Life Cycle Assessment of a Hybrid Biobased Panel for Insulated Concrete Forms Used in Residential Buildings

Abstract

Buildings are a large contributor to climate change, as they require large amounts of fossil energy to maintain indoor comfort for occupants, either as heating in cold climates or cooling in warmer climates. Insulation materials (IMs) prevent heat transfer and provide energy savings, while achieving comfortable indoor environments. In the last couple of decades, there has been a considerable number of life cycle studies on petrochemical, mineral, biobased or hybrid IMs, to determine their environmental impacts and assess their contribution to life cycle impacts of buildings. These studies show a range of impacts associated with the manufacture and use of these IMs due to activities associated with the production of raw materials and aggregates utilized to create the final product. Dematerialization and circular economy principles are being applied in the design of building materials in an attempt to reduce their impacts. However, each novel hybrid IM needs to be assessed holistically to determine its sustainability. For example, using by-products as raw material might reduce the environmental burdens of IMs, while encouraging efforts towards preserve biodiversity, ecosystems protection and human welfare. The aim of this research was to evaluate and compare the environmental performance of a new hybrid material produced from biobased residues and by-products, and industrial by-products. Specifically, the analyses consider the use of a biobased (CSB) panel of corn stover, fish waste binder, and cement kiln dust (CKD), to replace conventional extruded polystyrene (XPS) panels in insulated concrete form (ICF) wall systems. The environmental impact assessment was performed using an ISO-compliant Life Cycle Assessment (LCA) methodology and considering system boundaries from cradle-to-wall gate and using a functional unit of one square metre of wall, which was structurally equivalent and had an insulation value of RSI=1 (m2K/W). The impact assessment methodology used was TRACI 2.1. The CSB panel had lower impacts on a mass basis than the XPS panel; however, the CSB-based wall system had higher impacts in most impact categories than the XPS wall system due to the higher mass of CSB panel required to meet the functional unit. Specifically, the global warming potential was 65.7 KgCO2eq for the CSB wall compared to 49.4 kgCO2eq for the XPS wall. The impacts of the CSB panel were driven by the corn stover production, specifically the energy required to collect the stover, and the use of CKD, because cement production is known for its high impacts. Although the CBS panels were made from residues and by-products, their impacts are higher. Therefore, research is needed to understand how to reduce these impacts, including replacing the CKD, and exploring the use of the CSB panels in other building applications, such as drywall replacement in indoor walls, where insulation is not needed and mechanical strength does not have to be as high.