Sydney HVAC comparison

New comparisons in commercial HVAC systems

The ARBS Education and Research Foundation has released the results of a comparative study conducted on HVAC systems in commercial buildings.

The research and the resulting report – touted as a world first on air distribution systems – was conducted in Sydney by Team Catalyst.

“There are few surprises for experienced HVAC engineers who understand the complexity of these systems,” says PC Thomas, director of Team Catalyst. “There are, however, many lessons around the interaction of the different system loops for larger centralised HVAC systems, the most important one being that careful consideration needs to be given in the selection for a fit for purpose HVAC system.”

ARBS and Team Catalyst say they approached the study not to determine a superior system but instead to compare their operational outcomes.

The specific readings are meant to serve as a starting point for those wishing to explore alternative air distribution systems within commercial buildings. The findings can help to inform engineers and technical staff on the actual operations of HVAC systems, specifically regarding efficiency and energy costs.

“The focus on greening buildings in the past few years has led to discussions of the pros and cons of various HVAC systems,” says Thomas, pointing to increased considerations on reducing emissions and improving comfort.

Interested in how these configurations ran, Team Catalyst conducted simulated tests of the three most prevalent HVAC systems in Australia’s commercial buildings: passive chilled beam, underfloor air distribution, and variable air volume.

From these three HVAC system configurations, the research points to predicted performance while establishing a framework for their variations and combinations.

Thomas notes the impact that climate change may have as systems react differently to variables such as humidity and weather.

“Team Catalyst approached the study by carefully modelling a typical configuration of each of these systems, as installed in the same building envelope, with the changes required to represent a practical installation,” he says. “It must be noted, and re-iterated, that many potential configurations and combinations of these systems are possible, and the results would change for each.”

The study avoids encouraging or discouraging the use of a specific system. Instead, it is a reference point of objective criteria for engineers to involve alongside their technical, physical, financial and/or perception constraints.

“Using data from the simulation of a typical 10-storey commercial building in Sydney, the study provides predicted energy intensity for each of the three systems,” says Ashak Nathwani, Stud.AIRAH, ARBS Foundation board member. “Specific readings are likely to vary a little at other locations, but the findings of the study provide an important starting point for analysis and decision-making.”

The research points to the ongoing need to ensure right sizing of HVAC equipment for buildings and the importance of considering an overall control strategy for all system loops.

It also identifies the need to close the knowledge gap between designers and operators of HVAC systems. Often installations can be oversized, resulting in equipment not operating at peak efficiencies.The report says this is particularly true for central chilled water plants.

“Efficiency and comfort can be delivered by any appropriate, modern HVAC system, provided the design concept is well thought through,” says Thomas. “A simple, robust design, with a clearly defined control strategy will trump a complex system for operational performance every time.”

To view the full report and its findings, click here.

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