Data centre cooling in the AI era
Author: Joe Peck
During a busy Data Centre World London 2026, Joe from DCNN caught up with Alistair Barnes (pictured above), Global Head of Mechanical Engineering at Colt DCS, to ask how the mechanical engineering discipline is evolving in response to the rapid rise of AI workloads.
The two discussed a variety of topics, from the shift towards liquid cooling solutions to the challenge of keeping pace with ever-increasing rack-level power densities.
Here, you can read the full Q&A, in which Alistair shares his perspective on where liquid cooling stands today, how Colt DCS’s Global Reference Design philosophy shapes its approach to data centre infrastructure, and what he believes remains the industry’s toughest unsolved engineering challenge:
Liquid cooling, rack densities, and the future of mechanical engineering
Joe: Hi, Alistair! So, how is mechanical engineering keeping pace with the shift to higher-density AI workloads?
Alistair: Mechanical engineers are keeping pace with higher‑density AI workloads by moving beyond traditional air‑only cooling and rethinking the entire thermal design stack. Instead of simply supplying cold air, they now operate more like system integrators, collaborating closely with IT and facilities teams to cool heat‑intensive components such as GPUs. This includes integrating direct‑to‑chip cold plates, liquid distribution loops, and hybrid cooling systems capable of managing the extreme heat generated by modern AI hardware.
Joe: In your opinion, is liquid cooling now a mainstream solution or still a specialist one?
Alistair: Liquid cooling is becoming increasingly mainstream, but the industry isn’t yet at a point where it can rely on liquid alone, as air still plays an important role in most deployments. Operators adopting Global Reference Designs (GRDs) now include liquid‑cooling options to support high‑density AI workloads that air alone can’t efficiently manage. As a result, many still use hybrid setups that combine air cooling with liquid where needed. Closed‑loop systems, such as liquid‑to‑chip, circulate coolant in a sealed loop, ensuring near‑zero wastewater and making them practical and sustainable.
Joe: Where does mechanical engineering sit in Colt DCS’s broader data centre design philosophy?
Alistair: Mechanical engineering sits at the core of our design philosophy, supporting our commitment to delivering scalable, efficient, and sustainable data centre solutions. We adopt a GRD, a standardised and repeatable blueprint that accelerates deployment, optimises cost, and maintains consistent quality while remaining flexible enough to meet local requirements. Mechanical engineers play a key role in shaping the GRD, ensuring mission-critical cooling infrastructure and integrating new technologies across sites to support future growth and reliable operations.
Joe: What’s the hardest engineering problem the industry hasn’t solved yet?
Alistair: The hardest engineering problem the industry hasn’t solved is keeping pace with the accelerating rise in rack‑level power densities. Liquid cooling is advancing quickly and can manage far more heat than ever before, but single‑rack densities approaching 2MW and beyond are increasing faster than these solutions can be deployed at scale. The real challenge is delivering this capacity sustainably – balancing cooling performance, energy efficiency, and power availability – all while accelerating build timelines to keep up with customer demand.
For more from Colt DCS, click here.
