30 | Plant & Works Engineering www.pwemag.co.uk June/July 2026 Energy & Environmental Management Focus on: Cooling Data centres are the invisible engines of the digital economy. Every streamed video, cloud transaction and artificial intelligence (AI) query relies on racks of servers running continuously, generating vast amounts of heat in the process. According to the International Energy Agency (IEA), data centres could consume up to three per cent of global electricity demand by 2030, driven largely by AI workloads and high-performance computing growth. At the same time, while data centres enable digital innovation, their escalating energy demand presents a growing sustainability paradox that should not be ignored. Traditionally, air cooling has been the default approach for data centres. However, higher rack densities and AI-driven processing loads are pushing air systems to their physical limits. Cooling already accounts for a substantial share of total power draw, typically representing 30–40 per cent of a data centre’s electricity consumption according to the World Economic Forum (WEF). This is second only to the IT equipment itself. The resource implications extend beyond electricity. For instance, a Washington Post analysis highlighted that generating a single 100-word email using generative AI can require the equivalent of a bottle of water to manage server temperatures. This illustrates the hidden water footprint behind digital services. As demand accelerates, these inefficiencies compound. More energy in means more heat out. Unless cooling approaches evolve, operators risk rising PUE (Power Usage Effectiveness) ratios, increased downtime exposure, and growing scrutiny from regulators and investors alike. Liquid cooling moves from niche to necessity Against this backdrop, liquid cooling, including direct-to-chip systems that cool components via cold plates and immersion methods that submerge servers in coolant, are gaining momentum. Liquids transfer heat far more efficiently than air, which allows systems to maintain stable temperatures even under extreme computational loads. This efficiency shift has material benefits. Reduced reliance on fans and chillers cuts energy use, while tighter thermal control helps extend server lifespan and improve reliability. From an environmental, social and governance (ESG) perspective, liquid cooling also opens the door to heat recovery, transforming waste heat from a liability into a potential asset. The study ‘Data center waste heat for district heating networks: A review,’ published in the Renewable and Sustainable Energy Reviews journal suggests that recovered data centre heat could meet up to ten per cent of Europe’s heating demand by 2030, if effectively captured and reused. Nordic countries are already demonstrating what is possible, with large-scale projects supplying district heating networks using recovered data centre heat. The opportunity of heat reuse Reusing waste heat is not a silver bullet, but it represents a meaningful step toward balancing digital growth with climate responsibility. Indeed, the WEF’s Artificial Intelligence’s Energy Paradox report notes that redirecting data centre heat is a “crucial step” in managing AI’s environmental impact, even though it must sit alongside broader efficiency measures. However, heat reuse only works if thermal systems are designed and maintained correctly. Cooling fluids must remain thermally stable, pumpable and uncontaminated to ensure consistent heat transfer. Poor fluid condition undermines efficiency, accelerates equipment wear and increases the likelihood of unplanned shutdowns — outcomes no data centre can afford. Reducing energy waste in data centres Let’s consider the example of a mid-scale European data centre that supports cloud and AI workloads. The facility operates high-density racks with an increasing proportion of liquid-cooled infrastructure. While the data centre invests heavily in electrical resilience and server efficiency, thermal fluid condition is monitored only intermittently, with maintenance triggered reactively by alarms or declining performance. As processing demand intensifies, heat loads rise and cooling efficiency begins to drift. Pump energy consumption increases, PUE trends upward, and engineers identify early signs of fluid degradation during Clive Jones, managing director at thermal fluid supplier and lifecycle management specialist Global Heat Transfer, explains why, as global data volumes surge, the challenge of keeping these facilities cool, reliable and sustainable has become one of the sector’s defining issues. Why data centre cooling is now business-critical
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