Diamonds are Forever

December 4 2020

We have made a commitment to keep our practice in line with New Zealand’s own pledge to become a carbon-zero country by 2050.

When it comes to a carbon footprint, the construction industry is too big for its boots. Far too often, building does not touch the land lightly. At RTA Studio we don’t just pay lip-service to the idea of sustainability: we have made a commitment to keep our practice in line with New Zealand’s own pledge (biogenic methane aside) to become a carbon-zero country by 2050.

It’s a fine aspiration but it won’t just happen by wishful thinking: like any goal, it needs real-time stepping stones to succeed. What does it mean to be on the sustainability pathway? Well, the way we see it, as a business we need to produce 33 per cent less carbon every decade. That’s why we have signed up to the Toitū Envirocare certification programme, a consultancy that follows international best practice and allows us to analyse and audit the volume of greenhouses gases the practice produces over a 12-month period, with the goal of becoming Carbon Zero by March 2021.

In the day to day, that means we are tracking our petrol consumption, how many flights we take, recycling what we can. Initially we realise that, despite these mitigations, we’ll need to invest in carbon credits to keep us below our self-imposed limits. But the aim is to make those strategic decisions that bring us closer to the goal. Already we have changed the way we operate with more site visits hosted by Zoom (a Covid-19 silver lining for the planet). And our sights are set on swapping to electric vehicles once the current leases run out.

Of course, that’s only one aspect of how we can influence a more sustainable future. The projects we design – from commercial through public to educational and residential – have a bigger impact. According to the NZ Green Building Council, New Zealand’s built environment is responsible for 20 per cent of the country’s carbon footprint. At RTA, we have a long tried to make more planet-friendly outcomes. Ten years ago, we embarked on a mission to design a four-bedroom home that was carbon zero to build, run and demolish. The project won the Future House category of the World Architecture Festival 2012 and although the C3 house has not been constructed, we hope that one day it will be.

While our focus is on seeking out likeminded clients where sustainability is a desired outcome – easy to say but often hard to put into practice – the stars aligned when RTA Studio, in collaboration with Irving Smith Architects, was commissioned to reimagine the Rotorua headquarters of Scion. This Crown Research Institute specialises in technology development for the forestry industry and sits on the edge of a redwood forest. In other words – the perfect client for a sustainably driven design programme.

The plan was to bring the workforce, previously siloed in smaller buildings dotted around the campus, into a central innovation hub. Creating a public interface for local tourism was also key. The 1800 square metre ‘Te Whare Nui o Tuteata’ facility is a cutting-edge showcase for engineered timber not only in terms of the aesthetic but what it contributes to a carbon-zero future. A trio of ‘peaks’ in gluelam timber, representative of the three hapu in the region, stand proud and tall at the entrance. These are decorated with a CNC-milled motif designed by local artist Grant Marunui.

Visitors pass beneath these portals to a double-height atrium where a curated exhibition of wood-fibre technology and a café welcomes the public. Immediately impressive is the diagrid which rises three storeys to form the skeleton of the building. These structural elements are made of high-performing Laminated Veneer Lumber, a straight and durable product known to have fire-resistant characteristics. The technology developed around the X-shaped intersections is worth a special mention. Where normally a steel node would be employed, the client requested a timber solution. Dovetail joints slot and glue together in a beautiful expression of craftsmanship and the only steel included in the structure are the seismic fuses required for earthquake mitigation and a steel footer which connects the V-base of the diagrid to the floor.

Other timber products used in this wharenui named after Tuteata, an ancestor of the three local subtribes, include the suspended subfloor on the ground level which was precisely engineered in cross laminated timber and covered with cork tiles. Above in the open-plan office spaces which are not glazed off from the public areas below, recycled carpet was used on a timber floor structure. For good measure, a timber ceiling offers superb acoustic performance.

Another feature that differentiates this building in both form and function is the striking curtain-wall façade with decorative frit glass. A granulated pattern features three different porosities and is expressed in colours that reflect the deciduous and evergreen species of the surrounding forest. The frit is a climate modifier which works to provide shade and reduce glare and the double-skin façade contains a thermal gap which preheats air in winter to reduce the load on the heating system. In summer, ventilation flaps can be opened for airflow while in the shoulder seasons, the building operates passively without the need for mechanical heating/cooling intervention.

To see how we fared in terms of impact on the planet, RTA had the building assessed by eTool which measured its carbon performance against an international benchmark. Without getting too technical, the results were pretty darn astounding. At time of completion, the Scion hub had already achieved embodied carbon zero. Furthermore, to measure all of life and end of life carbon, the eTool system used the target set by the RIBA (Royal Institute of British Architects) for buildings to meet by 2030. This is set at 500kg of carbon/ msq over a 60-year life span and includes embodied carbon, operational carbon and carbon release when materials are demolished without recycling, eg incinerated or sent to landfill. It was assessed that Scion already meets that 500kg of carbon/ msq standard – no need to wait 10 years!

That the hub was constructed at comparable cost to one using more conventional materials and methods (with steel framing and concrete flooring) is just the icing on the cake. At RTA, we think the evidence is clear. By keeping a green eye on how we do business at the office, using engineered products made from sustainably grown pine and putting more thought into the operational characteristics of a building, we can significantly contribute to New Zealand’s carbon-zero future. Embracing such ideas, we hope to be able to toss away our clumsy clodhoppers and leave a much lighter footprint on the land.