Potential cascading of wood from the built environment in Finland

Construction and demolition waste is a concern today because many building components have a high intrinsic resource value, providing both an environmental and economic incentive for recycling and re-use. Of all building materials, wood is becoming an increasingly important resource, being both biotic and renewable. However, there are limits to how much can be sustainably harvested and, therefore, reuse (and recycling) of the material is vital. This is a priority in the EU and national regulations to develop empirical approaches for the efficient use of natural resources. Thus, the cascading concept becomes a declared goal of European policy as it concentrates on the efficient utilization of resources by using recovered wood in second-life applications. However, implementation of the cascading concept requires studies into when, where and in what quantity and quality the wood can be extracted from buildings. Therefore, the aim of this thesis was to investigate which building types have the highest share of wooden construction, and what quantity of wood is available in them. Further, a method was developed to determine when the wood elements could be cascaded. For this, a three-part methodology was developed to answer the aforementioned questions. Firstly, the building types comprising the higher share of wooden buildings by gross floor area (GFA) were identified through a funnel methodology. Their GFA was compared by gathering information regarding the wood used in buildings, and their overall GFA by intended use. Secondly, a wood stock analysis was applied to estimate the mass of wood in the buildings, by multiplying GFA and the wood intensity of building types constructed in different years. Thirdly, outflow analysis was developed to project the future demolition of wooden buildings, by GFA. The approach initially models the history of demolished GFA of buildings with the most likely reasons for demolition retrieved, then proposes future scenarios for the forecast of demolition by GFA. The study identified that in 2017, attached and detached houses accounted for the highest share of wooden buildings among all buildings. Overall, 85,64% of detached and attached houses by GFA comprise wooden buildings. The results also show that the aforementioned buildings contain 17, 50 megatons wood, highlighting the relevance of wood products in buildings and raising awareness of the cascading potential, and the importance of investigating the quality of, recovered wood. It also discusses the validity of the proposed outflow model as an alternative approach for forecasting the outflow of wood