Ara builds carbon–storing timber building

News News & events

17 Jun 2016

Wood is back.

Internationally, engineered wood products are revolutionising the building industry in a trend that emerged in Europe some 10 years ago, was championed by Canadian architect Michael Green and is now taking off in Australia and New Zealand.


The new Kahukura building - future generations of engineering and architectural studies students

The new Kahukura building at Ara Institute of Canterbury is currently under-way and it looks different to other constructions around town; instead of layers of steel and concrete, there are columns and beams of timber reaching upwards. Built, fittingly, to house the Engineering and Architectural Studies department, Kahukura is not the first new construction in Christchurch to use the timber technology Laminated Veneer Lumber (LVL) as the structural frame. Neither is it the first to use Cross Laminated Timber (CLT) as the structure of the facade. However the combination of materials, with concrete and steel playing secondary roles, makes for a building that is elegant, strong enough to withstand seismic activity and has significantly reduced its environmental footprint by storing carbon in the timber elements.

Yes, by storing carbon.

That is a massive step for an industry that has defaulted to concrete and steel for the last 100 years. Simply put, wood takes a lesser amount of energy to create – the sun does the work – and then it also stores carbon. So the more wood that a building uses, the more it reduces its environmental impact, given that this wood is from New Zealand's sustainable plantation forests. With engineered wood products, where panels of wood are glued and pressed together, this natural product has become stronger and more standardised.

International context - how high can wood go?

Internationally, architects and engineers are now looking at how high these wood buildings can go; the tallest is currently in Melbourne at 10 storeys but PLP Architecture and University of Cambridge recently revealed a concept for London's first wooden skyscraper – a 300-metre-tall, 80 storey, residential wooden framed tower. 

In Christchurch we have far more modest building heights. Wood is a technology that could be embraced for the rebuild.  

Architect Richard Hayman from Jasmax explains. "LVL framed buildings have not been widely used in the Christchurch rebuild due to a number of factors. However, when a building owner requires sustainability, and the material is used for its best abilities, then engineered timber systems become more feasible. At Kahukura, the timber components have been designed to be smaller, lighter and more elegant due to the use of other structural materials in combination with the timber systems."

"To manage the lateral forces, Kahukura relies on two concrete cores, and thin yet very strong steel cross-bracing. It is this combination of materials, playing to the unique strengths and properties of each, which is highly innovative and which is part of delivering a building with more sustainable content and natural materials than most in the rebuild."

Wood technology evolves

Another highly innovative design feature is the external façade (the cloak, or 'kahukura'). The structure of this has been especially designed and manufactured as cross-laminated timber (CLT) for Kahukura using sustainably grown NZ plantation lumber. It's therefore not only a carbon sink (as trees remove and store atmospheric carbon, unlike other commonly used materials) but also uses local materials rather than imported ones.

The façade was manufactured using a CLT manufacturing and construction technique – a technique quite widely used overseas but still relatively new in NZ – by XLAM in Nelson. Being a new invention especially for Kahukura, the façade structure was design reviewed by overseas experts at Jasmax's request. The timber structure is wrapped up warm in insulation and a light-weight, glass-reinforced concrete visual and rain-screen.

The timber for LVL and CLT is plantation-sourced, which makes it very renewable. Additionally, many architects like wood for the warmth it brings to the atmosphere of buildings.  

"Ara is exploring ways to meet the challenges of environmental, social and financial sustainability and developing strategies to implement solutions through the institute's operations and programme curriculum," Ara Sustainability Manager Shaun Bowler says. "With Kahukura, Ara has created a building that finds an excellent balance, as is demonstrated by the architect's use  of the Living Building Challenge principles, which is a robust environmental framework, and consequently it will save money over the 50 year projected lifetime of the building due to reduced operating costs."

"The urban design and site considerations are noteworthy in that it will sit right up against Moorhouse Ave, and make a real statement from the street. It will be a very public expression of sustainable design that invites people into Ara's city site rather than shielding the rest of the campus from the street."

Hawkins have embraced the new materials.

Steve Taw, Hawkins South Island Regional Manager, said that CLT and LVL have not caused any complications in the construction of Kahukura. In fact the materials align with Hawkins sustainability aspirations.

"Hawkins are proud to be at the cutting edge of construction by utilising renewable and sustainable materials. This aligns with our desire to reduce our carbon footprint which can only result in building better communities for future generations."

Neither does Kahukura dismiss concrete altogether. In fact, this building has significant amounts of concrete, which is also a key part of the environmental equation because it has been used to balance the internal temperature of the building and reduce sound transfer between spaces.

The building exemplifies the possibilities of sustainability in building for the students, and aligns with the sustainability course content such as the sustainable materials elective. The use of engineered wood is complemented by other sustainable features such as solar panels, high insulation, targeted passive and active ventilation, low chemical content and rainwater harvesting.