Iain Stewart

Exergenics' plant optimisation

Founder, Exergenics; Master of Environmental Engineering, University of Melbourne

Conventional chilled plant control strategies for buildings are generally inefficient in delivering cold water to air handling units, wasting energy, increasing peak demand and increasing energy costs.

Typically, chiller staging depends on the return temperature of water fl owing through the chilled water loop. This method ensures adequate chilled water is delivered through the building for cooling; however, it only uses a fraction of the available data in a modern chilled plant room.

Exergenics founder Iain Stewart developed a new method to control plant equipment that addresses these inefficiencies, ensuring that plants can run at optimal efficiency under all conditions.

Stewart’s method involves collecting data from the existing building management system to train a machine-learning system that represents chillers, pumps and cooling towers.
These algorithms are then combined to develop a digital twin — a mathematical representation of a physical system — of the entire chilled plant room.

Compared to conventional strategies, Stewart’s method reduces energy and peak demand by 10 to 20 per cent.

This model gives engineers the ability to simulate water delivery, given the ambient weather conditions and loading of each piece of equipment.

The process is then reversed and an optimisation algorithm is used to determine ideal loading for all weather conditions and thermal loads. The outputs of this modelling form the basis for the new, optimal control strategy.

Compared to conventional strategies, Stewart’s method reduces energy and peak demand by 10 to 20 per cent.

If the method were applied to a large office building that uses grid electricity, the associated emissions reduction could be as high as 35,000 kg of carbon dioxide per year.

Judges’ comments:

“This project presents an approach for a multivariate model to improve the efficiency of chilled water supply for building climate control by creating a digital twin of the chilled plant room. This requires systems thinking and engineering judgement. The real power of the digital twin is the ability to optimise overall operation under a variety of weather conditions.

“As a result, there are environmental benefits and real savings for the organisation. The algorithms used and the way in which these provide the opportunity to save energy reduce costs in pumping chilled water. The benefits to the building owners and the community more broadly are potentially very substantial.”

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