Close to home The Australian commercial building market is on a clear path towards electrification. So when it came time for an iconic property in Brisbane to decommission its gas-fired cogeneration plant, the technical expertise of the A.G. Coombs Group was called on to deliver a project close to home.
Located in one of Brisbane’s fastest growing business precincts, 540 Wickham Street is Fortitude Valley’s most prestigious commercial office address – HQ North and HQ South. Owned by Cromwell Property Group since 2011, HQ North features 29,364m² NLA over 11 storeys, including 1,086m² of retail space and secure basement parking for 330 cars.
Recently refurbished to include a bright and welcoming lobby, the building boasts outstanding environmental credentials including a 6 star Green Star v2 Office Design rating – the highest given by the Green Building Council of Australia (GBCA) – as well as 5.5 star NABERS Energy and 4 star NABERS Water ratings. Among its key tenants is A.G. Coombs Queensland, having occupied Level 1 since 2016. A.G. Coombs Advisory has worked collaboratively with the Cromwell team in the years since, with a number of projects driving improvements to the buildings’ NABERS Energy rating and sustainability performance. Recognising impending changes to the way in which NABERS Energy ratings are to be calculated, Cromwell more recently engaged A.G. Coombs Advisory to investigate the impact of the building’s 1900kVA gas-fired cogeneration plant on its environmental ratings. “Our feasibility study found the use of the cogeneration system’s absorption chiller to provide cooling as a supplement to the building’s chilled water plant did not provide significant reduction in emissions compared to the electric chiller plant, largely as a result of the auxiliary systems required to run the absorber,” says David Oakeshott, Leader – Technical Advice at A.G. Coombs Advisory. The study took into account the maintenance and life cycle of the plant, the standby power demands of the building, the changing cost of energy and a decarbonised electricity grid, in particular the upcoming changes to the NABERS Energy rating emissions factors – both short and long term. “It used to be that by using natural gas to generate power on site, carbon dioxide (CO2) emissions were approximately halved compared to the Queensland electricity grid,” says David. “But as more renewables contribute to the electricity grid, generating locally with gas is no longer as carbon efficient.”
services offered the potential to improve HQ North tower’s NABERS Energy rating to a market-leading 6 stars. The use of a HFO (R1233zd) refrigerant further reduces the Scope 1 emissions from the site. Additionally, the plant’s replacement reduces plant operational costs and allows the optimisation of plantroom space through careful design, thereby increasing the space afforded to the onsite facility management team. The use of a diesel generating set for standby power greatly simplifies the operation and maintenance of the plant and increases the reliability of the system. The sizing of the new electric chiller was critical to the success of the project. The new chiller needed to replace the absorption chiller’s capacity while still providing a high-efficiency alternative to the existing low load chiller. Accepting these recommendations, Cromwell engaged A.G. Coombs Advisory to write the specification for the
replacement of the cogeneration plant, and provide technical support to the tender process. Cromwell awarded the project to A.G. Coombs under a traditional design and construct (D&C) contract, with A.G. Coombs Advisory staying on in a technical capacity for the client. The project commenced in mid-2022 with the building’s cogeneration plant decommissioned and the system’s absorption chiller and emissions treatment system removed. A waste minimisation strategy saw many components of the plant reused, including the gas powered generator which will be used in outback Australia, the urea which is being used in another trigen plant, the lithiumbromide which is being reused in another absorption chiller overseas and various other components which are being retained as spare parts to extend the life of other plant. The absorption chiller, along with other components including redundant cable, pipework and flues were recycled. >
Net Zero ambitions The project aims to help reduce the buildings carbon emissions in 3 ways: • By not consuming gas on-site the owner is able to purchase green power from renewable sources for the operation of the site. • A significantly more efficient electric chiller was selected to replace the absorption chiller and provide low and mid load cooling which is required for about 80% of normal operation.
• A chiller using a hydrofluroolefin (HFO) refrigerant was selected. HFO has a Global Warming Potential (GWP) of one and as such is equivalent to carbon dioxide (CO2), whereas similar chillers with alternative refrigerants have a GWP of over 1400, or 1400 times that of carbon dioxide.
A.G. Coombs Advisory found that by removing the cogeneration set and replacing it with a magnetic bearing, water-cooled electric chiller and standby diesel generator to power essential Image: Ross Pottinger
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Building Efficiency
2023-2024
agcoombs.com.au