As buildings become more energy efficient in their operation, embodied energy and carbon become increasingly important. However, there is limited information to allow accurate comparisons of products. Moreover, construction projects are quite complex, not only regarding environmental issues, but also processes and stakeholders. The study of timber as a structural material in the UK is used in this paper to illustrate these factors. The paper brings together five studies and it considers the decisions and processes affecting the use of timber. The EE and EC of timber throughout its lifecycle are identified, including a discussion of assumptions. The impact of various decisions is assessed and the paper concludes by identifying technical and social factors for the focus of policy makers and the industry.