The most sustainable material of them all

Sean Parnaby of West Port says that the timber industry is gradually winning the war against misconceptions about what he claims is not only the oldest, but the best fenestration material

There’s a growing awareness that timber isn’t the expensive, maintenance-heavy material many people think it is – and that its poor reputation in some quarters has nothing to do with timber itself, but stems instead from the cheap and shoddy mass-produced wood windows of the mid-20th century. But one of the most stubborn timber myths concerns sustainability. Many people still incorrectly assume timber windows and doors are bad for the environment, but that’s not true. Timber, when it’s ethically sourced, is the greenest fenestration material of them all. Increasingly, you hear claims that PVCu is the most eco-friendly and thermally efficient fenestration option on the market – understandable given growing public interest in minimising their environmental impact, and ever-rising heating bills.

But they’re false. A unit’s energy efficiency is determined by the glass, not the frame – and far from being the greenest option available; PVCu is actually the worst polluter among window materials. Making a PVCu window pumps 160 kg more carbon dioxide into the atmosphere than making a timber one does. And recycled PVCu windows can contain lead, cadmium and mercury, all of which are released as toxic gases when exposed to extreme heat, making them highly dangerous in fires. Many people associate timber with deforestation – people irresponsibly cutting down sections of forest, and never replacing the trees that are removed. But ethical timber is a different phenomenon entirely. Sustainable timber products come from well-managed forests, where new trees are planted to replace those that are harvested.

Planting new trees means that even more CO2 is stored, making sustainable timber products better than carbon neutral. Academics from Heriot Watt University, renowned worldwide for its construction expertise, conducted a comprehensive Life-Cycle Analysis on a variety of timber windows and compared them with PVCu alternatives. They found that using timber to make windows could make ‘a significant contribution to low-carbon building’. This is for two key reasons. The first is that timber itself is a low-carbon material, and the second is that timber offers low thermal transmittance, meaning timber windows offer excellent thermal efficiency and allow homeowners to use less energy to heat their homes.

Wood was also found to have ‘significantly lower’ environmental impact than PVCu alternatives. In fact, all the wood windows tested as part of the study were concluded to have negative global warming potential and be carbon negative over their entire 60-year average lifespan. These outstanding ecological credentials are reflected in the fact that the Building Research Establishment’s Green Guide rates wood windows as A or A+ for their minimal environmental impact. Timber is also highly durable, with some well-made wooden structures lasting for centuries. It also helps to meet increasingly strict government regulations aimed at reducing the construction sector’s environmental impact. With timber, you don’t just ensure you meet today’s legislative requirements, you future-proof your project against measures that could be introduced in future, and increase your chances of getting through the planning process. In fact, timber is without a doubt one of the most environmentally friendly, high performance building materials available today and for the future.

Sean Parnaby is managing director of West Port