How Kao Data used digital twin technology to build UK’s first free-cooled wholesale colo datacentre

Kao Data claims to have built the UK’s first wholesale colocation facility to rely on 100% free-air cooling, as part of a push to provide its clients with access to high-performance computing (HPC) environments that do not rely on mechanical refrigeration techniques to keep them cool.

The Harlow-based operator specialises in providing colocation capacity to hyperscale firms and life sciences-related organisations and is in the midst of a multi-year buildout of its datacentre campus.

This includes the creation of its KDL1 datacentre, where it has opted to deploy a free-air, indirect evaporative cooling (IEC) system – reportedly the first time such technology has been set live in a UK wholesale colocation facility.

The system means that the hot air generated by the facility’s servers is released into the atmosphere, rather than outside air being pumped in to keep the equipment cool.

“The datacentre industry has often stood by tried-and-tested ways of using specific technologies,” Kao Data chief operating officer Paul Finch told Computer Weekly. “Kao Data was designed to challenge and lead the market, accommodating the needs for future-proofing and higher computational performance in parallel with demands for sustainability.”

Since Kao Data’s inception in 2014, the company has made a concerted effort to differentiate its datacentre setups from those offered by the wider UK colocation community by championing the site design principles that are typically favoured by the hyperscale cloud and internet giants when building their own facilities.

To this end, its datacentre campus – understood to be one of the UK’s largest – was the first in the country to be certified as OCP-Ready. This means it has been designed to the standards set out by the Facebook-backed Open Compute Project, which are focused on encouraging operators to embrace open source hardware to improve the efficiency and scalability of their datacentres.

The company also confirmed on 25 May 2021 that its datacentres had acquired certification from Nvidia that states it has capability to support and host workloads that rely on the chipmaker’s latest graphics processing unit (GPU) technologies, including artificial intelligence and high-performance computing workloads.

Being able to accommodate such workloads is another reason why Kao is favouring a free-cooling approach within its datacentres, because mechanical cooling systems would take up space that could be put to better use for its clients’ compute requirements, said Finch.

“The benefits of this approach are many and began during the construction phase, with far greater space utilisation and far fewer mechanical systems required,” he said. “This offered reduced complexity and allowed us to provision for GPU-intensive systems alongside traditional colocation.”

Also, mechanical cooling processes tend to be more energy-intensive, so there are some sustainability and cost benefits that Kao Data will reap through this project, too.

“The free-cooling topology also offers a number of sustainability benefits to customers, reducing both carbon dioxide and harmful fluorinated gas emissions, while allowing us to also implement the monitoring of gaseous contaminates within the technical space,” said Finch.

“This provide the assurance that customer server and storage warranties are never put at risk, while ensuring greater levels of reliability.”

Kao Data worked with its longstanding design and build partner JCA Engineering on the project, which, in turn, enlisted the help of datacentre design and simulation software maker Future Facilities to ensure the operator’s theoretical plan to build a free-cooled facility would work in practice.

Future Facilities did this by creating a digital twin of the proposed datacentre site using its software, so that it could pinpoint any potential and theoretical performance issues that may emerge once the IEC was deployed in the real world.

As part of this work, Future Facilities also drew on the computational fluid dynamics (CFD) simulation capabilities of its 6SigmaDCX software suite, which provided Kao Data with insights and predictions as to how its IEC system would perform in differing internal and external environmental conditions.

“6SigmaDCX is a CFD package which is combined with the modelling of systems found in datacentres and systems that work with datacentres, so we are also emulating control systems for cooling systems infrastructure,” said Alex Dorn, engineering manager at Future Facilities.

“We are including physical characteristics, as well as cooling systems and servers, and we try to include the thermal performance profiles of equipment [in these models], as well. This means the environment is dynamic that we are simulating – so it’s not just a static 3D space with airflow being simulated moving around.

“We’ve got all of these different systems dynamically reacting to their environment, and then that’s connected through the CFD simulation.”

As regards this project, Future Facilities was initially enlisted by JCA Engineering to carry out a design analysis of the external datacentre using the 6SigmaDCX package, which Dorn admits is quite a “novel” task to be asked to perform.

“Modelling within the industry typically has an internal focus, so it was interesting to be asked to look at the external design of the facility,” he said.

“They [JCA Engineering] came to us and said we’ve got this design, and we’d like to make sure it works. So we had to define a shortlist of weather scenarios that we felt were representative and also covered any risk that might be experienced, and then we created what we call a baseline.

“Essentially, that is the first version of the model [digital twin] where we feel that what is planned is suitable for purpose, and you use that as your reference point going forward.”

From here, the company’s work on the Kao Data build progressed so that its software was then used to model the inside of the facility, which can be a complicated process, said Dorn.

“The software itself is very accurate and exacting because it is continually being improved through research and development, but the model produced depends on the inputs and the accuracy and the appropriateness of the inputs as wel,” he said. “The key here is selecting the right inputs, and finding the data necessary to represent the systems involved in the design and operation.”

At the time of the project, external modelling of datacentres using digital twin technology was relatively unheard of, and is a capability Future Facilities only began building into its software suite in 2017.

“It’s pushing the envelope, but it was very important to perform this viability study overall [for the Kao Data build] because how else can you be sure that your design is going to work and that datacentre is going to operate OK?” said Dorn.

And while this project is a UK first, Dorn is confident that with Kao Data demonstrating the viability of free-air cooling in this country, other operators may opt for a similar systems in their new-build facilities.

“It is a bold move and it makes it clear that it is achievable,” he added. “It is a very risk-averse industry and this shows that there is now the science to help manage novel designs and manage the risk of novel designs and novel approaches.”