Part 3—"What’s Your PUE Strategy?"

This third and final article describes how you can start adopting PUE in your datacenter, and how Microsoft has benefited from its long-term use of the PUE metric.

If you do not have anything to adjust that can change your PUE value, you will not be able to take action. However, it is surprising just what you can do to improve your PUE, as you will see when we look at some results Microsoft has achieved.

Implementing PUE Strategies

Examples of best practices you can use to improve PUE are listed in Microsoft’s Best Practices for Energy Efficiency in Microsoft Datacenter (see

The following "top ten" best practices will help you to develop your own strategy to improve your PUE by looking at the big picture:

  1. Engineer the datacenter for cost and energy efficiency.

  2. Optimize the design to assess multiple factors.

  3. Optimize provisioning for maximum efficiency and productivity.

  4. Monitor and control datacenter performance in real time.

  5. Make datacenter operational excellence part of organizational culture.

  6. Measure power usage effectiveness (PUE).

  7. Use temperature control and airflow distribution.

  8. Eliminate the mixing of hot and cold air.

  9. Use effective air-side or water-side economizers.

  10. Share and learn from industry partners.

Three Stages of PUE Implementation

Stage 1 – Sneaker Net

Measuring PUE can start with a "sneaker net" approach (MBWA, or measuring by walking around with a clipboard) to collect the meter readings for the entire datacenter facilities, and the associated amount that can be accounted for by the IT load. It could be as simple as reading the output of your critical load UPS units. Finding your own PUE is the first step. It sounds so simple, but it is amazing how few employees know their PUE. When you do find your PUE, share the number. Identify the range of your PUE by collecting data regularly, and displaying the results for others to see.

Stage 2 – Instrumented Data Acquisition, Some Sneaker Net

The next step is to implement automated meter reading, but don’t expect to have a solution for all devices before you begin this stage. Most power and cooling equipment has the capability to report meter readings, but getting data from all the equipment can be difficult at first until you discover the protocols for each device and network all of the devices. You can build your own meter reading solution, use one supplied by the equipment vendor, or purchase specialist third-party software. Many IT management tool companies have started to integrate power management capabilities into their tools. Alternatively, there are standalone products like Microsoft Dynamics or the OSIsoft Pi System.

Stage 3 – Real Time Data, 100% Automated Meter Reading

The ideal stage is when you have real-time energy consumption data available for the whole datacenter, including environmental conditions. Then, once you are collecting all the numbers, you can build a dashboard such as that shown in Figure 1.


Figure 1 - Screenshot of Microsoft Data Center Dashboard

In the same way as a Network Operations Center (NOC) watches the datacenter operations, additional screens integrate monitoring and provide automated alerts for power and cooling system efficiency. This type of dashboard is useful in the previous stages, of course, but is most effective at this stage.

With constantly changing equipment deployments, load, and environmental conditions, PUE is a dynamic number that will move within a range. Advanced users have the right tools and information to measure continuously how far they are away from the optimal PUE, and automatically detect out-of-range conditions.

PUE in Action

Most of the news around Microsoft’s datacenters is about its state of the art facilities currently under construction (see Less well known is the effort Microsoft puts into improving datacenter energy efficiency in legacy facilities. Figure 2 shows the PUE value for a Microsoft facility from August 2004 to August 2007. After 2 years of energy improvements, the PUE for the site improved by 25%.


Figure 2 Actual data from a Microsoft Datacenter from Aug 2004 to Aug 2007

Examples of non-intuitive changes made to the site, which proved effective in reducing PUE, were cleaning the roof and painting it white, and repositioning concrete walls around the externally-mounted air conditioning units to improve air flow. Both of these changes were validated as effective by measuring the effect on PUE.

Experience at Microsoft has shown that using PUE as a common metric when designing new datacenters and evaluating new technologies can save energy. Figure 3 shows Microsoft’s goals in new datacenter construction, aiming to apply the equivalent to Moore’s Law by doubling the datacenter power and cooling infrastructure efficiency every two years.


Figure 3 Annual Avg PUE Targets for New Datacenter Construction

Voluntary PUE Disclosure

Electricity costs are rising faster than any other costs in the datacenter. Electricity used by datacenters is one of the fastest growing segments of energy use. Combine the rising cost per watt with rising overall consumption and you can see why government officials are concerned about the energy consumption of datacenters. To collect more information about datacenter efficiency, the Environmental Protection Agency (EPA) has asked for a voluntary disclosure of PUE (see

Call to Action

By now, you should be convinced that measuring and monitoring your PUE, and other factors associated with datacenter efficiency, is vital in today's economic climate. Here are some action points that you can use to drive your transformation into an environmentally friendly and reduced cost datacenter operation:

Don’t wait for the perfect time or the perfect tool
What is your PUE? What was your PUE? What should your PUE be? PUE is a simple number that all your datacenter and IT teams should know.

Start collecting data for PUE
Get a clipboard, read the meters, calculate your PUE.

What happens after you've done PUE? You measure other stuff.
What do you do after PUE? Start collecting data on power subsystems, cooling subsystems, IT equipment performance, and carbon emissions.

Provide organizational incentives
Ultimately, PUE provides the ability to measure efficiency of your datacenter. If you want to improve the efficiency of your datacenter, you need to think about how you integrate PUE into your organization’s metrics. Microsoft has made uptime and PUE its top metrics for datacenter managers to report on.

Base chargebacks on power efficiency
Instead of basing chargeback costs of a datacenter on total power consumed, base it on a portion of power consumed that relates to PUE so that you incentivize managers to improve efficiency.

Consider datacenter manager bonuses
Finally, do not forget to reward energy savings and PUE improvements. Bonuses and recognition awards for energy savings make sense when you want to make energy efficiency part of everyday tasks.

This is the last of a short series of articles that describe how Microsoft uses Power Usage Effectiveness (PUE), an industry standard metric for the efficiency of a datacenter. Being able to measure and monitor the effective power consumption of a datacenter in terms of the computing power it contains provides a way to ensure that you make best use of resources while minimizing your environmental footprint.


  • Mike Manos, General Manager Data Center Services

  • Christian Belady, P.E., Principal Power and Cooling Architect

Comments (2)

  1. As some of you know, the Environmental Sustainability team has recently created a Twitter account to

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