Small Data Centers

Data Centers consume about over 70 billion kWh of electricity yearly, 2% percent of the total, with increasing numbers of users as more information is shared and stored online. Energy efficiency potential exists with small data centers, defined as under 5,000 square feet of computer floor space; these centers house over 50 percent of all servers and consume about 40 billion kWh per year.

small data centers lack the resources to implement energy-saving opportunities

Energy Efficiency measures achieve savings of 20 to 40 percent without impacting IT equipment reliability, when properly implemented.

Unused Servers an estimated 20-30 percent of servers in data centers are consuming power, cooling, and space while not working; idle servers consume half the power as at full load. To better manage server usage and utilization, create and update a server hardware and application inventory that tracks the number of applications running on each server.

mapping applications to the physical servers helps identify unused servers

Power Management saves energy by turning off power or switching equipment to low-power modes when not in use. Energy Star servers are shipped with three categories of power management enabled. Utilize built-in or add-in cards that enable servers to be powered on or off remotely. Improve air management; the key task is to ensure that cool air from the data center’s cooling equipment gets to the air inlet of the IT gear, without getting mixed with the hot air exhausted from the back; also ensure that hot air going back to the cooling equipment does not mix with the cold air. This is achieved by clearing clutter from the desired airflow path, blocking off bypass and recirculation airflow paths within and between the racks and the raised floor.

Energy Savings can be realized through two measures: raising temperature setpoints and reducing air-flow rates. There is a broad range of air-management strategies that span the range of complexity and cost; containment of cold or hot aisles is a very effective approach as is increasing temperature setpoints to deliver air towards the high end of the ASHRAE recommended range; temperature guidelines allow much broader operating ranges than those commonly used, allowing the air temperature at the IT equipment inlet to be raised-up to 80°F or higher- which considerably reduces cooling energy usage compared to the inlet temperatures of 65-70°F commonly used.

Computer-Room Air Conditioners (CRACs) and Computer-Room Air Handlers (CRAHs) control their temperatures based on return air; these CRAC/H setpoints will be much higher than the IT inlet temperature. In chilled-water systems, if raising the air temperature also enables raising the chilled water temperature, a 1°F rise in the chilled water temperature typically results in a 2 percent reduction in chiller energy.

Active Humidity Control energy savings can result from reducing humidification and the over-cooling and reheat typically involved in active dehumidification. ASHRAE humidity guidelines, expanded on the low end to about 8 percent relative humidity, allow much broader operating ranges than those commonly used. As a result, large energy and water savings are possible by eliminating this control.

Uninterruptible Power Supply UPS requirements. Risk-averse IT managers often overdesign redundancy into their systems, when in fact many IT applications can be shut down if there is a power disturbance and restarted without adverse effects. Verifying power backup requirements can help eliminate capital costs for unnecessary or oversized redundant power supplies or UPS equipment.

high reliability items should move to larger data centers or cloud solutions

Establish server refresh policies that account for increases in generation-on-generation computational ability, energy -efficiency, and power management improvements. When purchasing new equipment, servers with solid-state drives SSD, rather than hard disk drives, could be considered, as they feature faster speeds, are generally more reliable, and consume less power. New equipment typically has much more computing power than older equipment, which facilitates consolidation and virtualization. Consolidate and Virtualize Applications typical servers in server rooms and closets run at very low utilization levels - 5-15%, while drawing roughly 75 percent of their peak power on average. Consolidating multiple applications on a smaller number of servers accomplishes the same amount of computational work, and the same level of performance, with much lower energy consumption. Virtualization consolidates applications, allowing multiple applications to run in their own environments on shared servers. Increasing server utilization reduces both the number of servers required to run a given number of applications and overall server energy use.

Distributed Server Rooms are typically not very energy efficient. If a central data center is available, you may be able to save energy and reduce your utility bill by moving your servers, or their applications, to that location. Many organizations are moving their equipment to co-location or their applications to cloud facilities

co-location and the cloud provide better efficiencies than on-premise server rooms

Power Monitoring identifies the energy use and efficiencies of the various components in the electrical distribution and cooling systems. While power monitoring by itself will not save energy, it can help identify energy saving opportunities. Power meters can be installed at the panels serving the cooling units, or directly on IT and HVAC equipment. Often power distribution products will have built-in monitoring capability.

Air-side Economizers draw in outside air for cooling when conditions are suitable.  Server rooms with exterior walls or roof are a pre-requisite for air-side economizers. This could be in the form of an exhaust fan removing heat in one portion of the room and an opening in another location allowing cool, outside air to enter; alternatively, it could be in the form of a fan coil or CRAC/H with air-side economizer capability. Depending on the climate zone in which the server closet is located, this strategy can save a significant amount of energy by reducing compressor use needed for cooling.

Training is important to keep up with the rapid evolution of technologies and solutions in the data center sector; skills are required to perform accurate data center energy assessments. The Data Center Energy Practitioner DCEP training program certifies energy practitioners qualified to evaluate the energy status and efficiency opportunities in data centers. The program reinforces best practices and introduces new tools and techniques in IT equipment, air management, cooling systems, and electrical systems. 

                                                     Saving Energy in Your Data Center

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