrofit options. Candidate retrofit alternatives including associated key performance indicators (KPIs) (e.g. cost, energy, embodied carbon) can be compiled into MDDs where various performance implications can be effectively illustrated and KPI trade-offs explored.