Kingsgate House in central London is being billed as a milestone for the Programme for the Endorsement of Forest Certification (PEFC), and possibly timber environmental certification generally. The seven-storey, crosslaminated timber-based apartment block, built by Willmott Dixon on the Kings Road, is the first major development globally to secure PEFC Project Certification.

This guarantees that the majority of timber is certified legal and sustainable under the PEFC’s certification scheme, while the rest is from otherwise guaranteed environmentally-sound sources. Willmott Dixon’s achievement is seen as significant by the PEFC on two counts. There’s the certification breakthrough itself,

but also the fact that Kingsgate forms part of a growing trend towards large-scale structural use of engineered wood products in the UK and elsewhere, particularly in urban developments. This in turn, it says, creates prime conditions for PEFC Project Certification to take off, with Kingsgate potentially lighting the blue touch paper.

Willmott Dixon received its certificate from Alasdair McGregor of project auditor BM TRADA at an event at the Building Centre in London, attended by more than 100 people from the timber, building and architectural sectors, housing associations and local authorities

PEFC UK secretary-general Alun Watkins said the organisation had issued project certificates previously in Spain and Italy, but just three and for individual private houses. "Kingsgate is a first because it’s on a different scale," he said. "We’re excited about it and feel the lessons learned on the project and its promotion will move Project Certification forward everywhere."

The growing use of CLT and glulam, he said, would provide added impetus.

"The majority of these solid wood solutions are from PEFCcertified origins and schemes using them find PEFC Project Certification readily achievable." To be project certified, and subsequently use the PEFC logo, a building has to have a minimum of 70% PEFC-certified timber, with the rest from approved controlled sources. Kingsgate, which uses prefabricated CLT panels from KLH UK, is 96.5% PEFC material, with the balance FSC certified.

Chain of custody checklist

Steve Cook, principal sustainable development manager at Willmott Dixon’s WD Rethinking consultancy, said the project posed some challenges.

"It was a learning curve to monitor every piece of timber coming on site and the education process had to engage the whole team, from sub-contractors, to site gatemen," he said, adding that everyone involved was issued a credit card-sized chain of custody (CoC) checklist.

"Procedures had to be very robust," added Mr McGregor. "There had to be full chain of custody to the site gate and critical control points where there was greatest risk of losing a product’s physical identity. Everything had to be logged into a computer database and, besides the initial and final meetings and audit, we undertook site visits during construction to ensure systems were working. Overall it was an excellent performance by Willmott Dixon."

Adding to the need for strict controls right down the supply line was the fact that the 1,345m² Kingsgate site was so tight for space that the KLH panels had to be hoisted immediately into position from trucks. As a result, there was scant room to quarantine questionable material and suppliers were warned that products with less than perfect CoC would be turned away.

"The strength of the process was highlighted by the fact that we only had two instances where we had to track back a few stages to verify CoC," said Mr Cook. Willmott Dixon and Kingsgate architects Horden Cherry Lee agreed that structural use of engineered wood products had a strong future.

The benefits of the material included its applicability to advanced prefabrication and lightness. The latter enabled Kingsgate to be erected on the foundations of a previous building and the CLT elements to be delivered in 23 loads, against an estimated 200-plus required for reinforced concrete frame.

"This and the nature of the material also results in a quick, relatively quiet building process, both important in urban areas," said architect Stephen Cherry. According to Mr Cook,

engineered timber’s other key attraction to builders, given the global drive to sustainable construction, is its green credentials; with the material being inherently energy efficient and engineered panels scoring well in airtightness and acoustic and thermal insulation.

Critically the material also boasts high embodied carbon, with Kingsgate’s 1,091.7m³ of CLT holding 819 tonnes, the equivalent of 20 years’ operational emissions from the building.

Certification appeal

Mr Cook agreed that the growing value attached to timber’s environmental benefits in construction and the fact that engineered wood-based building is so inherently suited to PEFC Project Certification, meant the two should grow hand in hand. "The EU Timber Regulation is also likely to increase certification’s appeal," he said. "After PEFC and FSC aligned their schemes to its legality requirements, they’re seen among the key routes to helping ensure compliance."

Mr Watkins accepted the PEFC had lagged somewhat on Project Certification, given that FSC started its scheme earlier. But after Kingsgate this will change. "We also envisage increasing uptake of joint PEFC/FSC Project Certification, which was what was effectively achieved for the London Olympics site," he said. Timber Trade Federation chief executive John White viewed the presentation as a "key moment". "CLT and other engineered materials are the products for the future on environmental and performance grounds," he said. "Project certification will add to their momentum."