Problems encountered in the life cycle assessment (LCA) of recycled materials in construction

The establishment of sustainability credentials of emergent construction materials is very subjective, and most available tools such as BREEAM, CEQUAL, ARUP SpeAR among others are not fully quipped or equipped at all to deal with individual material systems. The main problem emanates from the challenges of the audit of each aspect of the material processing, and especially the quantification of the relevant transport, energy, environmental and other inputs into the composite product. Incorporation of materials with long and complex recycling processes further exacerbate the challenge. This paper reports on a simplified approach towards full Life Cycle Assessment (LCA) of seven clay-based brick products developed in UK and in Spain, based on known material data and estimated energy inputs in the manufacturing processes. In order to test the robustness of the proposed approach, results on UK-based bricks are compared with a parallel LCA on clay-based product developed in Spain. Finally, the clay-based products are compared with a typical Portland cement-based concrete block and fired clay brick. In the LCA, boundary conditions include fixed transport, thus attempting to factor only the (i) material ingredients, (ii) their known atmospheric emissions, and (iii) estimated energy inputs during processing. Results suggest that the most challenging aspect in the undertaking of LCA is the availability of reliable input data. Results also show that there are numerous parameters that can reliably and corroboratively facilitate the comparison of performance, besides carbon dioxide emissions.