Digital twin cuts costs & emissions at Te Rua archive

Dexus says data from the Te Rua National Archives project shows digital twin technology reduced contingency spending and cut building emissions. The approach was used on the Government's NZD $290 million archive development in Wellington.

The figures come from Te Rua, a highly specialised national archive designed to remain operational after a one-in-1,800-year earthquake and maintain tight temperature and humidity controls during a prolonged power outage. Those requirements made conventional construction methods too risky for a project holding taonga and government records under UNESCO Memory of the World obligations.

A three-dimensional digital model allowed architects, engineers and contractors to identify and resolve design clashes before construction began. Project data shows this kept contingency spending at 5% on Te Rua, compared with an industry norm of up to 10%.

A clash occurs when different building elements are designed to occupy the same space, creating problems that may only become apparent on site. In large projects, these errors can lead to redesigns, delays and extra costs when contractors find that beams, services or mechanical systems cannot be installed as drawn.

According to Dexus, the Te Rua model was clash-free at tender stage, a level of accuracy it described as unprecedented in complex civic construction in New Zealand. Contractors used site stations linked to the live design model to position services with millimetre accuracy, while augmented reality tools were used to check installations during the build.

Operational model

After construction, the digital twin became a facilities management system. More than 20,000 assets were embedded in the operational model, giving building managers real-time information on temperature, humidity, energy use and structural movement.

Dexus says operational use of the system has already cut the building's carbon emissions by 80%, equivalent to about 1,330 tonnes, through monitoring and tighter control of environmental systems. The model can also simulate full or partial power failures, test generator performance and monitor structural movement through accelerometers.

"When you are managing irreplaceable taonga and national records, there is no margin for error. Any design flaw that affects temperature, humidity or structural performance directly threatens the integrity of the collection, so we needed absolute certainty that every element of the building would perform exactly as intended, not just on day one but for decades to come," said Phill Stanley, Portfolio Manager, Dexus.

Stanley said the data pointed to wider implications for New Zealand's broader infrastructure pipeline, which Dexus puts at NZD $275 billion. He said using digital twins from the design stage could help avoid cost overruns across major projects if similar results were replicated elsewhere.

Hospital use

Dexus says the method could also be relevant to hospitals, data centres, water storage facilities and civic buildings. Stanley said healthcare projects were particularly well suited to digital twins because of their dense service requirements, reliance on uninterrupted power and need for strict environmental control.

"This really does lift the bar in a way we have not seen before. It shows what is possible when everything is coordinated from day one. The scale of the model and the accuracy behind it are unlike anything we have worked with in New Zealand. For us, it gave a level of design certainty you just do not get on projects of this complexity.

"The technology has clear applications across New Zealand's planned healthcare infrastructure spend.

"The next generation of hospitals, including the new Dunedin Hospital, the redevelopment of Nelson Hospital, the expansion of Wellington's Emergency Department and major upgrades across Auckland's hospital network, will all require the same level of coordination and environmental performance delivered at Te Rua.

"These facilities rely on uninterrupted power, complex mechanical systems and precise climate control, and even minor faults can create clinical risk.

"Digital twins could help control costs, reduce construction delays and ensure clinical spaces meet strict operational and environmental requirements from the day they open," Stanley said.

He also said timing matters. The benefits depend on decisions made at the earliest design stage, before projects move into procurement and construction.

"You cannot retrofit this level of coordination. You have to make the decision right at the start or you lose the opportunity. Once you commit early, everything else becomes more predictable," Stanley said.

Dexus also pointed to the next stage of development, with artificial intelligence expected to be integrated into the system so it can detect changes in performance and suggest interventions before faults emerge.

"Systems will be able to flag components that are likely to fail months in advance, automatically adjust environmental settings to reduce energy waste and analyse seismic or structural data to identify early signs of stress that are invisible to the human eye," Stanley said.

Nik Kemp, Executive General Manager for Growth Markets at Dexus, said the archive was delivered in partnership with the Government and under tight budget constraints.

"From the outset we knew that cost certainty was non-negotiable. When you are delivering a project of this complexity on behalf of the Government, the risk profile is significant and the tolerance for cost drift is very low. The digital twin gave us the visibility we needed to keep the budget stable while still meeting seismic, cultural and archival performance requirements that were unlike anything attempted in New Zealand. It allowed us to manage risk in a disciplined way and give the Government confidence that the project would be delivered exactly as promised.

"For anyone delivering civic infrastructure, this kind of approach is fast becoming essential. It gives you real clarity on design and cost, and confidence that the finished asset will perform the way it needs to. My view is that this will become the gold standard for major projects. At its heart, it is not just about better buildings. It is about better collaboration and better relationships," Kemp said.