Methodological aspects in assessing the whole-life global warming potential of wood-based building materials: comparing exterior wall structures insulated with wood shavings

Abstract

Due to the heavy environmental impacts on the building industry, wood-based building materials are gaining interest. They may improve the indoor climate and have a low carbon footprint compared to steel and concrete structures. This study provides knowledge on the carbon footprint of wood shavings (WSs) and WSs improved with clay as insulation materials. The study defines the lifecycle emissions of five different wall structures, of which two are of conventional type in the Finnish context and three with WSs as insulation. The study follows the EN standards on buildings’ life cycle assessment with a streamlined approach and discusses the applicability of the method in the normative context. The study analyzes multiple methodological aspects, including biogenic carbon, co-product allocation, and defining the functional unit in wall structure comparison. In the base case, the exterior wall using WS as insulation provided the lowest GHG emissions of the compared structures. The study finds global warming potential (GWP) of WSs moderately sensitive to allocation choices and energy sources used in the drying of WSs with clay, while the End-of-Life treatment option can radically change the results in biogenic GWP. From the perspective of applying the buildings’ life cycle assessment in the normative context, there is a call for further research for controlling uncertainties in modeling End-of-Life options of biogenic materials.