Keeping it cool: designing the data center for the AI era

Chris Larsen, CTO, atNorth

As part of our ‘Building for Good: Reimagining the Data Center’ series, this blog explores one of the most urgent and foundational aspects of digital infrastructure transformation: cooling. As AI becomes more central to modern enterprise strategy, one thing is clear: traditional data centers are no longer fit for purpose. High-performance computing (HPC) workloads, especially those driven by machine learning and large language modelling, demand dramatically different infrastructure. Navigating this shift isn’t just about scaling compute, it’s about rethinking the data center with both performance and sustainability in mind.

Too hot to handle?
It’s time to go back to basics and answer a fundamental question: what is a data center? At its heart, a data center is a facility that houses computing equipment – servers and systems that power everything from cloud services to cutting-edge AI. As these systems operate, they generate significant amounts of heat, especially in AI environments where power densities can reach 80–200kW per rack, which are far beyond the capabilities of traditional air-cooled systems.

Historically, air-to-water or fully air-based cooling solutions were sufficient. Today, the rise of high-performance computing is pushing thermal loads to new heights. Efficiently and sustainably removing or reusing this heat has become one of the most important challenges – and opportunities – in modern data center design.

Cooling: the first pillar of AI-readiness
The first, and arguably most talked about challenge plaguing the industry is cooling. Classic data centers relied typically on air cooling systems like CRAC units and hot/cold aisle containment. But these alone can’t keep up with rack capacities beyond 40kW, 80kW, or even 200kW. While this was manageable in the past, the exponential rise in compute density – driven by AI and HPC workloads – has pushed thermal loads far beyond what traditional systems were designed to handle. Now, AI-optimized facilities are turning to more advanced solutions like liquid cooling, either through direct-to-chip cold plates or full immersion cooling.

At atNorth, we’re operating a closed water loop cooling system that easily facilitates the implementation of Direct Liquid Cooling (DLC), which offers a powerful solution by circulating liquid coolant directly over the hottest components to absorb and remove heat more effectively. We work closely with leading cooling technology providers like CoolIT Systems whose DLC solutions are purpose-built to manage the intense heat output of modern processors. CoolIT’s solutions offer precision cooling for AI and HPC workloads, ensure optimal thermal performance, and unlock greater sustainability benefits.

This use of liquid cooling is indicative of where the industry is headed – from closed water loop systems to ground water and even river cooling. These innovations don’t just improve efficiency but also protect infrastructure investments by reducing thermal stress and operational risks. 

Cooling innovation: beyond air, into liquid and ecosystems
Flexibility, scalability and modularity are the first pillars of modern data center architecture. One where next-gen design drawing on innovative liquid-based cooling is crucial. These approaches are not only more effective for ultra-dense workloads but also unlock new possibilities for heat reuse, which is fast becoming a critical enabler of closed-loop, sustainable data center infrastructure.

At atNorth, we’ve long championed this approach. Facilities like SWE01 in Sweden are already capturing excess heat to recycle it through local district heating systems. And as cooling innovation becomes more advanced, so too does the efficiency and viability of heat reuse. Direct liquid cooling, for example, allows for more targeted heat capture at higher temperatures, making it far easier to transfer excess heat into municipal heating networks.

Our new DEN02 site in Denmark will utilize this approach, embedding it into the very DNA of the site design. And as thermal loads continue to rise, this model will only become more relevant. We’re not just facilitating a cooling infrastructure; we’re supporting circular energy ecosystems and turning data center output into a valuable community resource wherever possible.

Let’s build smarter, cooler infrastructure
Across the industry, it’s becoming clear that static, one-size-fits-all infrastructure can’t keep up with the pace of technological change. As AI and HPC workloads continue to accelerate, data centers must be built with flexibility and adaptability at their core. What supports 40kW per rack today will need to accommodate 200kW tomorrow. Redesigning from scratch every few years simply isn’t commercially or economically viable.

This is why scalable, modular design principles are core to atNorth’s Data Center Blueprint. We understand how important it is to anticipate future needs and support seamless scale, without bringing costly disruption. By integrating power, cooling and heat reuse systems from the outset, we’re creating data center environments that are ready to adapt as demand shifts, technology evolves, and sustainability expectations increase.

Building today for what’s next tomorrow
The next generation of digital infrastructure won’t be measured by how much data it processes, but by how sustainably it operates. At atNorth, we’re not just preparing for that future, we’re building it today.

Get in touch if you want to learn more about our Data Center Blueprint and how DEN02 is changing the game.