Pita Te Hori development is one of New Zealand’s most sustainable office precincts

After Christchurch experienced devastating earthquakes in 2010 and 2011, public consultation indicated a district energy scheme was desirable as part of the city’s rebuild. The KEB Pita Te Hori District Energy Scheme is the first private investment in such a scheme in New Zealand.

Ngāi Tahu Property, the property development arm of Ngāi Tahu iwi, approached Aurecon with their vision to create a flagship development in the heart of Christchurch CBD. Aurecon provided structural and mechanical engineering services for the development, proposing the idea of an innovative commercial District Energy Scheme (DES).

The DES solution is a high-quality, efficient and cost-effective centralised energy supply solution to replace traditional distributed building services systems for an entire city block.

A vision of the future, built on the values of the past

Initially contracted to design independent buildings, Aurecon saw an opportunity to do something profoundly different, aligning to some of the iwi’s core values of stewardship and sustainability, and proposed the idea of a district energy scheme to them. Aurecon showed Ngāi Tahu Property how they could secure their energy future with long-term maintenance and energy cost savings, as well as contribute to a sustainable future for the wider community.

Imagined and delivered by Aurecon’s Christchurch building services team, the DES solution was brought to life at a thought leadership event, where Aurecon helped Ngāi Tahu Property to reimagine the development’s (and the city of Christchurch’s) energy future.

At the forefront of sustainable development

The use of the natural resources was a key consideration on the project.

The Aurecon team quickly identified an abundance of water flowing below the site in the form of aquifers, ranging in depth from 30 m to 140 m. While yet to be extracted, the bountiful supply of clean fresh water, deep underground at a perfect temperature, proved the ideal source for harvesting energy.

While a ground-source heat pump solution was not a new idea for Christchurch, the scale of the project was, as the DES would ultimately be supplying energy to six buildings.

Resilience and environmental sustainability

The DES is extremely resilient and has significant community and cultural benefits, specifically in adhering to the Ngāi Tahu Property core value of working actively to protect the people, environment, and resources, while providing an energy-efficient solution that can be emulated across the Christchurch CBD and throughout New Zealand.

The energy scheme boasts a number of sustainability benefits, including:

• Using a 15 000L thermal store to even out the load profile, reducing the need to rely on thermal electricity generation plants during peak periods
• Using over 75% hydroelectricity
• A global efficiency of over 700% (Coefficient of Performance rating (COP) 7.1)
• Saving 215 000 kWh of energy per annum when compared to conventional systems
• Transferring waste heat and cold from adjacent buildings 

Other Pita Te Hori sustainability interventions include:

• The Iwikau building at 93 Cambridge Terrace is base-isolated, with triple friction pendulum bearings located on top of the ground floor columns. This results in reduced floor accelerations for the building above the isolation plane, which then equates to reduced damage to the structure, as well as the building fit-out and contents.
• Office buildings within the development make use of seismic monitoring and real-time reporting systems, which monitor accelerations and allow for more accurate building performance assessments.
• Heat is used from the Council office’s tri-generation plant which is powered from waste landfill gas.

“Working with [the Aurecon team] has been an incredible experience. The idea of a DES was brought to us in response to our core values, and has helped us to stay at the forefront of sustainable development in the city,” said Gordon Craig, Senior Development Manager, Ngāi Tahu Property.

The project received two Property Council New Zealand Excellence Awards in the Commercial Office and Green Building categories, and is also the new home of Aurecon in Christchurch. The use of the innovative DES with ground source heating and cooling allows for much greater future longevity and control/comfort, and positions the Pita Te Hori development as one of New Zealand’s most sustainable office precincts.