When it comes to construction wood is good
Over 70% of the population of the developed world lives in timber frame housing. In Scotland, 60% of new-build houses are timber framed and the figure for the rest of the UK is around 10% and rising as the benefits to builders, developers and occupiers are recognised. However, timber is not just for use in low-rise residential buildings. It’s increasingly being used in the construction of schools, hotels, offices, health care facilities and flats.
Although the prospect of driverless cars on our roads within a decade is entirely plausible, a skyscraper built out of wood still seems outlandish. Why? Wood is one of the world’s strongest, most durable and versatile building materials, yet there remains a distrust of tall, wooden buildings with an unfounded perception that they are prone to destruction by fire.
But it’s the 21st century and technology has advanced. Engineered beams made from Cross-Laminated Timber (CLT) are proven to be just as fire retardant as steel and arguably more so, since their cores as less likely to melt in a fire. Timber producers are now using special polyurethane adhesives to bond planks together, resulting in a material that’s lighter but stronger than steel and concrete and crucially, more environmentally friendly.
This pioneering technology has freed architects to dream up buildings that were previously inconceivable. CLT is now the product most likely to keep executives in the structural steel and concrete business awake at night. It can be used for building entire structures very quickly. The lightweight nature of CLT means foundations can be smaller and cheaper. It’s clean to use with little waste and sourced from renewable softwood forests, which makes achieving high BREEAM ratings easier, as well as contributing to a developer’s sustainability credentials.
Two years ago, developer Lend Lease completed a 10-storey residential block in Melbourne, the world’s tallest CLT project to date, and now engineer Ramboll is working on the design of two 10-storey residential buildings in the UK. Designed by Waugh Thistleton Architects, Murray Grove in London (pictured), a 9-storey residential building built in 2009, was the world’s first multi-floor project to have load-bearing walls, floor slabs, stairs and elevator cores constructed entirely out of CLT.
Wood’s greatest virtue, however, is not its design potential or fire safety but its efficacy in reversing the speed of climate change. Steel and concrete manufacture has a colossal carbon footprint, thought to constitute over 5% of global greenhouse gas emissions. The extraction and refining of non-metallic minerals, including the raw ingredients of concrete, amount to a further 6%. Together, these sources contribute about as much to climate change as all the cars and trucks on Earth.
Timber beats conventional building materials on two fronts. Firstly, it delivers far less pollution during production and secondly, wood is able to scrub carbon dioxide from the atmosphere.
Some scientists speculate that the only way to keep global warming under two degrees Celsius, the defined objective of the Paris Climate Agreement, is to provide for negative emissions. That could involve machines or materials, which eliminate CO2 from the air, or eco-friendly farming practices that trap carbon in the soil. So far, however, the most cost-effective tool for carbon fixing is a tree.
According to a 2014 study from researchers at Yale and the University of Washington, up to 31% of global carbon dioxide emissions could be avoided by building with wood instead of steel and concrete.
“If you build out of wood then you avoid burning all that fossil fuel to make the steel, concrete and brick,” said Chad Oliver, Director of Yale’s Global Institute of Sustainable Forestry. He noted that, because timber weighs less than conventional materials, builders also need less concrete to lay the foundation of a wood structure. When a wood building is finally retired, its component parts can be reused in other buildings, buried or used to produce electricity in biomass-powered generators.
The prospect of deforestation to fuel timber-built skyscrapers and generate electricity should not be a concern says Oliver, who advocates smart forest management:
“As a general rule and this varies from place to place, forests are getting more dense but you don’t want the whole world’s forests uniformly dense. You need biodiversity by thinning some parts of the forest and clearing others to create differing habitats where every species has a home. Logging can also reduce the risk of forest fire. In a dense forest, fire is hotter and spreads more quickly through tightly packed trees but in a managed, thinner forest, a fire might hit a meadow and slow down, allowing time for rain or man to intervene and stop it. If we harvested more of that extra growth instead of letting it rot or burn, we could make a lot more products and use the waste for clean energy.”
Whilst in theory, further growth in the use of timber would seem to be both sensible and responsible, there is potential in the UK for this to be checked. British companies are already grappling with higher costs of imported materials and bracing themselves for further pressure in the months ahead as the Brexit process rumbles on. Research by the Federation of Master Builders found 70% of the 232 UK construction companies it polled had recorded an increase in material prices owing to the pound’s fall in value since the Brexit vote. Anecdotally, SMEs are reporting an increase of 20% in the cost of timber with worries that profit margins will be squeezed as they decide how much of those higher costs they can pass on to customers. Economists have warned that the pound faces further pressure once Article 50, the formal process of leaving the EU, has been triggered.
At commercial joinery, refurbishment and fit-out specialist, Hannaford, it’s our stated aim to minimise the impact of our joinery business on the environment and we take the issue of sustainability very seriously. Wherever possible, the wood we use in our projects is acquired from sources accredited by the Forest Stewardship Council (FSC). Hannaford was one of its first certified members and having this certification is important to the company as Richard Williams, Finance Director, explains:
“Hannaford has been around for over 70 years and we have to think about the future prosperity of the business, which relies on access to sustainably sourced timber, as well as the joinery skills needed to work it. Being a member of the FSC demonstrates our commitment to supporting efforts to ensure the optimum balance of tree planting and timber usage for future generations. There’s no doubt that such a renewable resource has scope to make a huge impact in global construction if managed responsibly and we are proud to work with the FSC in raising awareness of the importance of sustainable forestry.”