One of New Zealand’s leading architects Warren and Mahoney (W+M) has designed the country’s largest mass timber building, and it comes with a view to reducing embodied carbon.
Simon Topliss, principal in W+M’s Australian arm and a timber expert, says the 10,000 square metre building at 90 Devonport Road in Tauranga, New Zealand is on its way to becoming a “timber hero” with carbon reduced to its “lowest possible point”.
Development and investment company Willis Bond commissioned the building for lead tenant Tauranga City Council, which has signed a 15 year lease.
For the stakeholders the building demonstrates a shift in values around timber as a desirable architectural choice.
It features rainwater harvesting, electric vehicle charging stations and end of trip facilities for active transport. And it’s targeting the highest 6 Green Star Design and As-Built NZv1.0 Design Review Rating.
“Anyone who is designing now who isn’t factoring embodied carbon as a key design consideration, will be left behind”
While the columns and beams in the building are all laminated veneer lumber (LVL) timber, the floor and lift core panels are cross-laminated timber (CLT). The building incorporates some steel bracing elements performing lateral load functions.
Tauranga Commission chair Anne Tolley said the concept for the Tauranga building was to “push the boundaries” on a sustainable workplace that “maximises the use of natural materials”.
“This will be our home for at least the duration of the 15 year lease, so it’s important that we get it right and create a facility that both speaks to its Tauranga Moana origins and provides a welcoming and people-friendly space for our staff and the community,” she said.
“Willis Bond and Council staff continue to work with mana whenua [the authority of a Maori tribe over an area of land] to ensure that Matauranga Maori [Maori knowledge systems] principles are incorporated throughout the design process.”
The big shift
Speaking from the Melbourne office, mass timber expert Topliss, who heads the studio’s education sector team, told The Fifth Estate that in his previous role he made his first foray into mass timber with Monash University’s Gillies Hall student accommodation, completed in 2019. The project was also the first full mass timber structure for builder Multiplex, with the use of CLT reportedly substantially reducing the embodied carbon in the building relative to a concrete structure.
Embodied carbon is carbon emitted through the manufacturing, transportation and installation of building materials and components.
Simon also helped deliver the $100 million student apartments for La Trobe University the same year. This mass engineered timber construction project brought CLT further into the mainstream in a way that had never been done before.
He says these formative projects “changed the conversation around how we build, how we can do better, and make sustainability conspicuous – not just photovoltaics on a roof”.
“This will be our home for at least the duration of the 15 year lease, so it’s important that we get it right”
Awareness around embodied carbon is now exploding into the mainstream.
“Anyone who is designing now who isn’t factoring embodied carbon as a key design consideration, will be left behind,” Topliss says. “Knowledge is changing faster than buildings can be built.
“We’ve seen a big and exciting shift in the last five years. Tackling embodied carbon… is now central to the aspirations of the project and increasingly clients feel a responsibility to put it front and centre.
“Buildings… need to exceed expectations to maintain relevance. That’s quite a big shift.”
In response to this growing appetite the company recently held a roundtable discussion in its Auckland office, with Topliss moderating the conversation and Divya Purushotham, associate principal and architect in Auckland, contributing her insights.
There’s a lot to learn for professionals and developers alike, regardless of the angle they approach the deployment of mass timber construction.
Purushotham told The Fifth Estate that New Zealand looked to Australia for insights into timber, and that knowledge-sharing was imperative to mitigate the risks associated with supply chain procurement and to navigate engagement with developers.
Setting a carbon budget
In an interesting twist on business as usual for architects, W+M does not operate with a traditional architectural approach, where the design comes first and the sustainability outcomes come later. This design studio sets a carbon budget before the project design is even started – and then designs around this.
“Make the decisions earlier,” Topliss advises. “That’s when the biggest impact happens: when we establish that brief it has a big impact on carbon outcomes of projects.”
Architects are working in a market that’s only now starting to understand and respond to the challenge of measuring and reducing carbon in construction.
In new projects, about 75 per cent of carbon emissions comes from the superstructure of new buildings – so “the best way to reduce embodied carbon is to use what we already have through adaptive re-use, and [to ensure] our building stock will still be here in years to come”.
The second-best way is timber.
“Mass timber retains carbon when compared to its steel and concrete equivalent, making it a more favourable construction material with regards to carbon emissions,” Purushotham says.
From the biggest to the “unsexy middle”
The Tauranga project promises to be New Zealand’s largest mass timber office building. As it is designed for a local government authority, the architects, developers and tenants alike sensed an opportunity to demonstrate a clear shift in the perceived value of the material to the mainstream.
There is a “premium perceived to be associated with sustainability”
There is a “premium perceived to be associated with sustainability,” Purushotham notes.
But while 90 Devonport Road may be the largest mass timber building New Zealand has seen so far, Topliss says that’s not what should be making headlines.
What should be making headlines, he says, is the need to focus on transitioning mainstream projects.
“There’s a shift we need to make in the industry to concentrate on the middle. Everyone’s trying to do the biggest and the best. How do we adapt the unsexy middle?
“We’re seeing the industry mature – [here timber is being used in] an elegant commercial building, when it could have been a standard structure.”
The challenges of designing with timber
Timber requires a different approach to traditional procurement, and requires well-informed design teams that have experience with this technology. Attention also needs to be paid to emerging regulatory frameworks, the pair tell us.
Purushotham told The Fifth Estate that there is a “general nervousness” around mass timber because of the lack of precedent. In order to demonstrate a benchmark for timber construction in NZ, it was important to simplify the design and retain familiarity in materials and buildability where possible.
From procurement, fire performance, acoustics, grid, compliance to cost, there will be challenges and constraints when designing with timber – some real, some misconceptions, Puruthotham says.
“These are the challenges in the fine level of detail”.
“90 Devonport Road benefited heavily from a group of consultants all coming together to challenge and innovate business-as-usual construction norms, and this is exactly what designing with timber requires.”
“Everyone wants to do better… and we need to collectively be willing to take a risk.”
A building designed for a unique environment
New Zealand is well-known for being in the firing line for a completely unavoidable natural phenomenon – earthquakes.
This can be a disaster if not prepared adequately – as we saw in the devastating Christchurch earthquake in 2011 which caused extensive damage to infrastructure and buildings.
So in NZ, regulations dictate that buildings must be seismically resilient. In this building, and within the parameters of mass timber construction, that means having allowances for deflections between floors – a gap so that the building has some give safely in the event of an earthquake, without buckling under the pressure.
To those of us on the other side of the ditch, this all sounds terrifying – but to NZ architects this kind of thinking is just part of their everyday.