With energy bills accounting for as much as 60% of a data centre’s overall operating costs, Chris Cutler, account manager for Riello UPS, argues that improving efficiency and cutting carbon shouldn’t just be seen as a ‘box ticking’ exercise to satisfy the environmental lobby, it’s a hard-headed business necessity that will boost your bottom line.

It’s clear which way the wind is blowing… The ‘Internet of Things’, increased interconnectivity, shifting consumer behaviour favouring online over more ‘traditional’ ways of doing things, the unstoppable march towards Industry 4.0.

Conservative estimates suggest there’ll be at least 50 billion connected devices by 2020. The implications for all of us working throughout the data centre sector are obvious. Demand for data – and the vast amounts of energy needed to safely store and process terabytes of it – is only going to get bigger.

But with decades-long lack of investment resulting in a National Grid creaking at the seams, it’s not simply a case of increasing electrical capacity to meet these unprecedented needs. A new nuclear plant takes 20-plus years to build and we still haven’t yet come close to fully harvesting the potential of renewables. So we need to be smarter and do more with less – improved efficiency isn’t just desirable but essential.

Of course, the concept of a ‘green data centre’ is nothing new and great technological strides have already been made in recent years to minimise the environmental footprint many facilities have. But there’s still plenty of work that could – and more importantly, should – take place. And not simply to tick a corporate social responsibility box either, there are tangible business benefits to improving data centre energy efficiency.

How much energy does a data centre use?

Data centres are said to consume around 3% of the total global electricity supply and account for 2% of the world’s greenhouse gas emissions – to give you some sort of context, that’s the same as the airline industry, itself hardly a noted cheerleader for environmental best practice!

In 2015, just over 416 terawatt hours of electricity were needed to power data centres throughout the world, 38% more than was consumed in the whole of the UK (300 terawatts). Here in Britain alone, the total power requirement of data centres is estimated to approach nearly 3 terawatt hours per year.

Clearly, that’s a lot of energy. And those demands are only likely to increase. Some industry analysts even claim the amount of energy used in data centres doubles every four years, despite some of the huge technological advances made in hardware.

Is PUE still the ‘Holy Grail’ or a flawed metric hijacked by marketers?

Data centres predominantly use power in two ways. Firstly, to run the IT equipment that they house, such as the servers. And secondly to provide the air conditioning that’s essential to keep those servers cool enough to function reliably without the risk of overheating.

Electricity is a data centre’s single largest operating cost, accounting for anything from 25-60% of its total overheads. And when we’re talking about a large facility that typically consumes 30 GWh of power a year, that quickly adds up to an annual bill upwards of £3 million.

We’re living in the age of hyperscale datacentres. Apple, for example, is building a single $1 billion super-facility in Ireland that will eventually use 8% of national power capacity.

At that level, any efficiency shortcomings and unnecessary waste will obviously be magnified. But whatever their size or set-up, whether on-site, colocation, or cloud, no data centre can afford to ignore ways to be more energy efficient and reduce their data centre power consumption. Indeed, plenty of providers are being forced to adopt energy efficiency best practice to meet strict environmental legislation and mandatory carbon reporting targets.

Recently, PUE has a growing army of critics who point out several flaws in its rather simplistic methodology

In the first few years following its championing by the Green Grid group of IT professionals in 2007, for many data centre managers, this drive for efficiency focused almost single-handedly on improving their Power Usage Effectiveness (PUE) rating.

PUE is a metric that compares a datacentre’s total electrical energy consumption with the amount of energy used by all ICT equipment to carry out useful, data-related tasks. As something that’s relatively simple to measure and repeat over time, it has its merits particularly as an in-house benchmarking tool that encourages continuous, incremental improvements.

In the immediate aftermath of its introduction, it undoubtedly put energy efficiency firmly on the agenda and helped encourage root and branch improvements throughout the sector. Recently, however, the metric has a growing army of critics who point out several flaws in its rather simplistic methodology.

PUE doesn’t take into account differences in climate – data centres in a naturally cold location will obviously need less artificial cooling than warmer environments, but this isn’t reflected in the metric. It also doesn’t factor in IT efficiency, water usage, on-site energy generation, or a site’s carbon impact. So how can you accurately assess two estates when it’s like you are comparing apples with oranges?

The model has also been hijacked as something of a marketing or PR tool. In an increasingly competitive industry, data centres have been keen to report as eye-catching a PUE rating as they can, and that has inevitably left the door open for exaggeration or even manipulation. And even though PUE was published as both a European and global standard in 2016, it isn’t a regulation, so it isn’t compulsory for a data centre to comply, and there still isn’t any robust, independent evaluation process.

EU gdpr

PUE was adopted as a European standard in 2016, but it’s not yet a regulation.

Several potential rivals to PUE have cropped up in recent years, including Effective PUE (ePUE), Green Power Usage Effectiveness (GPUE) – which factors in CO2 emissions and renewable energy use – Data Centre Infrastructure Efficiency (DCIE), and Grid Usage Effectiveness (GUE). However, none of these competing metrics has yet managed to gain considerable traction or support.

So, while PUE is by no means perfect, and its shortcomings need to be kept firmly in mind, until a consensus emerges regarding a better alternative it will likely remain the metric of choice datacentres will turn to.

Improving efficiency with the move to modular UPS

Cooling technologies and techniques have developed considerably in recent years and helped to greatly improve efficiency and cut waste. This is just as well considering air conditioning can account for between a third and a half of a data centre’s total power consumption.

These enhancements on their own aren’t enough though. The good news is that another core element of a data centre’s infrastructure provides similar scope for improvement.

In theory, operating modular systems in ‘Eco mode’ can even push their efficiency to 99%

An uninterruptible power supply (UPS) is an essential part of any data centre design, providing pivotal power protection and acting as a reliable back-up if and when disaster strikes. But just as servers consume power, generate heat, and require constant cooling to operate safely, so too do UPS units.

Whereas in the past this has derailed many data centre drives for efficiency, meaningful technological advances have been made in this area too, namely the rise of modular UPS systems.

Previously, UPS units most commonly found in data centres had been large, standalone towers using older technology that could only achieve optimised efficiency when carrying heavy loads of 80-90%. Such fixed-capacity units often tended to be oversized during initial installation to provide the necessary redundancy, meaning they regularly ran inefficiently at lower loads, wasting huge amounts of energy. These sizeable towers also pumped out plenty of heat so needed lots of cooling.

Fortunately, every UPS has a lifespan, with industry best-practice recommending that a system is replaced every 7-10 years. So many of the units installed during the boom years of data centre growth will shortly be ripe for renewal at just the time when modern, modular versions are available that promise enhanced efficiency, simple scalability, and improved interconnectivity with ‘smart’ grids and systems.

Instead of one large, inefficient standalone tower, a modular system comprises several smaller rack-mount style units, which are paralleled together to provide the necessary power and redundancy. Capacity is closely matched to your data centre’s exact load requirements and can be easily scaled up as and when the time comes for expansion – additional modules can simply be added in on a “pay as you grow” basis.

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A modular UPS is transformerless, which in itself offers up to a 5% boost in efficiency. But where it really comes into its own is the fact it runs at around 96% efficiency across load profiles as low as 25%, something far beyond the capabilities of inefficient static, transformer-based versions. In theory, operating modular systems in ‘Eco mode’ can even push their efficiency to 99%, although this performance boost does need to be balanced against the risk of exposing your critical load to fluctuations in mains supply.

Modular units are significantly smaller, lighter, and generate less heat so don’t require as much air conditioning. They also take up less space, while they are easier to maintain too. Modules are ‘hot swappable’ so if any ever fail they can be replaced without your power protection system having to go offline.

Such systems are also easy to integrate with the Energy Management Systems (EMS) or Data Centre Infrastructure Management (DCIM) software helping to drive forward datacentre automation. These ‘smart’ UPS units are constantly collecting and processing operational data, which can be used to optimise performance and identify areas for future improvement, meaning the pursuit of maximum efficiency becomes an ongoing process.

By providing higher power density in a smaller footprint at enhanced efficiency, the move to modular UPS equips data centres to “do more with less”. And in an era where keeping up with society’s increasing demand for data cannot be met by overloading an already-stretched National Grid, that ability will prove invaluable. The fact it can do this while also reducing energy costs and cutting carbon emissions is a welcome additional bonus.


Check back next week where we’ll show you a practical example where upgrading old, inefficient UPS systems with modern modular models has helped a data centre operator slash its annual energy costs by more than £335,000 and cut carbon emissions by 72%.