Building the future with timber
Sustainable timber design has economic, environmental and social benefits, as Peter Wilson explains.
The concept of sustainability has been with us for some time now but awareness of how it can be delivered is still insufficiently widespread to make the dramatic impact required on construction, energy and end-of-life reuse. Unnecessary waste in all three areas is still the norm, with the construction industry globally remaining one of the biggest contributors to greenhouse gas emissions and environmental pollution. The story is not all bad, but a sea change is required in both attitudes and knowledge within the industry if we are to avoid the soon-to-occur 2°C increase in global temperatures that scientists predict will radically – and detrimentally – alter the way we live on the planet.
To be more positive, there has been a considerable number of buildings constructed over the past decade that demonstrate what is possible when there is a collective will to behave more responsibly in the way that we use the world’s resources. Far from being the stuff of Luddites, three examples illustrate a few of the different approaches taken during that period and the advanced nature of the thinking involved.
Leading the way
Brockholes Wetland and Woodland Nature Reserve Visitor Centre by Adam Khan Architects can be found just north of Preston at Junction 31 on the M6 and is an essential stop for motorists who prefer to avoid the unmemorable and expensive catering facilities of many motorway service stations. Brockholes is very different – not only does this haven of peace lie within the shadow of the busy motorway but the centre itself is a cluster of buildings sitting atop a pontoon that rises and falls on the ever-changing water levels of a flooded former gravel pit. Similar facilities can, of course, be found at other visitor centres, but here they are separated into different units of accommodation to form what is effectively a floating village constructed almost entirely from timber and engineered timber products.
While design inspiration for this unusual group of barn-like buildings began with the vernacular of traditional marsh settlements, the architectural and engineering approach and the technologies employed are thoroughly modern. The desire to create a truly sustainable development lies at the heart of this project, with its steeply pitched asymmetric hipped roofs clad in oak shakes roughly cut from tree stumps and eaves that are set at a human-scale 2.3m, the height of the surrounding reeds. Crisply machined vertical oak slats clad the walls to create an indefinable, timeless appearance that has gradually weathered to grey.
So much for the exteriors – inside the story is very much one of precision engineered timber in which vertical posts support V-shaped glulam braces set at the angle of the roofs to form a concertina of inclined portal frames. Innovation is not confined to the structural design of the various buildings however, as a raft of complementary energy and carbon reduction measures ensured extremely high environmental standards were achieved. It was subsequently rewarded with a BREEAM Outstanding (Design Stage) rating and an A Energy Performance Certificate. The structural timber and oak roofing shakes were thus far from being arbitrary design choices, but the result of a whole-building energy analysis that produced a specification of low embodied energy materials. It also produced an environmental strategy that called for natural ventilation throughout, state of the art glazing and insulation, rigorous draught proofing, grey water use and a biomass boiler.
A second visitor centre – this time at the Culloden Battlefield near Inverness in the Highlands of Scotland – had already set the bar high, with a design intention by Gareth Hoskins Architects for the building to be fully deconstructable with all materials re-useable at the end of its pre-determined lifespan. Wherever possible, locally sourced materials were used in order to minimise the embodied energy and cost inherent in transportation. The solution was to design a steel frame – not in itself a locally produced material, but ultimately reusable – and to fill and clad it with timber products sourced from within a 50 mile radius. Wood from nearby forest estates provided the larch cladding, oriented strand board (OSB) manufactured near the Highland capital from locally grown Scots pine was used for the roof decking that sits upon engineered timber I-beams – a product that is also manufactured in the vicinity. Other building elements include internal timber linings made from oiled oak joinery and untreated Scottish larch.
Overall, the building has a small surface-to-area ratio to minimise heat loss, while orientation and roof form were manipulated to maximise glare-free daylight and natural ventilation. The curved roofs that form overhangs to the south-east glazed terraces provide shading and shelter. Internally, the challenge was to design a naturally ventilated building responsive to extremely high visitor loads during the high season. The resulting ventilation system operates passively through the use of opening windows and low-level vents, with high-level ventilation achieved via parapets and roof cowls. The system is generally wind-driven, orientated towards the battlefield and prevailing winds.
The third of these examples is the Savill Building by Glenn Howells Architects, another visitor facility that sits within Windsor Great Park and takes the concept of local sourcing to new heights – almost all of the timber used in its construction came from within the bounds of the park itself, a matter of a few hundred metres. This is no folksy solution, however, but a highly engineered and groundbreaking use of park-grown oak and larch to create a distinctive, three-domed, undulating gridshell roof structure, the largest of this type in the UK. Double-curved, larch laths were used to create the internal gridshell structure with oak forming the outer rainscreen.
The new order
While these early examples indicate different approaches to sustainable design and construction, they nevertheless demonstrate a direction of thought that has long since moved beyond recreational buildings into other sectors, such as commercial, educational and industrial buildings. Convincing evidence of why this might be so is to be found in recent analysis by the Danish financial institution, Nykredit, of sustainability and financial performance data for more than 5,000 global, publicly traded companies. The results clearly show that equity returns from listed companies with a strong sustainability profile far exceed those of companies in general. Put simply, larger companies are now beginning to realise that it pays to invest in environmental and social sustainability.
Clear demonstration of this can also be seen in the way commercial buildings are increasingly being marketed – a recent billboard outside a Canadian construction site, for example, proudly proclaims the new building will be ‘LEED Platinum’, the highest accolade of the North American ‘Leadership in Energy & Environmental Design’ green building certification programme that recognises best-in-class building strategies and practices. When developers are pitching to both clients and public, you can be sure real change is afoot, and anecdotal evidence from this same marketplace indicates that potential employees are beginning to question prospective employers as to whether they will be working in a ‘LEED Platinum’ environment. More than size of salary or bonus, commitment to sustainability could well be the new deal breaker when seeking top quality staff.
A recent UK example indicates just how far this new responsiveness to sustainable design and construction is impacting on our own business community. Under the banner of ‘Believe in Better Building’, BSkyB’s new education facility for graduates, apprentices and staff training has been designed to reflect the company’s sustainable aspirations. Based at the Campus in West London, the 3,000m2 development encompasses a four storey linear building, accommodating a restaurant and top floor roof terrace. The educational facility is the first in a series of initiatives using the power of television, creativity and sport to help young people achieve their potential by gaining the skills, experience and inspiration needed to help prepare them for the world of employment.
The structure was designed to deliver permanent quality, adaptability and long-term energy efficiency. The overall objective was to construct a low energy structure within a short time period (the project had to be completed in time for BSkyB’s 25th anniversary celebrations) – making solid timber and timber cassettes the optimum rapid and sustainable solution, as these products eliminated the requirement for wet trades onsite, thus making an accelerated programme of works eminently achievable. The solid timber frame – a glulam frame with visible grade cross laminated timber panels to provide core stability to the walls and floors – has been left largely exposed within the finished structure to deliver the natural look and feel required by BSkyB to visually represent the company’s environmental ethos, whilst the timber cassettes delivered the low thermal resistance and high airtightness required to meet the challenging design brief.
As more and more larger-scale examples emerge, there is no doubt that the concept of sustainability has moved well beyond mere fashion and is now delivering mainstream economic value as well as environmental benefit – without doubt, a win-win.
Peter Wilson is a registered architect and director of Timber Design Plus.