From the beginning of the project, the Massachusetts Green High Performance Computing Center project team aimed to reduce the energy intensity of the computing center. The following energy conservation measures were vetted during the design process and implemented as part of the MGHPCC.
Chillers are typically the most energy-intensive equipment in a data center. The MGHPCC therefore uses “free cooling” to minimize the amount of time that its chillers are in use. When the outdoor temperature is low enough, we can turn the chillers off and use water from the cooling towers to cool the computer room. In New England, were we only have hot weather for a few months each year, the MGHPCC can leave its chillers off more than 70% of the time.
Hot Aisle Containment
Hot aisle containment increases cooling efficiency by reducing the distance between the computers and the cooling units to less than 2 feet. It also prevents hot air generated by the computers from mixing with cold air from the cooling units, which further improves efficiency.
Raising the computer room temperature
Until recently, it was common to maintain “meat locker” temperatures of 70ºF or below in a data center. Today, 80º is the norm for data centers that use modern servers and hot aisle containment to improve cooling efficiency. That gives the MGHPCC more days of free cooling, further reducing energy use.
Monitoring and Control
The operation of every element of the cooling system is continuously monitored and adjusted so that it is delivering just enough cooling to keep each area of the facility within its operating temperature and humidity range. In the computer room, the cooling units in the hot aisle containment pods are networked to one another so that they can react within seconds to changes in cooling load.
Computational fluid dynamics (CFD) models CFD models of the air flow within a hot aisle containment pod made it possible for designers to verify the placement of the cooling units and check their performance in various failure scenarios. It also helped to identify improvements to the mechanical design and operation of the hot aisle containment pods that reduced susceptibility to air leaks that would otherwise have reduced the efficiency of the cooling system.
Optimized Power Distribution
The MGHPCC uses a high voltage power distribution system, which increases efficiency while operating within voltage ranges that are supported by all modern computing equipment. Higher distribution voltages mean lower current for the same amount of power, which reduces energy loss and heat generation in the wiring. Higher distribution voltages also make it possible to eliminate an entire tier of transformers from the facility, which reduces energy lost to power conversion, saves space, and reduces capital cost.
Another important source of energy loss in many data centers is the Uninterruptible Power Supply units that keep the facility running in the event of sudden loss of utility power. Many UPS units consume significant amounts of energy by doing a “double conversion” when they are not in use. The MGHPCC uses UPS technology with an operating mode that eliminates this kind of loss with no impact on performance.
Efficiency and Comfort in Work Areas
Sensors are installed in all spaces to turn the lights on or off based on actual occupancy, and daylight sensors in the offices and meeting rooms adjust the lighting up or down in response to the amount of supplemental sunlight entering the space. Occupants in the office areas are able to adjust airflow to meet their needs with individualized controls.