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AIRAH conference: CH2’s performance revealed

AIRAH president Dr Nathan Groenhout opening the conference

By Cameron Jewell

14 November 2013 — The energy performance of Melbourne’s iconic award-winning CH2 building has been revealed at the Australian Institute of Refrigeration, Airconditioning and Heating’s Preloved Buildings Conference at Sydney’s Doltone House.

In a presentation given by energy experts Exergy – who were enlisted to conduct a review of the building’s energy efficiency performance by the City of Melbourne – the first 6 Star Green Star building was found to be significantly underperforming.

CH2 is the City of Melbourne’s flagship building for sustainability, and features myriad technologies designed to reduce energy use, including:

  • passive chilled beam cooling
  • trigeneration
  • hydronic radiant heating
  • heat transfer and recovery between water loops
  • phase change material tanks for thermal storage
  • wind power
  • solar PV and hot water

Exergy senior consultant Matthew Hoogland told the conference that the actual energy performance of CH2 did not currently meet the high standard of its design, though works were underway to get the building up to the high standards expected of it.

The first stage of measures would provide an estimated 25 per cent reduction in energy consumption.

“We informally assessed the whole building NABERS Energy performance of the building at 4.08 stars,” Exergy’s conference paper stated.

“This represents better than average performance but is still below the building’s high potential.”

By analysing data from sub-metering systems, Exergy were able to investigate the weighting of the base building and tenancy on the whole building rating.

The NABERS tenancy rating was performing well at 5.43, however the base building rating of CH2 was a dismal 3.24, well below what would be expected for such a building.

To see what may have been causing the problem, Exergy looked at interval data for the building’s electrical utility meter, finding unusual variation in the base load over weekdays and season – a telltale sign of frequent HVAC use outside operational hours.

The key issues preventing CH2 realising its potential, the assessment found, were the strategies and commissioning of HVAC controls.

“A comprehensive revision of the strategies and commissioning of the HVAC controls was recommended to address these issues, including improved economy cycle operation, variable set points for key water and air systems, and a general tightening up of HVAC control to avoid wasteful operation,” the paper stated.

A tune-up of the physical components of the system was also recommended.

The building is expected to achieve a 4.5 star NABERS base building rating (compared with current 3) with the measures currently intended for implementation, with further improvement expected with intensive monitoring and tuning.

There have been numerous criticisms of CH2, with some technologies, such as the wind turbines, not performing as expected. However, at the time of construction, the technologies employed by the building were very uncommon, and it was designed as a “showcase” of sustainable building features that could be used as a model for others to learn from.

There was a lot of good news to come out of the AIRAH conference, too, the theme of which was “preloved building reloved”. As AIRAH president Dr Nathan Groenhout said, it was about “moving forward with the relationships we have with our buildings”.

Keynote speakers included architect Professor Robert Morris-Nunn of Circa Morris-Nunn Architects, whose understanding of Tasmania’s rich history had informed his company’s extensive revitalisation work, and Brookfield Johnson Controls’ Jon McCormick.

Sustainable Melbourne Fund’s Scott Bocksay kept the crowd up-to-date on the environmental upgrade agreement story, while NDY’s Chris Nunn, WSP Built Ecology’s Brenda Kingston and JHA Consulting Engineers’ Robert Armitage were part of an interesting panel session looking at the successes and difficulties of some high-profile upgrades.

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