CHOOSE WOOD

The case of
wood

Construction of buildings can be greener and wood offers a set of advantages and benefits that were ignored for years.

For example, the production of timber beams and pillars requires a fraction of the energy (15%) than that of their steel equivalents.

Perhaps the most surprising benefit is that wood can act as a reservoir of carbon dioxide. The explanation is long, but it's worth it: as a tree grows it removes carbon dioxide from the atmosphere and stores it. When a tree reaches maturity and is harvested, another tree can be planted, which will continue to remove carbon from the atmosphere. Yet carbon is always released when wood rots or burns. So a decade ago, when a plague affected 18 million hectares of forests in British Columbia, this Canadian province had to react quickly because if all those trees were to become decomposed or burned in forest fires, Canada's carbon emissions would increase by 2% for the period 2000-2020. In 2009, British Columbia enacted a law that requires the use of wood in all new buildings with public financing.

The ability of solid wood to sequester substantial amounts of atmospheric carbon, together with advances in technology and the development of materials - such as solid panels formed by multiple layers of boards placed in different directions to optimize fiber resistance - make it a worthy rival for steel and concrete for use in the structure of a building. The development of LSL panels (Laminated Strand Lumber), LVL (Laminated Veneer Lumber) and CLT (Cross Laminated Timber) were a turning point for Michael Green. “The 8-point Lego bricks”, he explained, “serve to build many entertaining things. But one day you find a brick with 24 points, and it's 'Wow, it's amazing. I can build something very big and this is going to be spectacular'. That is the change. The solid panels are the 24-point bricks", he said.

In addition, since lumber is light, buildings could be produced in factories and assembled on-site, which reduces the impact of transporting materials to construction sites. In fact, the British architect Andrew Waugh, another pioneer in the use of CLT in wood constructions, highlights the precision, speed and cleanliness that the use of CLT entails. In his exhibition at the Comad Fair in Chile, at the end of 2018, he shared his experience on the construction of Murray Grove, in London: the structure of a nine-story building can be built in 27 days with four carpenters. The use of the panels results in cleaner and quieter construction sites, since instead of drills, cement mixers and welders, there are only teams of people joining panels with cordless screwdrivers. And they generate less waste than a traditional construction.

Finally, wood can be recycled. Parts of a building can be disassembled and reused, ensuring that the carbon remains trapped in its fibers.