Data centers are very different from offices, and therefore impose very different requirements on a building management system. Yes, there is a need to control lighting, power, environmental conditions and security in a data center just as there is in an office building.
But in "lights out" data centers, the power must be clean and continuous, and temperature and humidity settings are determined by the equipment rather than human comfort. Perhaps the biggest difference, though, is that the building management system is operated by the Facilities department, while the data center is under the control of the IT department. This makes it difficult, for example, for the data center to participate in an organization’s demand response and energy conservation initiatives.
While we explore how IT and facilities departments can cooperate to better manage all of an organization’s energy consumption, it is necessary to introduce a type of building management system (BMS) purpose-built for the special needs of the data center: the data center infrastructure management (DCIM) system. Whereas office building management is focused on the working conditions created by the facility's heating, cooling and lighting, the DCIM system focuses on the building, power and cooling, and the IT/server capacity in an integrated fashion to optimize the building as application demand goes up and down.
There are several ways IT and facility managers can work together to minimize energy consumption in the data center whether the data center is collocated in an office building or has its own, dedicated facility. Among the most common initiatives are:
- Right-sizing the uninterruptible power supply (UPS) and power distribution equipment to minimize inefficiencies
- Making greater use of outside air and/or thermal storage for cooling
- Eliminating cooling inefficiencies and/or upgrading the computer room A/C system
- Adopting a hot/cold aisle configuration, and increasing cold aisle inlet temperatures to 80°F (27°C) as recommended by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
Improvements in these areas can be measured by the DCIM system using the Power Usage Effectiveness (PUE) metric. PUE is the ratio of total power consumed and the power used by the IT equipment. Today's typical data center achieves a rating of about 1.8 to 1.89 according to the latest report from the Uptime Institute, which means that just a bit over half of the total power consumed is being used by the IT equipment (servers, storage and networking infrastructure), with the other half going mostly to the cooling and the inherent inefficiencies in power distribution systems.
The Environmental Protection Agency has established a target for data centers in the U.S. of a PUE rating between 1.1 and 1.4. The benefit in reaching this target range can be profound; for example, an improvement in PUE from 2.3 to 1.3 nearly doubles the power available for IT equipment, thereby extending the life of the data center.
Next page: Achieving optimal power consumption