Why cooling is the ticket to data centre growth

Grid constraints are a critical challenge for the data centre industry, particularly as the AI era cements itself across industry. However, the main issue isn’t just cooling compute, it’s doing it without overwhelming an already strained grid.

Currently, one of the areas with the most potential is waste heat conversion – using excess data centre heat to give power to nearby buildings like houses. So why isn’t the data centre industry doing it more?

Capacity spoke with Mihir Nandkeolyar, director business development global data centre solutions at Johnson Controls, on how new cooling technologies could usher in the next era of data centre growth.

Confronting a changing power landscape

AI-driven demand is contributing further to grid concerns. In Nandkeolyar’s experience, some of the biggest grid-related challenges revolve around capacity constraints.

“Where a new data centre might have been 20, 30, or 40MW, now add a zero to that or more,” he explained. “The building blocks that even folks like Nvidia are defining as an AI Factory are a gigawatt (GW) – and that’s at least 20 times what a traditional cloud data centre would have been in size.”

With the grid needing all of that power available at any given time, it causes what Nandkeolyar refers to as a “traffic jam”. He explained how connection requests are putting larger pressures on operators, as they are having to deliver more.

“Virginia, for example, used to be a very popular location for data centres. If you walk up to the grid operators today as a data centre operator and request a 100MW or 300MW connection, they might tell you you’ve got to wait three to five years,” he said. “Even in Europe, in some of the bigger markets and major cities, wait times are exceeding two to four years. It’s prompting people to move their capacity elsewhere (ie. The Nordics), or to find energy by other means to run chips.”

Sustainability is a significant consideration for the data centre industry. For on-site-powered data centres, only 35-50% of fuel becomes electricity – the rest is high-temperature thermal energy that can be recovered to drive cooling to reduce cooling demand. Nandkeolyar explained how turning waste heat into cooling power is a promising solution, and can be made possible by the latest developments in absorption chiller technologies. However, it remains somewhat of an untapped market.

“When it comes to waste heat reuse from on-site power, this is where things become really unique, economically advantageous and sustainable for data centre operators,” he said. “Using absorption chillers, which are heat-driven rather than electrically-driven, you can use the heat from the power generation, not the chips, to drive the cooling process.”

These chillers can operate at temperatures without the need for evaporating water to remove heat. The heat energy produces the cooling – a method that is starting to become more popular as grid constraints drive operators towards on-site power.

“So you offset the additional electrical consumption and subsequently the gas or fuel consumption that was used to drive the power,” Nandkeolyar added. “It’s actually a triple benefit: less fuel used, less water used and overall less electricity used.”

Tapping into the cooling revolution

Absorption chiller technology recovers otherwise wasted energy from generators to power cooling, thereby freeing up more power capacity for IT load. As on-site power becomes increasingly prevalent, Nandkeolyar said the heat is now so local to where the cooling need is, the physical proximity makes it worthwhile to consider a thermally-driven chiller rather than an electrically-driven one.

“When the heat was at a power plant 100 kilometres away, you’d lose most of it in transit,” he added. “The physical proximity is what makes it possible to use heat instead of electric power to drive cooling. It’s almost like free cooling – the heat exists anyway, it’s going to be vented out anyway, so you might as well use it.”

While this isn’t a new technology, typically used in industrial sites, it hasn’t really been used at scale before. Nandkeolyar told us how new use cases in the data centre industry will require people to become more comfortable with it, which takes time.

“From our standpoint, we’ve been using this technology for over 100 years and we have deployments across Europe and Asia,” he added. “We have test facilities where you can replicate the actual pressure of steam or hot water you’d see at your site and watch the equipment run. That’s the kind of reassurance that helps customers gain the comfort they need compared to a traditional electrically driven chiller.”

There is an argument in the industry that future facilities will be differentiated by how they manage energy and heat, rather than just compute. For Johnson Controls, this aligns perfectly with their portfolio – with the company having refreshed and reinvented its heat pump and heat recovery chiller several years ago.

“We incorporated the latest refrigerants to achieve higher temperatures and decarbonise more buildings,” Nandkeolyar explained. “Decarbonising buildings through electrified equipment is one of the pillars of our strategy under our new CEO. Pairing that technology with data centres to support community decarbonisation falls perfectly within both our strategy and our capabilities.”

As far as absorption chillers, Johnson Controls is heavily focused on working with power plant design engineers to understand how they can be used as an asset to cool both the power plant and the data centre. To achieve this, the company has also been investing into training service technicians specifically on this type of chiller.

“If you’re going to have dozens or even hundreds of these units at a site, you need trained service technicians you can rely on for not just startup, but for the 20 to 30 years of the facility’s lifespan,” Nandkeolyar added. “Investing in that ongoing service capability is very front of mind for JCI (Johnson Controls International).”

Data centres of the decade: What will set future facilities apart

Future data centre facilities will be differentiated by how intelligently they manage energy, heat and water – rather than just compute – as the public look to the industry to manage sustainability concerns. Notably, chips with higher compute capabilities generate more heat.

For Johnson Controls, managing this involves expanding its heat rejection operations. In January, the company announced its new YDAM and YORK YK-HT chillers, both air-cooled and water-cooled, which have magnetic bearing compressors to support 45°C warm-water cooling.

“We’ve invested heavily in heat rejection equipment that rejects more heat per square metre of space,” Nandkeolyar said. “[The new chillers] reject heat using less land.”

He added: “For the heat transfer segment, the same footprint that might have held a 100–200 kW computer room air handler can now accommodate a one or two megawatt CDU, enabling much greater density.”

Johnson Controls also announced its intention to acquire Alloy Enterprises, a thermal, mechanical and materials sciences technology innovator, to advance its leadership in the data centre cooling segment.

“With their advanced designs, we can achieve greater cooling density, helping chip vendors continue their growth with higher-powered chips within a similar cold plate footprint,” Nandkeolyar added.

The company is hoping to maintain a competitive edge by looking at different ways it can support its customers in the cooling space. A significant consideration for that is scale, with operators needing more power connections and equipment to achieve stronger growth. Nandkeolyar explained how Johnson Controls is investing plenty into its factories and expanding domestic production in the EMEA and APAC regions, where its customers are are to provide local cooling solutions.

“As temperature ranges, density needs and efficiency requirements change, different technologies and compressor types come to light,” he said. “We’re evolving our compressor technology to deliver the best efficiency and the lowest power draw for our customers.”

He added: “As new chip technology or AI functions change how a data centre is operated, at what temperatures, or physically where it’s built, that informs a lot of different things across the thermal chain and drives our medium-term strategy.

“It’s a continuous cycle of responding to where the industry is going.”

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