To address concerns and possible confusion over using supplementary cementing materials (SCMs) in concrete, an EcoSmart-led partnership has developed a ‘SCM Optimization System’ (SOS). This web-based decision-making system allows developers, architects, engineers, contractors and material suppliers to optimize the use of SCMs in concrete by simulating the effects of varying the multitude of parameters that interplay on construction projects. SOS can be used at all stages of construction – through concept, structural design, materials selection and proportioning, to construction management and implementation.  By determining optimal SCM levels and tradeoffs, the system enables users to reduce greenhouse gas emissions and construction costs, and lower the environmental footprint by directly reducing the amount of Portland cement required for construction projects.