An assessment framework for the sustainable use of UK timber

Timber is an attractive material choice for minimising the environmental impact of engineering projects, as it commonly has a lower embodied energy than its synthetic counterparts and it can remove and store carbon from the atmosphere. Timber is also renewable, however, it takes decades for trees to mature, so it is vital that forests are managed sustainably.

To combat deforestation, global forest certification schemes ensure timber is produced from sustainably managed forests. It is therefore good practice for certified timber to be used by engineers. Furthermore, transportation can account for the majority of the embodied carbon of procured timber [1], so timber should also be sourced from local forests, to minimise environmental impacts.

In a UK context, this presents a problem; the UK is the second highest net importer of timber in the world, due to its high timber demand and low domestic timber stock, all while the UK government is below its tree planting target [2]. Thus increased use of domestic timber could become unsustainable for UK forests. To complicate matters further, UK forests are changing; forest managers are transitioning away from monoculture plantations to more diverse woodlands that offer greater resilience to disease, pests, and climate change [2].

A sustainable use of UK timber must consider the limitations to domestic timber supply, through using timber both more efficiently and from a diverse range of species. However, this consideration is currently missing in the environmental assessments of timber found in the open literature.

Currently, the most common method to quantify the environmental impact of timber use is a life cycle assessment (LCA). However, commonly used LCA methods often omit key environmental impacts relating to forest land use and land use change [3]. LCA methods are being improved in the literature, which is providing greater insight into the environmental impacts of different forestry methods.

However, these advanced LCA methods require compiling and improving before they can be used for a holistic assessment of an engineering project.

This project aims to produce a framework that allows for a holistic assessment of the use of UK timber in engineering projects, taking into account timber availability and supply chains as well as forestry land use and land use change. Life cycle costing and social LCA methodologies will also be included to include all three pillars of sustainability.

The framework will be tested and validated using engineering case studies that use UK timber and range in complexity. The sourcing and design decisions made in each case study will be compared against a business-as-usual baseline scenario and a best-case scenario. This will allow for an assessment of the decisions made, to provide guidance, to the industry, on the future sustainable use of UK timber.

References: [1] "Buildings infrastructure priority actions for sustainability: Embodied carbon, timber," ARUP, 2023.

[2] "Seeing the wood for the trees: The contribution of the forestry and timber sectors to biodiversity and net zero goals," House of Commons Environmental Audit Committee, 2023.

[3] C. E. Andersen, et al., "Whole Life Carbon Impact of: 45 Timber Buildings," Department of the Built Environment, Aalborg University, 2023