Improving Data Center Cooling With Cold Aisle Containment

As the current demand for data processing and storage increases, so does the amount of heat produced within these facilities. Hotter temperatures in data centers require cooling systems, that incur further electricity costs. This has driven data center professionals to seek more efficient cooling solutions to manage rising temperatures within these facilities.

Aisle containment, either hot or cold, has been the solution of choice for most data centers. According to a 2007 study by Pacific Gas and Electric, reported by Gartner, aisle containment can reduce cool air operating costs by 20%. Furthermore, research conducted by Lawrence Berkeley National Laboratory in 2007 discovered that the electricity used to move cold supply air could be reduced by 75% with the adoption of cold aisle containment.

The Advantages of Cold Aisle Containment

Cold aisle containment evenly separates cold and warm air and can replace existing cooling systems. This containment method can be implemented fairly easily into any data center space and has the potential to reduce cooling-related energy costs by up to 30%, making it a cost-effective solution for data centers.

Comparing Conventional Cooling with Cold Aisle Containment

Typically, data centers rely on conventional cooling methods where cold air is circulated from computer room air conditioning (CRAC) units through a plenum under a raised floor. These CRAC units are typically located around the perimeter of the data center, outside the computer server rack rows. A hot aisle/cold aisle configuration is a best practice that has been widely implemented to enhance the efficiency of raised floor data centers. However, this conventional setup has its limitations. Hot air often mixes with cold air near the top of the racks and at the ends of cold aisles, resulting in unpredictable air temperatures that can be dangerously high for sensitive computer servers. Increasing the airflow in the cold aisles can help address this imbalance, but it also increases energy use, making it a less efficient solution.

Aisle containment offers a great solution to this problem as it prevents the mixing of hot and cold air streams. However, before installing aisle containment, certain basic measures must be implemented to enhance the cooling system’s overall energy efficiency.

Steps to Improve Cooling Efficiency

Contain the Data Center Environment

One of the first steps in improving cooling efficiency is to minimize the latent (moisture-related) cooling load by ensuring that the data center has a good vapor barrier and no leaks around doors, windows, or other openings. Minimizing the amount of outside air that can get in is also important. By sealing out moisture, the total available cooling can be more effectively used to cool the computer servers’ heat load, which is 100% sensible (no moisture content).

Better Optimize Airflow

There are several techniques to help optimize airflow within the data center:

• Arrange server racks in a hot aisle/cold aisle configuration: Most modern equipment is designed to draw air in through the front and exhaust the used air out the rear. This allows equipment racks to be arranged in a manner that creates hot aisles and cold aisles. In this setup, rows of racks face each other, with the front of each opposing row drawing cold air from the same aisle (the cold aisle), while hot air from two rows is exhausted into a hot aisle. This arrangement raises the temperature of the air returning to the CRAC unit, allowing it to operate more efficiently.
• Install blanking panels in and between racks: Blanking panels prevent hot air from circulating to the front of the rack where the electronic equipment air intakes are located.
• Place CRAC units correctly: Positioning CRAC units at the end of hot aisles reduces air travel and prevents hot air from being pulled down into the cold aisles as it returns to the air conditioner. Alternatively, the overhead plenum can be used for hot air return to the CRAC units.
• Seal the raised floor: Ensure there are no leaks at cable penetrations, perimeter penetrations, and raised floor tile joints.
• Minimize cables and pipes under the raised floor: Old cables can obstruct airflow. If cables must be present under the raised floor, they should be placed in the hot aisle running parallel to it.
• Minimize cables in the back of the rack: Using a cable management system within the racks prevents cables from obstructing the exhaust air from servers.
• Optimize perforated tile locations: Conducting a thermal assessment of the data center using computational fluid dynamics (CFD) is an effective way to determine the optimal locations for perforated tiles.

Adjust Air Supply Temperatures

In many data centers, raising the air supply temperature while still remaining within the ASHRAE recommendations of 64.4°F (18°C) to 80.6°F (27°C) reduces the overall energy required for cooling.

Follow Proper Operating Guidelines

Ensure that method of procedures (MOP) and other process documents covering maintenance, installation of new equipment, and other aspects of routine operation are current regarding energy efficiency and are followed meticulously.

Implement System Monitoring

Regular monitoring can predict necessary preventive maintenance actions, such as filter replacements, which help ensure that the cooling system operates efficiently.

Implementing an Aisle Containment System

Beyond these baseline measures, a data center can significantly improve energy efficiency by separating the hot and cold air streams through aisle containment. This involves sealing off the aisle so that cold air does not mix with warm air within the data center. Typically, this is achieved using ceiling panels above the aisle between adjoining racks and installing doors at the ends of the aisle. There are also less comprehensive approaches, such as pressurized aisles and plastic curtains. The pressurized aisle approach involves containment doors at the ends of the aisle and cooling modules located above or on top of the racks, which take hot air from the hot aisle, cool it, and supply cold air into the cold aisle. Plastic curtains, which must be fire code approved, can be installed at the ends of the aisle and between the top of the racks and the ceiling. While plastic curtains can separate hot and cold air, they are not as efficient as solid panels and doors.

Contact Cool Shield

For more information or to receive a quick quote on hot aisle or cold aisle containment, contact Cool Shield today.

Contact Information:
866-740-2121
cssales@cool-shield.com

Source Article:
Focused Cooling Using Cold Aisle Containment, https://www.vertivco.com/globalassets/shared/focused-cooling-using-cold-aisle-contaiment.pdf (PDF, 582 KB)