Environmental impact of constructions made of acetylated wood

In the global climate agreements made during COP 21 in Paris, the role of forests and wood products have gained more attention considering their important impact – both negative and positive – through deforestation, forest conservation, afforestation and increasing application of wood in durable (construction) products acting as carbon sink. A promising route enabling legally and sustainably sourced non-durable temperate wood species to be used in high performance applications is through large scale non-toxic wood modification, of which acetylation is one of the leading methods. Acetylation has proven to enhance the resistance against fungal decay and dimensional stability of wood such that on commercially base two heavy load-bearing traffic bridges have been constructed. In this paper a cradle-to-grave assessment is executed to compare the environmental impact of acetylated Scots pine, tropical hardwood (Azobe) and non-renewable materials (steel, concrete) with the bearing structure of a typical pedestrian bridge as unit of comparison (‘functional unit’) The results show that acetylated wood has a considerably lower carbon footprint than steel, concrete and unsustainably sourced Azobe, and like sustainably sourced Azobe can have CO2 negative LCA results over the full life cycle.