CARBON FOOTPRINT OF MASSIVE TIMBER CONSTRUCTION

An assessment of the material production, construction and use stages of European reference buildings

Abstract

 The environmental development of a building has an important role to play in terms of the sustainable development of our society. Against this background, wood and wood-based products, especially so-called massive timber product such as Cross laminated timber (CLT) and laminated veneer lumber (LVL), have lately attracted notable attention as a promising construction material due to their unique environmental properties like renewability and carbon storage capacity. The development of sustainable wood construction has become a matter of public interest.

 The aim of this research is to clarify the environmental features of massive timber construction. This study reports on a detailed investigation into the carbon footprint of multistory massive timber buildings. Based on the life cycle assessment (LCA) method, CO₂ emission associated with the production, construction and use stages of the reference buildings and temporal carbon storage (TCS) in the buildings were quantified.

 The assessment results were analyzed in accordance with the life cycle stages, building element categories, building parts categories and building material categories. The features of massive timber construction in terms of carbon foot print and possible practical development were discussed. Main findings are summarized as follows:

 1) The material production (Module A1-3), construction (Module A4-5) and use (Module B6) stages account for, respectively, 17-27%, 4-10% and 63-79% of the total emission of the included life cycle stages.

 2) TCS was equivalent as the emission for Module A.

 3) The multifunctionalization of massive timber as such based on the inherent properties of wood would be a mean to use wood more reasonable way, reducing the emission and enhancing TCS as a benefit.

 4) Because of high possibility to use biomass fuel in the process, there seems to be greater potential to mitigate CO₂ emission from the prefabrication than in the on-site construction.

 5) It happens that the transportation of building components (Module A4) results in higher CO₂ emission than the actual construction work (Module A5), due to the long delivery distance for massive timber products. It would be fundamental to select proper material in accordance with conditions of a project such as location, purpose and scale of a building.