John Booth MBCS, Vice Chair of the Green IT specialist group, asks: what is a data centre and why are they so important to today’s digital society?

Data centres are homes for specialised computing equipment, servers, storage and networks; they provide the means of electronic communication for all types of industry, government, commercial entities and academia - processing, storing and transmitting data across the world.

Every banking transaction, online purchase, sat nav request, health care record, entertainment download, transport option, power network, telephone call and shopping purchase - all are routed through data centres. Quite simply, the modern world would not be able to function without data centres.

Origin of the species

Back when BCS was founded in the late 50s, all computing took place in specialised machine rooms. It wasn’t until the early 70s that the use of computers came out of these rooms and on to the desktop.

This was not the demise of the computer room, but an evolution. Those machine rooms still exist, and they’ve grown up. Back in the 50s, they were primarily specially adapted rooms, contained within normal buildings. Today, they can be entire buildings specifically designed to house servers, storage and network equipment; supported by Uninterruptable Power Systems (UPS), power distribution systems, cooling equipment, security and monitoring equipment and leak and fire detection / suppression equipment.

Power generations and consumption

As you can imagine, the energy required to power all this equipment was vast. Due to traditional approaches to cooling, the amount of energy used was sometimes double what was being used by the ICT equipment. In short, data centres weren’t being operated at their highest potential efficiency.

In 2007, BCS joined the Department for Farming and Rural Affairs (DEFRA) and the EU Joint Research Centre to create an EU Code of Conduct for Data Centres (Energy Efficiency). At the time, energy use in data centres across the EU totalled some 54TWh, and it was forecast to rise to 104TWh by 2020. However, as energy efficiency has crept up the political agenda, so actual energy use has reduced...

Or has it? Local energy use has reduced in the UK, but the rise in new data centre facilities globally has meant that the data is now being handled in someone else’s data centre. Globally, it looks like data centre energy use has increased.

A report in 2018 by the Open Compute Project suggests that data centres in Europe will consume 259TWh of energy, although the source is not revealed; the real problem is that the number is a moving target.

Most data centres can be classified as either ‘enterprise’ (meaning, owned and operated by one organisation) or ‘colocation’ (providing professional management and care for several organisations in a purpose-built facility).


The main metric for data centre energy use is Power Utilisation Effectiveness also known as PUE. This was developed by the Green Grid in 2006 and published in 2016 by the ISO as ISO30134-2:2016. It is the ratio of compute verses supporting infrastructure. This can be expressed as PUE = total facility energy, divided by IT equipment energy.

The average PUE cross Europe (from data collected by the EU-JRC under the EU Code of Conduct for Data Centres’ Energy Efficiency programme) is 1.79. That said, some facilities are substantially lower, in the 1.2-1.3 range, meaning that the cooling and other supporting infrastructure is extremely optimised and makes use of advanced techniques in air flow management and cooling ranges.

Other metrics are being developed and are being standardised as part of the ISO30134 series, but also within the EN50600 series.


Most organisations have at least one data centre, it may be simply a cupboard under the stairs or a vast purpose-built data centre campus - but as technology advances, there is no excuse for building an inefficient data centre.

Data centre designs can vary depending on geographic location and the proximity to renewable energy sources or district heating systems (both EUCOC recommendations). They can also vary depending on temperature ranges and the use of free cooling, which has become increasingly commonplace where temperatures allow this mode of operation. Designs for other regions may require compressor-based cooling options.

The standards mentioned above (EN50600) provide ample opportunity to construct a state-of-the-art low energy, low carbon facility and it’s increasingly obvious that energy and carbon related taxes will be applied sooner rather than later.

In fact, the new Streamlined Energy and Carbon reporting regulations require that all energy consumption by an organisation needs to be recorded. The figures will include all the energy used in the cloud (whether located locally or overseas) and, if a telco or ISP (the ‘intensity metric’) also need to be reported, this is (for the moment) GBs of Data Transmitted per kWh.

As the regulations have only been in force since the 1st of April 2019, it is far too early to assess what impact this will have on the industry, or indeed the calculation of energy used in the cloud; although a good correlation will be the actual physical bill from the cloud provider.

There is plenty of guidance available from the BEIS website on this subject.


Data Centres are the hidden skeleton of ICT. Without them, our world would collapse, just as you would if your bones were removed. As such, they are a very necessary component in today’s world.

There is plenty of negative press around the data centre sector and plenty of myths, such as ‘data centres are bad for the environment’ and ‘data centre power use is increasing exponentially’. Both are nonsense.

Data centres, especially the big household names such as Google and Amazon, procure a great deal of renewable energy and in fact, mitigate and offset energy use elsewhere: for instance, reducing business travel via the use of conferencing systems, or controlling software used for logistics and transport. The fact remains, that data centres support the digital economy.

We, in this field are always trying to do more with less. We already use renewable energy, we already design data centres to be as energy efficient as possible and we understand that ICT has two focus points: the first is the greening of ICT itself, the reduction of energy used to manufacture, transport and use. The second is the use of ICT to reduce energy consumption and resource depletion in every other sphere of human involvement. We recognise the use of ICT to support our climate emergency adaption and mitigation efforts.


What does the future for data centres look like? Well, many commentators predict a bright, almost blinding future, expecting to see a data centre on every street corner. And they’d be right. The data centre supports all digital transactions - these can be local: the requirements of 5G, the IoT, AI and autonomous cars. These technologies all require processing power, storage and networks to become local; hence the concept of the edge where small street cabinets could contain active processing, some local storage and networking devices.

In the future, this could be contained within existing mobile phone towers and cell sites. However, the amount of these on UK streets (or more likely on roofs) will be doubled from approximately 26,000 currently to 50,000 or even 60,000 in urban areas.

There are approximately 450 hyperscale facilities (cloud services) worldwide and several more under construction, these will form the hubs in the wheel, surrounded by “edge”. The future is indeed bright!


The BCS Data Centre Specialist Group was responsible for the development of the EU Code of Conduct for Data Centres (Energy Efficiency) and has, in the past, contributed to discussions on a Data Centre Climate Change Agreement, signed between industry and government in 2015.

It could be argued (and it has been) that the DCSG has fulfilled its purpose, but technology changes, as do governments and their views; it is incumbent on BCS to be visible in all areas of ICT across the UK and beyond, especially given the fact that ICT lives in the data centre.