Hot aisle and cold aisle containment are the fundamental data-center energy efficiency solutions. My peer, Mike Peterson and I have covered containment in several previous blogs.
As business increasingly relies on the data center to create and drive business, power densities are increasing also. Data Center managers look to support higher power density, increased cooling demand, while searching for solutions to keep operating costs down and service levels high. This post will present a fresh look at cooling strategies, in terms of the degree of control offered at the room, row, and cabinet level and the how and when to apply them to provide energy efficient solutions for your business needs.
There are three basic approaches to directing airflow in the data center:
Hot aisle/cold aisle has been the industry default layout with cabinets aligned to create aisle for supplying cooling and heat removal. This is a best effort, brute force or flooding of air to cool equipment is one of the least effective ways to support an energy efficient data center.
Aisle-containment systems enclose and isolate either the hot aisles or cold aisles from the rest of the room. Separation or prevention of mixing is the goal. Both methods direct the air to the correct inlet: cool air to the IT server inlet and hot exhaust to the CRAC return. The system uses either curtains or doorways at the end of the aisle and a roof or vertical partition between the top of the cabinet to the finished ceiling. The use of both vertical and horizontal blanking panels is needed to prevent bypass air through the cabinet. Another component for successful implementation is airflow management devices to channel the air to the proper inlet of ‘side breathing’ IT equipment.
Aisle containment is appropriate for medium- to high-density power applications up to 10kW of power per rack. Both methods improve the energy efficiency of existing installations and evenly apply cooling to the equipment without overly impacting the surrounding room temperature. There have been several studies stating there is not a difference in energy savings using either method. Either are a great method of boosting energy efficiency and supporting higher power loads in cabinet.
Rack-containment systems allow finer control over the airflow that services each cabinet. Chimneys attached to individual cabinets evacuate exhaust air via the plenum ceiling or duct work to the CRAC system return. If used throughout the data center, rack-containment systems are ideal and provide maximum flexibility. Rack containment systems can handle densities of 8 KW to 30KW per rack. Applying a chimney solution to higher power racks will eliminate hot spots and avoid the costly addition of more cooling capacity. This solution is ideal for retrofitting an existing installation and can be applied on an as needed basis.
Belden provides two solutions to fit your needs. The passive system is recommended for heat loads of 3-8 KW. It directs the hot air via an enclosed pathway; allowing the fans in the servers and CRAC units along with natural convection to remove the hot exhaust air and preventing mixing.
For higher heat loads of 8-30KW, Belden recommends its’ active system or Adaptive Enclosure for Heat Containment (AEHC). It directs hot air like the passive system; but, its’ intelligent controller, based on air pressure sensors, adjust the CFM of the redundant, variable-speed fans to assist the removal of higher heat loads. As the air pressure created by the IT equipment exhaust varies, the controller varies the redundant fans directing the air back to the CRAC return automatically. The data center manager easily creates a symbiotic environment between the temperature of the supplied cold air at the inlet, IT equipment fan speed, and removal of hot exhaust. The dynamic nature of the system adjusts for changes in inlet temperature, equipment CFM, and AEHC to provide the highest energy savings and AEHC is SNMP compatible so it can be used with most DCIM monitoring solutions.
There is no universal “one-solution-fits-all” answer to address cooling and energy efficiency in the data center. There are many factors to consider prior to making a containment choice, so contact the experts at Belden to help you take a holistic approach to your entire Data Center environment for a recommendation that suits the needs and goals of your business.
Mike Salvador is a 28-year industry veteran, living the challenge of operating efficient data centers, optimizing the performance of network devices and delivering highly available, highly agile, low-risk data centers. Mike served as Belden’s technical solutions manager from 2012 to 2015.