Buildings & Infrastructure Priority Actions for Sustainability. Embodied Carbon. TIMBER

With the building and construction industry accounting for 40% of annual CO2 emissions [1], decarbonising the buildings sector is imperative. In the search for lower carbon materials, biogenic materials are gaining popularity due to their potential for reduced global warming potential (GWP), and capability for regrowth to provide a renewable construction resource. It is estimated that global demand for wood products will quadruple by 2050 [2].
The carbon assessment of timber is highly sensitive to sourcing, so it is important that we collectively align our understanding of the lifecycle stages. Each stage from raw material extraction through to maintenance and disposal can require the use of fossil fuels, and therefore a detailed assessment is required. Timber should be treated as a scarce resource and designed with this in mind. This document aims to set out the factors that contribute to the emission of carbon through the whole life cycle of the following timber products:

• Softwood: Used in the construction of internal features such as windows, door frames, joists and roof trusses typically of domestic scale buildings.
• Glued-laminated timber (Glulam): Used for load bearing elements such as rafters, beams, slabs and columns.
• Cross-laminated timber (CLT): Used for surfaces and build ups such as walls and floors.

It should be noted that industry consensus is hard to reach, and this is an evolving subject. This guide is intended to provide a focus for discussion, identifying the ways in which timber can be used efficiently to decarbonise our structures.