Data Center Energy Best Practices: Maximize Efficiency, Increase Savings
Data centers consume – energy, that is. In 2010, data centers accounted for 1.3 percent of total global energy usage, according to Jonathan Koomey, an expert P.h.D. professor on the environmental effects of information technology. In the U.S. during that same year, data centers accounted for 2 percent of the nation’s total electricity. This seems minor in the grand scheme of things, but actually represents an immense amount of energy and money. With recent technological advancements in all industries – from transportation to travel – the demand for exponentially more power and services in cloud computing, collocation facilities and corporate data centers has increased and will continue to do so. According to the IDC (International Data Corporation), the volume of digital content is expected to grow to 2.7 zettabytes (ZB) in 2012, up 48 percent from 2011. Processing all of this data will require more efficient operations, and more intelligent consumption of energy to keep costs down.
This is a challenge that can be faced without expensive and complicated renewable energy sources. Data center managers should instead focus on energy efficiency. By taking the right energy efficient steps and implementing key strategies, companies can lighten the energy load data centers and mission critical facilities deploy in the most cost-effective manner available today. As the Director of Energy Management Services for Schneider Electric, a global specialist in energy management providing integrated solutions and equipment focused on making energy safe, reliable, efficient, productive and green, I am always evaluating the industry and analyzing the best steps to achieve increased energy efficiency and cost savings.
Energy efficiency needs to be prioritized on a company-wide level, requiring commitment from the top of the business chain. With a supported mandate to reduce consumption, facility managers are then free to formalize a plan, create a budget, partner with various providers, execute the selected projects that suit the specific data center’s needs, and finally, measure the energy savings results.
Deciding which solutions to implement is a matter of looking objectively at the specific data center and selecting what is right for that facility. Despite how effective it might be for one, not every energy efficiency measure makes sense for each individual data center.
Availability still wins the day, so every decision should support the ultimate “business” objectives of the mission critical space. There are a number of easy steps to address minor efficiency concerns such as improving rack cable management, filling in air gaps in equipment rows, sealing air leakage sources, and of course, performing equipment maintenance and servicing on a regular basis. But what initiatives make the most impact? In this two-part article, we’ll provide a detailed overview of some valuable steps that can address approximately 80 percent of the energy waste in a data center.
Steps to Maximize Energy Efficiency in the Data Center
Limit the IT load. Virtualization and consolidation are fast becoming some of the most effective strategies to managing power usage and controlling actual IT load. Consolidating various applications onto few servers, usually blade servers, has a major impact on energy efficiency. These steps can also free up power and cooling capacity for energy savings of 10 to 40 percent.
While virtualization lowers energy usage with the diminished use of physical equipment in a facility, it may cause an increase in Power Usage Effectiveness (PUE). For example, a pre-virtualization factor of 100kW of servers with a PUE of two, shifted to a post-virtualization factor of 50kW of servers with a PUE of three.
Warning: facility managers should keep in mind that PUE will likely increase after virtualization. The data center’s total electric bill will be lower; ergo the same fixed loss will be a larger portion of a smaller total.
- Separating Airflow/Containment
Cooling equipment generates heat, and the waste heat of cooling equipment often greatly exceeds the waste heat of power equipment. When cooling equipment is doubled for redundancy, or operated well below rated power, device efficiency will fall dramatically. As such, close coupled cooling in place of room cooling is often a better strategy to “right-size” a facility’s cooling needs.
Any increase in the efficiency of cooling equipment will significantly benefit a system’s overall efficiency. This efficiency is often stifled due to the fact that many data centers routinely mix hot and cold air – effectively limiting the capacity and effectiveness of the cooling system. This can be easily remedied by placing air tiles in the cold aisle, and/or locating supply vents in the cold aisle and return vents in the hot aisle, along with a curtain or hard enclosure to contain the cold or hot aisle.
- Temperature/Humidity Set Points
Current ASHRAE TC9.9 guidelines (as of 2008) recommend a supply air temperature of 64.4°F at the lowest extreme, and 80.6°F on the higher end. Many data centers had been setting temperatures much lower, as low as 55°F. By simply raising the temperature even one degree, data centers can realize energy savings.
When it comes to humidity control in data centers, many managers believed in strictly controlling humidity settings. This allowed CRAC units to “fight” each other with conflicting temperature and humidity schedules. Some CRAC units use a great deal of energy to control humidity, but with ASHRAE’s loosened guidelines for humidity control, facility managers can save energy by simply updating control parameters. Data center managers should be well-versed in the latest ASHRAE guidelines, as a simple adjustment of temperature and humidity set-points can have a greatly reduce consumption.
- Automation and Variable Frequency Drives
Automation and variable frequency drives (VFDs) “virtualize” cooling equipment by matching the cooling supply to the necessary load. VFDs improve control over HVAC functions and provide them with the ability to run at only a percentage of the motor speed, resulting in less power used in the application. This limits any over-cooling in the facility, allowing for some equipment to be turned off completely, for reduced wasted energy.
Automation controls are another measure to continuously reduce energy consumption through the execution of better building controls. Automation systems give managers the ability to integrate, control and monitor various aspects of the facility including HVAC, security, lighting, fire and other systems in one centralized application. Automation controls and VFDs provide a comprehensive method of controlling and adjusting different data center functions, making energy efficiency a priority.
Lance Bishop is director of energy management services for Schneider Electric.
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