The power-hungry data centre industry has pledged to go net-zero by 2030. We talk to data centre designers and operators about the latest trends in data centre sustainability

Although data centres have become much more sustainable over the past decade, the rising demand for data has been so exponential that data centres are among some of the world’s biggest consumers of power.

Data centres account for 1-1.5 per cent of global energy consumption – equivalent to the aviation industry – and this is projected to rise to eight per cent by 2030 if nothing is done. Data centres in the EU are responsible for 2.7 per cent of the territory’s demand.

Electricity used for IT and cooling systems accounts for approximately 86 per cent of total energy consumption in a data centre. Cooling alone can account for up to 40 per cent of total energy consumption from a data centre.

While new data centres take sustainability into account from inception when it comes to infrastructure building, legacy data centre continue to consume huge amounts of energy.

The data centre industry, under pressure from regulators, investors and customers, has acted to develop and adopt sustainability to try and limit its impact on climate change.

Reacting to global concern about how vociferous these data centres are when it comes to energy consumption, the industry – led by big players such as Google and Microsoft – has committed to three-quarters of data centre energy consumption being renewable or carbon-free by 2025.

And to being completely climate neutral by 2030.

David Watkins, solutions director at Virtus data centres, says that in addition to the data centre sector as a whole having its own net-zero by 2030 pledge, pressure to hit that target comes from customers.

Watkins says: “Most of the organisations that that we work with have their own very stringent sustainability criteria. We are asked to provide information from our data centres as to performance directly into our customers sustainability reports as well. It’s a real focus area, both for us as an industry and also for our customers.”

However, the push for data centre sustainability can also be big business. The green data centre market is expected to grow at a compound annual growth rate of 7.5 per cent from $36bn in 2021 to $55bn by 2027.

Power usage effectiveness

Data centres measure their energy usage effectiveness by a measurement called Power Usage Effectiveness (PUE). Basically, the energy you’re consuming to actually run your servers is measured as “one”; anything over that – such as the cooling infrastructure, building systems security, general heating, etc. – is added on top.

Only a few years ago, the PUE was up to two, which meant that for every kilowatt of computer storage and networking, you would use another kilowatt of energy to support it.

PUE averages 1.55 today, but newer installations achieve far better performance. The more efficient your building, the less energy you’re consuming.

Data centre operator Kao Data says it has an SLA-backed PUE of 1.2 for its Harlow campus.

And these slight differences matter when it comes to cost. Paul Finch, chief operating officer of Kao Data, points out that lowering your PUE to 1.2 would have saved a facility in the region of £2.51m -£3m a year in running costs – and that was before the Ukraine war. That same figure has probably tripled to £9m a year by now.

Trends in data centre sustainability

Finch is perplexed by the sudden attention paid to data centre sustainability, given that it’s always been embedded in the DNA of Kao Data, which operates three sites in outer London.

Says Finch: “We have always tried to do things in a sustainable manner. It’s as if everybody’s just woken up and smell the coffee. Sustainability has always been in the foundations of Kao Data at its very core.”

Sustainability goes hand in hand with reliability, he says. You are not such a hostage to yoyoing energy prices if you use renewables. Also, sustainability reduces both short-term capital expenditure and long-term operational expenditure.

Finch says: “Really you end up ticking all the boxes, and it makes complete economic sense to do things in a sustainable manner.”

Getting rid of diesel fuel

Data centres need to have backup diesel generators in the event of power network outage. Many data centres handle critical Government infrastructure, such as the NHS. One data centre handles Government communications with the nuclear submarine fleet – and infrastructure doesn’t come more critical than that.

However, data centre operators are experimenting with moving away from diesel in favour of hydrotreated vegetable oil (HVO) – synthesised from waste vegetable oils and animal fats – which reduces net CO2 greenhouse gas emissions by as much as 90 per cent.

Kao Data has already made the switch to using HVO to run its generators.

Hydrogen fuel cells

Data centres are also exploring hydrogen-powered fuel cells as a backup generator alternative, but the technology is not there yet to provide the amount of power smelly, reliable diesel generators offer.

Hydrogen fuel cells can be easily re-fuelled to provide power to data centres, which are expected to have backup power systems for up to 48 hours. More importantly, fuel cells generate zero emissions, with their only by-product being water.

In February this year, Dutch data centre company NorthC became the first European data centre to install hydrogen fuel cells for emergency power.

Up to 37 per cent of data centre managers are considering implementing this technology in the coming year.

Californian data centre operator Equinix is also developing low-carbon fuel cells in partnership with six other companies. These fuel cells can consume green hydrogen and the consortium was awarded a €2.5m grant from the European Commission in December last year to continue its research.

Equinix says that replacing diesel generators with fuel cells will not only reduce carbon emissions but also save on infrastructure costs, shrink their size, and make them easier to maintain.

Here in the UK, Finch believes that the Government needs to invest in the development of hydrogen fuel cell technology and also help find problems to the wider issues of the hydrogen supply chain.

Post-Covid, Government perception of data centres has changed, he says, once officials realised how important they were for the day-to-day running of the country, and how crucial they are to infrastructure.

Renewable energy

UK data centre operator Virtus only uses renewable energy, generated from solar, wind and hydro power, for its data centres – increasing demand for renewable energy and encouraging investment into the sector to meet that demand. For example, Virtus is exploring signing a Power Purchase Agreement (PPA) with its energy supplier, guaranteeing to buy energy from the company for 10-15 years. The energy supplier can take that PPA to the bank and borrow against it.

Virtus points out that by only using renewable energy, it has been insulated from the global energy price shock triggered by the war in Ukraine.

Again, Equinix became the first data centre operator to commit to becoming climate neutral by 2030. Back in 2014 Greenpeace criticised the company for not being committed enough to renewable energy and reducing its carbon footprint. The data centre operator wants its sites to be only powered by renewable energy by then. Ninety-five per cent of Equinix’s energy consumption came from renewable energy sources in 2021.

Airflow management

Airflow management means trying to avoid mixing cold air in supply aisles (used to keep those servers cool and functioning efficiently) and hot air in exhaust aisles (to remove waste heat from the data centre as quickly as possible). Avoiding contact between cold air and hot air minimises the amount of power dedicated to cooling.

Alternating hot-and-cold aisle arrangements of server racks manages airflows and conserves energy. This involves adjusting rack configurations to ensure cold air intakes and hot air exhausts face in opposite directions. By preventing hot and cold air from mixing, data centres can better manage heating, ventilation, and air-conditioning (HVAC) systems.

Virtus tries to ensure that the hot air generated from hot server circuitry does not blow back into cool air flowing over it. Instead, this hot air is captured and fed into the building air conditioning system and recirculated, further cooling the temperature. As such, airflow management becomes a virtuous circle.

Another trend in data centre design is bringing air in through fan walls as opposed to older data centres, which used a raised access floor to provide ventilation routes.

High-density computing

Old-fashioned, energy-hungry air conditioning used to be enough to keep those servers cool. Not anymore as power-hungry AI comes onstream. Chip developers are developing ever-better CPUs to meet AI’s intense computational needs. But this means increasingly high-density heat-intensive racks to meet AI’s demands.

One solution is liquid cooling on high-density computing racks. According to global consultancy Gartner, liquid cooling is up to 3,000 times more effective than using fans to circulate air because it cools the heat source — the server — directly rather than the entire space.

The space needed for liquid cooling is also less, allowing this method to be deployed in smaller, denser facilities.

However, the technology is expensive and to an extent unproven, which makes customers hesitant to adopt it. Hardware manufacturers have been slow to incorporate this kind of liquid cooling in cheaper servers.

AI-assisted automatic cooling control

Using sensors to identify energy waste and deploying software management platforms to maximise efficiency is much more efficient than manually monitoring power. Equinix estimates automated power monitoring could improve energy efficiency in data centres by as much as 30-50 per cent.

In Australia, for example, IT services company Fujitsu saved $230,000 in annual energy costs by installing wireless sensors to collect environmental data and optimise conditions in its data centres.

Another company that has successfully automated monitoring in a data centre is technology giant Alphabet, the parent company of Google. Its cloud-based AI recommendation engine uses real-time data from sensors to predict future consumption patterns and identify how to save energy. As a result, Google has managed to reduce data energy consumption by 40 per cent.

International design firm Scott Brownrigg, whose designs include the planned Belvedere data centre in East London, is talking to an airport and a hospital about using AI to provide an incredibly detailed real-time 3D model – what it calls a digital twin. It’s kind of next-generation computer aided design (CAD), which architects have been using for decades.

Sam Stevens, director and head of advanced technologies at Scott Brownrigg, says: “The idea would be that the digital replica of the building becomes a tool to assist the management and running of the facilities, for example an alarm may flash up on screen to notify your facilities manager when a piece of equipment needs to be tested or changed. It’s almost like a living 3D model that will be running in real time.”

Heat recovery

More powerful, denser computers mean more heat. “You can’t beat the physics,” says David Watkins, solutions director at Virtus. “However you put in electricity, it’s always turning to heat, and then you’ve got to get rid of that heat.”

As we have seen, the latest generation of high-density computers use chilled water instead of air conditioning to keep cool – and the sector is exploring how to connect that now-hot water to feed a local swimming pool or to heat a school, something which is quite common in Scandinavia.

Equinix’s planned PA10 data centre in Paris, France hopes to divert waste heat from customer equipment to be reused in the community heating network.

In addition, this new data centre will include a rooftop greenhouse with a water recovery system that will help retain rainwater and reduce the amount of wastewater sent into sewers.

Stevens points to the Lefdal Mine datacenter in Norway, which recycles heated water for local fish farming and waste from that goes into fertiliser for farming, as an example of the circular economy.

He sees an architect’s role as partly getting stakeholders talking to one another when it comes to sustainability, so that a property developer could include having a data centre on a site to provide waste heat for homes or vertical farming or leisure facilities, such as a swimming pool, all of which need hot water.

Stevens says: “We’d like to see more joined-up thinking between developers and data centre providers, because there’s an opportunity to have mutual benefit.”

Of course, data centres have had a bad press of late, given stories of data centres grinding away to mine bitcoins while heating up the planet.

However, it may be that once people appreciate that having a small local data centre could power the local swimming pool, that attitude could change.

Stevens says: “People may not realise, but every time they’re using their phone for something like WhatsApp or posting on social media, that stuff has to be stored somewhere. We’re interested in how the energy that goes into these storage locations can be reused at least once more, for example, using waste heat and sharing it with neighbours could potentially reduce people’s energy bills. Could this transform our relationship with data centres into something that provides mutual benefits and the conversation switches to, ‘Why can’t we have a data centre near us?’”

Net zero by 2030?

Finch and Watkins are both confident the industry will fulfil its pledge to be net-zero by 2030.

Finch says: “Just look at the improvements the industry has made over the past decade and it’s astonishing. The improvements have been dramatic.”

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