Telehouse completes fossil fuel-free datacentre retrofit as £251m West 2 build begins

The Docklands datacentre cluster has gained a newly retrofitted, fossil fuel-free facility and is set to expand further.

Operator Telehouse has completed refurbishment of Telehouse South and begun construction of its £251m West 2 building.

The Telehouse South project has removed gas-fired boilers and water heaters from the former Thomson Reuters building next to the Thames and replaced them with heat recovery systems that warm all occupied areas using waste heat from the data halls. 

Meanwhile, cooling has been migrated from end-of-life heat rejection equipment to latest-generation Trane chillers that deliver free cooling – in other words, no mechanical assistance – for around 78% of the year, according to Julian Hennessy, projects director for development and construction at Telehouse.

The result is a power usage effectiveness (PUE) rating of 1.27, down from 1.74 under the previous infrastructure. According to Hennessy, that beats the 1.3 target set by the European Climate Neutrality Pact for existing buildings by 2030 – a goal Telehouse has signed up to deliver.

The chilled water system operates as a closed loop with no adiabatic water consumption. “It’s filled once, it’s maintained once a year, it doesn’t constantly use water,” said Hennessy.

The system works on the same principle as a car radiator – fill it once and it runs with just infrequent top-ups.

Telehouse acquired the building in 2020 from Thomson Reuters, which had used it as a mixed datacentre and office facility with three floors of trading desks. The building was originally designed by architect Richard Rogers with a modular construction that allowed any floor to serve as datacentre or office space. 

The building envelope has been completely replaced, roof insulation thickened, external facade renewed, and all electrical and mechanical infrastructure stripped out and renewed.

According to Hennessy, construction partner Skanska achieved a 97.4% waste recycling rate, diverting materials from landfill. The project also saw office furniture donated to local schools and community organisations. Some 900 workers were on site during the project, alongside 20 apprentices and 14 graduates. The operator funnelled £80,000 in donations to two local charities – First Love Foundation and Leaders in Community – and hosted careers days for young people in the area.

Backup power comes from 12MW of new generator capacity at N+1 redundancy, equipped with catalytic converters and classified by the Environment Agency as “better than best available technologies”. The site is permitted one hour of generator testing per month and a single six-hour “black building” test per year – tight constraints that reflect its location in a residential area.

Hennessy said the campus holds critical national infrastructure status. “About 75% of internet traffic flows through our North building and our campus,” he said. “We support all of the financial institutes you can think of, all the streaming services you can think of, and the rest. It’s probably integral to London that we remain going.”

Telehouse North – the operator’s first building, opened in 1988 – and provides access to more than 1,000 connectivity partners. Hennessy said it is the most connected datacentre on the campus – “probably in Europe and arguably the globe”. The London Internet Exchange (Linx), which started life with a single switch in Telehouse North in 1994, now interconnects more than 900 member networks across the London metro, including those of Apple, the BBC, Google and TalkTalk.

Despite this density, the Docklands campus – five buildings totalling roughly 65MW of IT capacity across the cluster – remains firmly in the edge datacentre category by contemporary standards. “We’re pure edge,” said Hennessy.

Current rack densities at Telehouse South sit at 5kW to 10kW, with the most demanding deployments reaching 45kW to 50kW – for a likely total of about 13.5MW across five floors when fully subscribed. The operator has deployed liquid-cooled rear-door heat exchangers for a small number of racks that draw 55kW, while the new West 2 building will support up to 100kW per rack if required – but Hennessy is clear about where the campus sits in the market.

“Megawatt rack level of stuff is going to be in the huge datacentres, probably somewhere else, and out in the countryside,” he said. “I don’t think you’d actually be able to put a megawatt rack on that aisle. It would go straight through the floor.”