An artist’s impression of Mirvac’s new Perth office

16 October 2013 — Mirvac’s new 33-storey office tower at the Cathedral + Treasury Precinct Area will host Perth CBD’s first trigeneration plant.

Mirvac joined with Perth-based Kerry Hill Architects for the project, which is targeting a 4.5-star NABERS rating and has a 5 Star Green Star Office Design v3 rating.

Environmentally sustainable building features include improved energy performance, high indoor environmental quality, promotion of sustainable transport and provision of secure bike storage, construction waste recycling and water efficiency.

Mirvac development director Dean Mudford said the gas-fired trigeneration system would provide an environmentally sustainable method of generating electricity, heat and cooling.

“Significant savings in potable water use and sewage discharge will be achieved through a greywater recycling plant, which supplies water for landscape irrigation and toilet flushing by treating waste water from hand basins and end-of-trip shower facilities,” he said.

The project includes an outdoor civic space with collaboration among prominent artists contributing to the design and highlighting the cultural and historic significance of the site.

The office tower is scheduled for completion in 2015 with co-owners Mirvac and Keppel REIT then receiving a 99-year ground lease from WA’s state government.

The building has a net lettable area of about 30,600 square metres with 98 per cent pre-committed under a sublease to the state government.

A Mirvac spokesperson said the trigeneration system at the Mirvac office tower would include low-carbon electrical power generation, absorption type chilled water generation and water heating from using the waste heat from the electrical power generation process and the gas fired generator.

The power, heating and cooling will be distributed and used across the Mirvac office tower and the adjacent Treasury Buildings.

They said significant reductions in carbon emissions will result from:

  • Generating electricity using a lower carbon intensity fuel compared to traditional coal-fired generation
  • Being able to harness the ‘waste’ heat from the process to heat water and through and absorption chiller, provide space cooling.

The spokesperson said significant savings in energy and carbon emissions would be achieved by the Mirvac office tower.  “Based on preliminary computer modelling results, savings of approximately 60 per cent are expected compared to the current average base-building NABERS rated stock in Perth.”

The spokesperson said in the construction of the Mirvac office tower, the company had have focused on choosing materials that would have the least impact on the environment and provide high indoor environment quality for occupancy health and comfort. The design and construction process encourage the reduction in the amount of materials used, reuse of building materials and the use of recycled and recyclable materials wherever possible.

Initiatives included:

  • The reduction of embodied energy and resource depletion is recognised through reduced use of cement in concrete
  • All structural and reinforcing steel is sourced from a responsible steel manufacturer
  • The building products for major services meet the Best Practice Guidelines for PVC in the built environment
  • The timber used is either reused or sourced from certified environmentally responsible forest sources
  • The building design minimises the embodied energy and resources associated with demolition.

In the area of indoor environment quality, the building design and materials selection include:

  • The ventilation system increases the amount of fresh outside air delivered to occupants by 150 per cent compared to the statutory requirement of 7.5 litres per second per person
  • Carbon dioxide levels are monitored so that the building services vary outside airflow  rates to achieved comfort condition whilst saving power when the building is only partly occupied
  • The building design provides good levels of daylight for building users
  • The building is designed to reduce the discomfort of glare from direct sunlight
  • A large proportion of the office areas have long distance external views to reduce eyestrain
  • Thermal comfort levels have been modelled and assessed during the design process to optimise occupant comfort
  • Low-voc paints, carpets and sealants have been used
  • Low-formaldehyde composite wood products, that is MDF board,  have been used
  • A dedicated tenant exhaust riser is provided so that indoor pollutants can be removed from printing and photocopy areas

Potable water savings of about 50 per cent have been calculated for the Mirvac office tower. The benchmark was created using Green Star Office-Design v3 calculation framework utilising current standard design practices and standard WELS rated fittings,” the spokesperson said.

Mirvac has a long history of sustainability leadership dating back to the first solar suburb at Newington for the Olympic Village in 2000 and subsequent achievements since. Sustainability is core to Mirvac’s ongoing success and is built into everything we do.

“Since its inception, sustainability has been top of mind at Mirvac’s office tower in the Cathedral + Treasury Precinct. With targets such as Green Star and NABERS Energy identified early in the design process, a team of specialists, including a Green Star accredited professional and Mirvac asset management expert, was formed to deliver on our joint government of Western Australia and Mirvac vision.”