Regarding our timber study for the Wood Window Alliance (24 April, page 69), it is important to realise that the negative value for embodied carbon was based on the knowledge that the timber would be sustainably sourced from a well-managed forest, and that in the future, most of it would provide energy at the end of its life, either through incineration or at a managed landfill, so generating methane for energy

If the timber were not sustainably sourced, we would have assumed that it would be driving deforestation, and the result would have been radically different.

Similar logic could be applied to other organic construction products, and biofuels.

David Weight, Davis Langdon