Rethinking cooling strategies for Australian data centres

Australia’s climate is heavily influenced by El Niño and La Niña events. This sees a swing in Australia’s climate every 3-7 years and can last anywhere from 6 months to 2 years. La Niña promotes above-average rainfall and cooler temperatures in eastern Australia, while El Niño increases the likelihood of hot and dry conditions in Australia.

Other options: Heat reuse and seawater

Alternative strategies that have grown in popularity are waste heat recovery systems and the use of seawater for cooling. We’ve seen this increasingly used in areas in Europe.

Waste heat recovery is one option. This involves capturing and repurposing heat from IT equipment and redirecting it to nearby facilities or district heating networks. In Denmark, a hyperscale operator partnered with an energy service company to feed 165,000MWh of heat annually to a public heating system using heat pumps. This blueprint is impressive and attractive to operators looking to reduce costs but only works when stakeholders and infrastructure are aligned.

In Australia, some sites are well-positioned to take advantage of natural advantages like access to seawater or river water cooling. These systems use natural cold bodies of water to reduce reliance on energy-intensive compressors. This offers sustainability benefits; however, long-term viability and seasonality need to be assessed during the design period through modelling.

After all, the iconic Sydney Opera House is cooled using seawater taken directly from the harbour. The system circulates cold water from the harbour through 35 kilometres of pipes to power both the heating and air conditioning in the building.

Rethinking metrics

PUE has been the default metric for data centres, determining efficiency. The trouble is, this has its own limitations, particularly when looking at different regions and facilities.

Water usage effectiveness (WUE) has been pushed to offer a different metric that measures the water consumed per unit of IT power. However, this too can be distorted by the local climate and system choices. In turn, this makes comparing facilities in different regions harder as it’s not apples to apples. WUE also fails to account for the water used in power generation, so there is a hidden cost to the consumption measurements.

The other option is carbon usage effectiveness (CUE), which looks at the carbon intensity of both water and electricity. By looking at both in the same equations, we can get a more holistic view of the data centre’s efficiency and better identify the trade-off between power and water for cooling.

No one fit

Global colocation providers often rely on reference designs. These are standardised templates that can be adapted to bring similar data centres to new regions. However, while this saves time, applying the same cooling systems can lead to inefficiencies, high costs or project failures.

Understanding the impact that local conditions like the carbon intensity of the grid or the accessibility of water should be the factors that drive the design choices. To do so effectively requires an engineering team with expertise in multi-disciplinary projects so that they can work together to find solutions.

The National Australian Built Environment Rating System (NABERS) for data centres measures their energy efficiency and environmental performance to provide a star rating from one to six. Unlike design-based assessments, NABERS ratings are based on operational data to offer an accurate reflection of how efficiently a facility runs.

Overall, when bringing a reference design to Australia, choosing whether to use water or power for cooling largely depends on the type and location of the facility. Australia is so large and varies across seasons that when bringing reference designs to the region, they need to be even more localised, both in overall and cooling design.