Data Center Energy Use: Energy-Efficient Design Can Yield Significant Energy Savings

New designs for data center process (servers and associated IT equipment) and support equipment (HVAV and power conditioning) hold great potential to improve the energy efficiency of these applications. Recent advances in server technology energy performance coupled with cloud services and on-demand computing have shown potential to reduce server energy use by as much as 89% compared to conventional server systems.

Power Hungry Data Centers

As demand for data processing and storage services continues to expand, new data centers are being built to accommodate this growth. However, data centers are highly energy intensive and are coming under increasing scrutiny to improve energy efficiency in both server design and data center configuration. 

According to a 2007 U.S. Environmental Protection Agency (EPA) report to Congress, U.S. data centers consumed approximately 61 billion kilowatt hours in 2006, representing approximately 1.5% of U.S. electricity use. Data center energy use is projected to grow by nearly 10% annually as the market for data processing and digital storage continues to grow. As a result, incorporating energy efficiency at the design stage of new data center construction is critical to mitigating energy consumption by this rapidly growing sector.

Why Do Data Centers Use So Much Energy?

Data centers require high reliability and strong power density to power their most critical applications: servers/IT applications and the HVAC equipment needed to remove heat and maintain the optimal indoor environment for the highly sophisticated electronic equipment.  In fact, due to the size, power and density of modern data centers, cooling energy loads may equal, or even exceed, the electricity required to power a data center’s IT needs. This combination of process and support loads may make data centers 100 to 200 times more energy intensive (per square foot) than a conventional office building.

Data Center Design Opportunities

Companies are now turning their attention to energy performance to underpin competitiveness. The IT sector’s high performers are addressing this using a combination of approaches:

• IT system design – as the digital processing race unfolds among major IT manufacturers, parallel efforts to reduce the size and energy consumption of processers, servers, power supplies and other network equipment to minimize the footprint of data centers are also underway. As a recent example, HP’s Project Moonshot is designed to dramatically reduce the energy, space and cost of conventional servers.
• Data center configuration – beyond the selection of efficient IT equipment, data centers inherently require mechanical systems to remove excess heat and moisture from the air to protect delicate electronics. Data center configuration has advanced significantly over the past decade to maximize airflow and employ sophisticated cooling technologies. Though cooling design and equipment should be selected on a case specific basis, the U.S. Department of Energy recently published a compendium of best practices on the topic. Additional DOE software tools and trainings are also available to help end users evaluate their data center’s energy use and identify energy saving opportunities.
• Onsite generation – onsite generation, often in the form of combined heat and power (CHP), is gaining traction in this sector.  Because data centers operate continuously at nearly constant loads, they are good candidates for CHP. Data centers can use the electricity from CHP systems for their electrical loads and the excess heat for thermally activated cooling systems (typically an absorption chiller).  
• Waste Heat Recovery – whether capturing excess heat from IT equipment alone, or in combination with thermal waste streams of onsite generation, it is possible to use otherwise wasted heat for productive applications. Depending on the “quality” of the heat, possible applications may range from space or water heating for a neighboring office building to powering onsite chillers for data center cooling.
• Direct Current – typically, data centers convert grid-supplied alternating current (AC) to direct current (DC) several times for the power going to the IT equipment. These conversions cause losses in electrical power. In some cases data centers can be reconfigured to rely on direct current only, which can reduce power usage 10% to 20%. However, capital costs to reconfigure data centers to DC power remain high.