Towards an Integrated Process Framework for Life Cycle Carbon and Cost Assessment of Buildings

While the potential for minimizing carbon emissions of buildings is increasing, the intricacies of the associated cost premiums remain a grey area. Presenting a viable case of cost competitiveness is however critical to the widespread adoption of low carbon buildings. With cost premiums expected to be rationalized over the building’s lifespan, integrating Life Cycle Assessment (LCA) with Life Cycle Costing (LCC) can provide a comprehensive overview of the apparent carbon-to-cost trade-offs. In this paper an Integrated Process Framework for LCA-LCC is proposed. Following a review of 23 case study papers identified from Scopus search, the goal/purpose, standards, approaches, and scope of LCA and LCC are analysed. The findings show main use cases in comparative carbon and cost assessments for alternative building solutions. The ISO 14040 and ISO 15686 series are identified as the most adopted standards for LCA and LCC respectively. For LCA, the Process approach is applied in most studies, while the Conventional approach is most applied for LCC. Generally, the LCA system boundaries span across cradle-to-grave, with LCC showing a decreasing inclusion of cost scopes from Initial to End-of-life costs. A key gap identified across the case studies is the lack of a consistent methodological framework for integrating LCA and LCC. This can be attributed to challenges identified to include limited access to data, limited scope of assessment, as well as limitations in evaluating trade-off impacts. In view of this, a 12-step integrated process framework for LCA-LCC is proposed within a standardized workflow. The conceptualized framework accommodates the integration of critical LCA and LCC assessment parameters including goals, standards, scope, system boundaries, levels of detail, approaches, databases, emission monetization and extended value integration.