The Real Role of Sustainability in Modern Data Centers

On the surface, the phrase “sustainable data center” appears to be an oxymoron. Data centers are known to be massive energy consumers. In fact, they are estimated to account for 12.7% of all energy consumption in the United States by 2028 (source: energy.gov). However, that doesn’t mean sustainable operations are out of reach. Through strategies like retro-commissioning and monitoring based commissioning, data centers can significantly reduce emissions and energy consumption leading to more sustainable operations and decreased carbon emissions.

Sustainability in the Built Environment

When addressing sustainability in the built environment, key focus areas for improvement include resource efficiency, carbon emission reduction, and energy consumption reduction. Sustainability should be considered from Day 0 of design and carried through the building’s full life cycle. BranchPattern aims to enhance existing data centers by reducing energy use and emissions and by maintaining those reductions.

 A Primer on Emissions

Emissions are typically categorized into three scopes. Scope 1 and 3 are a small part of the emissions of a data center.  

• Scope 1 includes direct emissions from on-site sources like natural gas for heating, diesel fuel for generators, and gasoline for company vehicles.  
• Scope 3 encompasses emissions from the supply chain, customer activity, product usage, and waste disposal.  
• Scope 2, our primary focus here, involves indirect emissions from the production of the electricity used by the data center.

The composition of the power grid that supplies your data center plays a major role in Scope 2 emissions. For example, the grid powering a data center in northern Virginia consists of about 50% coal and natural gas, 40% nuclear, and 10 % renewables (source: epa.gov). In contrast, a data center in Austin, TX is powered by a grid that is about 62% coal and natural gas (source: epa.gov). These figures may also vary depending on the power purchasing agreement (PPA) your data center has with the utility provider, especially if there are any renewables in the PPA or onsite. In short, the location of the data center and the PPA will greatly drive operational emissions.

Let’s Benchmark First

Before we can start making improvements, you need to understand your current performance. The most used and widely understood measure of data center performance is Power Usage Effectiveness (PUE), calculated as:

PUE = Total Facility Energy / IT Equipment Energy

Like golf, a lower score is better and the lowest you can have is 1.0. Most new data centers have a PUE of less than 1.5, and most target around 1.1.  

PUE is the original efficiency standard, but there are some criticisms of it. For example, improving IT operations can make PUE worse not better. If IT energy decreases, but overall facility energy usage does not decrease then PUE will increase. Similarly, PUE does not consider different cooling strategies and can therefore not be a good comparison tool between data centers.  

Newer efficiency standards are gaining widespread adoption, including emphasis in the latest ASHRAE 90.4 Energy Standard for Data Centers. These include:

• Mechanical Load Component (MLC)
• Electrical Loss Component (ELC)
• Total Usage Effectiveness (TUE)  

Additionally, more sustainability focused metrics are coming into use, including:  

• Carbon Usage Effectiveness (CUE)
• Water Usage Effectiveness (WUE)
• Renewable Energy Factor (REF)
• Energy Reuse Effectiveness (ERE)

‍Set a Goal for Reduction

If PUE is the only metric readily available to you, then measure it to get a baseline use and set a goal for reducing it.  

• If your PUE is over 4.0, aim to cut it in half.  
• If it's near 2.0, aim to bring it to 1.5.  

If you want to focus on sustainability metrics, CUE, WUE, and other metrics are more difficult to measure but not impossible. A qualified commissioning provider can measure these usages and set a roadmap for improvement.

Retro-Commissioning for Sustainability

The first step toward sustainable operation in an existing data center is retro-commissioning. Retro-commissioning is the process of commissioning a facility that either has never been commissioned or hasn’t been commissioned for an extended period.

Retro-commissioning will let you know where you stand in your operations and let you know areas that can be improved. If your data center has not been commissioned in over 2 years, it’s time. Retro-commissioning helps identify:

• Easy to achieve energy savings, such as turning off air handlers that serve empty spaces, moving floor tiles to improve airflow efficiency, or adding hot and cold aisle containment.
• Long term capital improvements such as liquid cooling, air or water free cooling, and PDU or UPS upgrades.

Retro-commissioning is a proven remedy for reducing energy consumption with the added benefit of improving reliability and resiliency in operation.

Now Where Can We Cut Back?

The biggest consumers of energy in a data center are servers and cooling systems. While this article focuses on operational improvements, like cooling, collaboration with the IT team is essential to reduce energy. Regular meetings between facility managers and IT staff can uncover opportunities like:

• Removing zombie servers
• Consolidating or virtualizing racks
• Reclaiming underused infrastructure

Servers are added all the time, but they can also be removed. It is not a one-way street.

On the cooling side, start by evaluating your temperature setpoints and airflow management. Implementing hot and cold aisle containment is a moderate-cost upgrade that can allow you to safely increase cold aisle temperatures, reducing cooling loads and overall energy use.

The Role of Monitoring Based Commissioning

Once retro-commissioning is complete, a proactive strategy must be put in place to prevent energy consumption from creeping back up. Monitoring-Based Commissioning (MBCx), also called continuous commissioning, is a software-based approach that monitors and benchmarks equipment performance. It will give you the performance metrics that you must know for the performance of your data center.  

If you have a Data Center Infrastructure Management (DCIM) system in place, it is an excellent complement to MBCx. It will give you the added benefit of equipment performance and preventative maintenance items that are typically excluded from a DCIM platform. MBCx will help you stay on course and maintain performance gains you’ve worked tirelessly to achieve.

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Sustainable Operation Is Possible

Through the use of retro-commissioning and monitoring based commissioning, sustainable data center operation is possible. A data center doesn't have to be an unchecked resource hog. With intentional action, energy, water, and carbon emissions can be reduced.