How to make your data centre greener

Tuesday, 08 February, 2011



Overseeing the green data centre program in Digital Realty Trust facilities around the world has given Jim Smith* the opportunity to speak at numerous data centre conferences, share case studies about energy-efficiency initiatives in facilities, and offer advice about best practices for making data centres greener and more sustainable. Smith has gained valuable insights from attendees in the best practices for greener data centres, which he shares with Voice&Data.

Often one walks away from these events having learned much from the attendees: a powerful reminder about how data centre professionals collaborate on this issue. The free exchange of advice, data and best practices related to energy efficiency unites people in the data centre industry across geographic borders, regardless of whether they are based in Australia or London, New Zealand or Seattle, or Singapore or Miami.

In an industry where we all spend a great deal of time - maybe too much time - stuck inside the four walls of our own facilities with our eyes focused on the ‘nitty gritty’ issues of keeping IT equipment up and running, this is an issue that breaks down those walls and turns our community into a truly global one.

Frequently people ask how environmental regulation X or carbon legislation Y or green corporate directive Z impacts data centre operations and what it means for green initiatives that fall heavily on the shoulders of the data centre team. I could spend a lot of time walking through the different flavours of regulations and legislation that are on the horizon (as well as trends in green IT directives coming from corporate boardrooms), but I won’t. Why? Because those details don’t change the basic fact that regardless of where you are and which company you work for, we will all be asked to make our data centres more energy efficient and to report results in a way that proves compliance.

We’re all in the same boat. We’re all going to be asked to reduce energy consumption and carbon usage by a significant percentage, and the key question is, therefore, what works?

There are a hundred things that might work, but to test all of them would require data centre professionals to reinvent the wheel over and over again. I have seen a number of green initiatives that literally hundreds of companies around the world are trying. Colleagues and peers around the world are kind enough to share the results of initiatives in their facilities. Not everything has a meaningful impact on energy efficiency, but the things that do work really make an impact. Most of these are also relatively simple and cost-effective. The bottom line is that, with some simple, non-expensive steps, companies can see energy-efficiency gains of 10, 30 or even 50% in their facility operations.

Measure it!

If you do nothing else, measure. It is the foundation of every effort to increase efficiency. If you are not measuring energy usage and the percentage of electrical power being delivered to IT equipment, you need to do that before taking any other steps. To increase your data centre’s energy efficiency, you first need to understand how you are using it and establish a way of measuring your efforts to move towards higher efficiency.

Believe it or not, many companies are still not metering power consumption in their data centres. Our company has commissioned annual surveys looking at a number of green data centre trends, and measurement is one of the key things we ask about. Metering has become more prevalent over the past few years, but a remarkably high number of organisations still do not have metering equipment in place to make even the most basic measurement of how they are using power and establishing a baseline for energy-efficiency improvement.

If you are measuring, great! You are ahead of the game and should be commended for making that minor but critical investment. If you aren’t metering, get started. The equipment is inexpensive, easy to have installed and pays huge dividends.

Focus on improving PUE

So measuring is a must, but how to measure has been a point of discussion in the data centre industry over the past few years. That debate is dying down now, though, as the industry has built consensus around PUE (power usage effectiveness) as the key metric for evaluating facility efficiency.

PUE provides a clear methodology for measuring how much power is successfully delivered to IT equipment within the data centre (ie, IT load) versus supporting functions such as operations of power components such as UPS systems and PDUs, cooling equipment such as CRACs and chillers, and other infrastructure such as lighting.

PUE is calculated by taking measurements at key points in a data centre’s power infrastructure and dividing a facility’s total power by the power successfully delivered to IT equipment. In a hypothetical facility that is completely efficient, the facility would use no energy and 100% of available power would be delivered to the servers and other IT equipment. This hypothetical facility would have a highest possible PUE rating of 1.0. Facilities that have a PUE rating between 1.1 and 1.9 are highly efficient, but the typical data centre facility worldwide has a PUE rating only in the high 2’s or even above 3.0. In contrast, the PUE metrics for highly efficient data centres are in the 1.2 to 1.6 range.

Simple steps towards a lower PUE

Many of the most effective steps you can take cost little or nothing and can be achieved immediately by your existing team.

The first is not ‘sexy’, but it is effective. It involves walking the facility and patching gaps in the raised floor and drop ceiling tiles that create leaks that interfere with efficient airflow. By sealing holes in your tiles and filling in gaps between tiles and the edge of IT equipment, you will reduce the burden on your cooling equipment and use less electricity. I have seen customers hand their team members a roll of duct tape and some weather stripping, send them on a half-hour walk through the facility, and see immediate, measurable gains in their PUE rating. A few minutes and $10 in materials can literally save you tens of thousands of dollars and move the needle in a way that will help you meet whatever green/carbon guideline you are facing.

Another best practice involves no cost at all: raising the operating temperature of your data centre. Most data centres are too cold and the setpoint for the thermostat could safely be raised several degrees to reduce the burden on cooling equipment. Engineering organisations and IT vendors have both expressed support for higher operating temperatures that are more energy efficient while remaining safe for building infrastructure and IT equipment. As an example, raising the setpoint from 20 to just 22°C can have a dramatic effect on energy usage, and it is a change that can be made today without investment.

Containment is the theme of the next best practice as well: utilising hot aisle/cold aisle configuration. The Uptime Institute has been preaching the benefits of hot aisle/cold aisle design for years and it works. Many companies start their data centres with this configuration as a design principle, but as data centres evolve organically the positioning of IT equipment often drifts from that ideal.

Another simple step towards higher energy efficiency is to collaborate with your power provider and take advantage of green programs they offer. Many utilities have been incentivised or mandated by government agencies to offer energy-efficiency programs to customers, and an increasing number of power providers have sub-programs specifically aimed at data centre facilities.

Using outside air

The tips above are immediately implementable for existing data centre facilities, but here’s another initiative that should be up for discussion when your organisation looks at a new facility. Using outside air to offset the need for 24/7 reliance on cooling systems was at one time a controversial, experimental technique for increasing energy efficiency, but this strategy is no longer out of the mainstream. Airside economisation has been proven safe and effective in countless real-world deployments.

It is not possible to use outside air in every location or for every data centre facility, but when it is appropriate it can have a dramatic impact on energy efficiency bringing PUE metrics down to the 1.2 to 1.4 range and saving millions of dollars in energy costs.

*Jim Smith is the Chief Technology Officer of Digital Realty Trust. He oversees data centre development and Digital Realty Trust’s efficiency and green strategy, and power procurement & energy management. Over the past four years, Smith and the Digital Realty Trust team have delivered more than 300 MW of UPS capacity on over 60 data centre projects in North America and globally.

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