Comparison of environmental impacts of structurally equivalent wood-based floors

In recent years, in Europe, the use of wood-based products for structural solutions has increased, mainly because of the recent technological developments (e.g. development of products for high-rise buildings) and of the environmental benefits of wood-based products (e.g. carbon content of wood products). This study proposes a methodology based on life cycle assessment (LCA) approach to define a structurally equivalent functional unit for the comparison of the environmental impacts between wood-based solutions for building’s floors. The proposed methodology comprises five main steps: definition of the functional equivalence; definition of structural solutions; structural analysis; design of structural products; and calculation of the volume of structural products. This method was used to compare the environmental impacts from cradle-to-grave of structurally equivalent solutions for floors made of wood-based products with various strength and stiffness properties: solid wood (SW; softwoods and hardwoods); glued laminated timber (GLT); I-joists (IJ); and laminated veneer lumber (LVL). The results showed that, during the production stage, softwoods have the lowest environmental impact in the majority of the categories assessed. On the other hand, hardwoods (in particular D30) showed the best environmental performance during the entire life cycle. The discussion of results showed that the preliminary sizing rules have a high influence on the impacts of products with higher strength and stiffness properties. The results were compared per cubic meter and per structural solutions and showed that the products with higher strength and stiffness properties have a higher variation between the two results. The consideration of energy recovery at the end-of-life of products reduces the life-cycle environmental impacts of the structural solutions.