The Importance of Power Usage Effectiveness in a Datacenter

When choosing a datacenter, you might look at its guaranteed uptime, its security, or even its customer reviews. But there’s another metric you should also consider: Power usage effectiveness, or PUE. In this article, we’ll explain what PUE is, why datacenter customers should care, and what datacenter operators can do to promote better PUE.

What Is Power Usage Effectiveness in a Datacenter?

Power usage effectiveness measures how efficiently a data center operates. Specifically, PUE measures how much of the facility’s total power usage goes to the IT equipment. We’ll call this the IT Power Needs; it comprises the energy used in: 

  • Storing, processing, routing, and managing data.
  • Running servers, networks, and other computing peripherals/equipment.
  • Onsite equipment (e.g. monitoring and administrative workstations, etc.)
  • Heating, cooling, and environmental control systems.

The formula to calculate PUE is Facility Power Consumption / IT Power Needs. This results in a number ranging from just over 1 to a bit over 3; the lower the number, the better the PUE. That means the datacenter’s energy usage is very efficient.

Why does this metric matter? Because datacenters consume a lot of energy. Not only do the servers, devices, and peripherals require power, they also require specific temperature and humidity conditions – and cooling systems. It all adds up into one very resource-intensive system with a hefty electricity bill. By maintaining a good PUE rating, datacenter operators show how efficiently they’re managing their building and equipment.

What’s a ‘Good’ PUE?

Is there a gold standard for PUE? It is like vehicle emissions, where there is a universally recognized demarcation between good, moderate, and bad?

Not really. While tech leaders like Google and Microsoft can manage numbers quite close to 1, that’s not usually feasible for smaller companies. More importantly, size is not the only factor in PUE; some are entirely outside of the datacenter’s control. A good example of this is the climate. Datacenters need to carefully control the heat and humidity in their buildings; otherwise, the equipment could overheat, malfunction, or even fail. So a data center in a cooler, drier climate could have a lower PUE than one in a hot and humid climate.

To determine the kind of power usage effectiveness you can expect from a local data center, it’s good to find out what other datacenter or co-location companies in the region can manage.  You’ll know what you can reasonably expect. If you can find something lower, great!

Why Should You Care About PUE?

So, why should customers bother with a datacenter’s power usage effectiveness? You’re not paying those utility bills, right?

Actually, you are – albeit indirectly. A datacenter with a high PUE score (and thus less efficiency) is wasting resources. It’s more expensive to run, and those charges get passed on to the customer. That’s one reason.

A second reason is that lowering a PUE (or maintaining a low PUE) is ecologically and environmentally responsible. Energy usage comes with an ecological price tag. Computer equipment manufacturers have worked hard to design more efficient machines and components that drive energy usage down. Customers across industries are demonstrating their interest in supporting environmentally-friendly practices. Finding a data center that takes efficiency seriously is good business sense, both for the bottom line and for the planet itself.

What Can Datacenters Do to Improve PUE?

Improving a data center’s power usage efficiency isn’t as direct as you might think. The number of servers and their configuration – even the type of server cabinet chosen – can heavily impact energy usage. Reducing server’s power consumption by using energy efficient equipment, proper cabling and networking configurations, and using virtualization where practicable can reduce energy demands. But that’s only part of the picture.

Maintaining the correct temperature, humidity level, and airflow can also impact PUE scores. Datacenters have to figure out how to deliver cold air to the servers and remove the hot air they generate; this means not only paying attention to how the airflow is managed, but also to the physical placement and location of the servers. Using a technique known as ‘free air cooling’ (moving hot air outside the building and replacing it with cooler air), datacenters can reduce the cooling system workload, saving themselves a significant amount of energy usage (and money).

As a customer, is there anything you can do to promote power usage effectiveness? Not directly. But you can optimize your usage of the datacenter’s services so you’re not taking more than you actually need. Not only will this help the datacenter maintain its efficiency, it can also benefit your budget; most datacenter charge based on their client’s usage over a defined time period, so you might save yourself some money, too.

TRG’s datacenters take power usage effectiveness seriously; our locations can even offer custom packages that factor PUE ratings into account for each customer. If you’d like to learn more about our datacenter solutions, feel free to contact us today. We’ll work with you to determine the best way to meet your colocation and datacenter needs.

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