Data centers and IT equipment are just starting to become increasingly energy-efficient, and there are a variety of metrics, standards and certifications that have emerged. Standards and metrics are important to enable the accurate measurement and comparison of data centers and IT equipment and, along with certification programs, can maintain the integrity of tech companies’ claims for energy efficiency (as I detailed in this post on how a snapshot of a green data center can be misleading).
Here are seven metrics, standards, and certifications companies are using as a lens to show the energy efficiency of data centers and IT equipment:
1. PUE. The leading metric used to show how efficiently data centers are using energy, the Power Usage Effectiveness (PUE) figure, is a ratio of how much energy consumption is going to run a data center’s IT and servers vs how much energy is going to run the overall data center. It was created by The Green Grid. If a lot of the data center’s energy is used for cooling and power conversion, the energy use isn’t very efficient, and the data center will have a PUE closer to two. If very little of a data center’s energy is used for cooling and power conversion (and is instead mostly being used to power its servers), a data center is using energy much more efficiently and will have a PUE closer to one.
2. CUE and WUE. Also created by The Green Grid and meant to be complementary to PUE, the Carbon Usage Effectiveness (CUE) metric looks at the carbon emissions associated with operating a data center (not its construction) and the Water Usage Effectiveness (WUE) calculates how efficiently a data center is using water.
More specifically, the CUE is a ratio of the total carbon emissions due to the energy consumption of the data center (the same one used for the PUE of it) compared to the energy consumption of the data center’s servers and IT equipment (the same one used for PUE). The metric is expressed in kilograms of carbon dioxide (kgCO2eq) per kilowatt-hour (kWh), and if a data center is 100-percent powered by clean energy, it will have a CUE of zero. The CUE could one day be a particularly important metric if there is a global price on carbon.
The WUE is a ratio of the annual water usage to how much energy is being consumed by the IT equipment and servers, and is expressed in liters/kilowatt-hour (L/kWh). Like CUE, the ideal value of WUE is zero, for no water was used to operate the data center.
3. Carbon Intensity Per Unit of Data. Content delivery network leader Akamai has been reporting the carbon emissions related to its cloud computing-based services in the metric of “CO2 per megabytes of data delivered.” Establishing this metric enables Akamai to compare cloud computing energy usage across the industry, and Akamai is also in the process of making this metric available on a monthly basis to its customers. Greenpeace has lauded Akamai for its transparency and reporting of this metric, and gave Akamai the highest grade for “transparency,” out of 10 giant Internet players like Google, Apple and Facebook.
Telecom company Verizon also recently started reporting its “carbon intensity,” which combines Verizon’s total carbon emissions in metric tons (from electricity use of its network and buildings, as well as fuel use) divided by the number of terabytes of data that Verizon transports across its network. That way Verizon can grow its business, but also show that it’s shrinking its carbon emissions per data.
4. PAR4. PAR4 is a metric developed by startup Power Assure that measures server power consumption in different ways, including monitoring idle power, peak power, total utilization power, and “transactions-per-watt.” Essentially, PAR4 enables servers of different makes, models and generations to be compared to one another in terms of energy efficiency. That type of detailed measurement is mostly lacking for servers today. Power Assure says PAR4 is already gaining acceptance from big players like Intel, Dell and Cisco, which have been working to incorporate PAR4 into their systems.
5. LEED. Some data center builders and operators are looking to the building standard LEED to prove their data centers are green. The strength of LEED is that it takes a holistic approach to evaluating the green credentials of a building, and considers materials, location, water use and indoor environmental quality, along with energy efficiency. Buildings that achieve enough points under these five categories are certified by the U.S. Green Building Council.
6. Energy Star. The Environmental Protection Agency’s Energy Star certification, which is widely used for gadgets and computers, can also be used for stand-alone data centers and buildings that house large numbers of data centers. If a data center ranks in the top 25 percent of their peers in the EPA’s rating system, which has been in the works for years and is based on PUE, then it can get an Energy Star label.
7. ASHRAE. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) updated the “90.1 building efficiency standard” for data centers last year, and raised the hire of a group of tech firms including Microsoft, Amazon, and Nokia. The companies said that the standard was “too prescriptive,” detailing specific technology that has to be used, and potentially cramping innovation.
Image courtesy of The Planet.