Power and renewables

What the new ASHRAE standard means in a nutshell

Data management and data quality

If you think technology is accelerating in your life, you are not alone.

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) is the governing society responsible for developing building design as well as energy efficiency standards and guidelines for the new construction environment. Until recently ASHRAE had not developed a design standard to specifically address the data center environment. In fact, there had been several white papers that all echoed the need to develop new tools and methods to address the growing popularity of data centers.

So, after two years, ASHRAE released its new “90.4P-2016 – Energy Standard for Data Centers” in late 2016, bringing a much-needed standard for the data center community.

According to ASHRAE, this new standard, among other things, “establishes the minimum energy efficiency requirements of data centers for design and construction, for creation of a plan for operation and maintenance and for utilization of on-site or off-site renewable energy resources.”

That’s a mouthful. In essence it means no more guessing about the best way to plan for a new data center or make an existing data center more energy efficient, which has become critical for today’s utilities and data center operators.

The starting point

It is no secret that the number of data centers is increasing every year. Seven years ago data centers consumed about 2% of all U.S. electricity. This year, the Department of Energy predicts that consumption will reach 4% – with similar growth anticipated in future years. That growth can be attributed to increased workloads, more applications and users, and ever-increasing data storage requirements.

It didn’t take long for data center owners and operators to start focusing on energy efficiency as a way to control costs while meeting increased demand. The problem was that the metrics being used to track data center energy use were inconsistent, if they were tracking use at all. In 2010 industry leaders finally agreed on a governing rule for data center energy efficiency measurements, metrics, and reporting conventions, called the Power Usage Effectiveness (PUE).

Today PUE provides an indication of the efficiency of data center infrastructure systems and has become the most globally recognized performance metric for the energy efficiency of data centers and related infrastructure support systems.

Why the change

Within time users found that the new PUE standards had some shortcomings: First, they realized that PUE is an energy standard and not a design standard, since it allows data center operators to measure the effectiveness of power and cooling systems over time. PUE only measured the relative difference between power consumed on IT equipment and the energy consumed on IT and infrastructure combined, meaning it was not the best tool for determining the overall energy consumption at the facility level.

The existing ASHRAE 90.1 standard had its own limitations when it came to designing and developing data centers. It is mainly prescriptive-based rather than performance-based. As a result, ASHRAE 90.1 focused on what companies must do, instead of what criteria they must meet. It almost universally required an economizer to be a part of overall facility design, but such a requirement is often impractical in a data center design application.

What’s next, what’s new:

This shortcoming led ASHRAE’s technical committee to develop a new standard that would be more practical for the data center industry. One of the committee’s focal points was to develop a standard in which calculations would be based on representative components related to design, rather than on the well-known PUE energy-efficiency metric that requires actual in-use operating data, which can’t be realistically calculated in design.

Based on the committee’s efforts, in September 2016 ASHRAE published its new performance-based standard (90.4P-2016), establishing the minimum energy efficiency requirements for data centers. This new standard spells out the energy-efficiency criteria data center designers must meet and details how to perform calculations that demonstrate compliance. It also contains recommendations for the design, construction, operation, and maintenance of data centers, while focusing on the use of both on-site and off-site renewable energy.

The language of the new standard:

Calculations are done in two parts: the mechanical load component and the electrical loss component. After determining the calculations of both the MLC and ELC, these calculations are compared to the maximum allowable values based on climate zones. Compliance with Standard 90.4 is achieved when the calculated values do not exceed the values contained in the standard. An alternative compliance path is provided to allow tradeoffs between the MLC and ELC.

Under this new standard, these calculations must be equal to or less than the values listed for each climate zone. The assumption is if the worst-performing elements of each system meet at least the minimum efficiency or maximum loss specified, then the overall facility will be reasonably energy efficient.

This is the whole point.

Post Script: DNV and Data Centers

DNV has successfully designed and implemented data center energy efficiency projects on behalf of our utility clients for more than eight years. Our team has significant experience on both new construction and retrofit data center EE projects, from small server closets to co-lo facilities. We work through the entire cycle of project identification, justification, and evaluation, and follow this up with detailed engineering analysis and post-installation review, assuring that the promise of a data center EE project is fully realized.

Our team also is available to work directly with enterprise-wide data center operators to assist them in company-wide energy efficiency initiatives. For more information, contact John J. Greco. John is a D.O.E. Certified Data Center Energy Practitioner, Certified Energy Manager, Certified Measurement and Verification Professional, Certified AEE Building Sustainable Energy Technician Trainer, Certified Lighting Energy Technician, and holds a Bachelor of Science degree in Electrical Engineering Technology from the State College of New York