According to research by Info-Tech Research Group, London, Ontario, Canada, 33% of North American companies with computer rooms or data center complexes completed a renovation of those areas in 2010. Among the cost considerations for those projects, cooling renovations cost an average of $87/sq. ft, with the median cost of cooling system renovations landing between $51,000 to $100,000. It can be money well spent, since cooling the data center can amount to about 50% of a data center’s operating costs, according to Info-Tech Research Group. (infotech.com)

Types of Computer Room Cooling Systems
For the largest applications, computer room air conditioners (CRACs) monitor and maintain the temperature, air distribution and humidity in a network room or data center. A CRAC delivers cool air to the servers, and pulls exhaust air from the room. One CRAC setup that has been successful is to cool the air and circulate it through an elevated floor. The air rises through the perforated sections, forming "cold aisles." The cold air flows through the racks where it picks up heat before exiting from the rear of the racks. The warm exiting air forms "hot aisles" behind the racks, and returns to the CRAC intakes, which are positioned above the floor.

Computer Room Air Handlers (CRAHs) are chilled water-based units installed on the data center floor and connected to an outside chiller plant. The CRAH circulates air throughout the data center through fans, delivers cool air to the servers, and returns exhaust air from the room.

Humidifiers are usually installed within CRAC and CRAH units. They replace water loss before the air exits the air conditioning units. Standalone humidifiers are also available.

Chillers produce chilled water and deliver it through pumps to the CRAH units.

Split systems can be used to cool multiple zones or rooms as wall mounts or ceiling-mounted cassette units.

Portable cooling units can be maneuvered to cool various areas, or can also be mounted

The distinction between computer room cooling and comfort HVAC can't be over-emphasized.

Because data centers are high-density, enclosed spaces that generate a significant amount of heat, traditional HVAC comfort cooling systems can't remove enough heat to protect the critical equipment.

"Precise temperature control in a data center is critical to maximizing availability and performance of essential equipment," says Marc Zipfel, director, product marketing, Mitsubishi Electric Cooling & Heating.

According to Zipfel, the Mitsubishi Electric R2- and Y-Series VRF systems are the best choices for data center applications because they can be used with Mitsubishi's low ambient cooling kit. Mitsubishi Electric's low ambient cooling kit provides 100% cooling at outdoor temperatures down to -10F, while still allowing full airflow at higher temperatures, and full heating capacity if necessary. The system hood moves its position automatically, and along with its INVERTER-driven technology, provides optimum airflow at lower temperatures.

Specially-designed wind deflectors block unwanted wind that could impede data center operation and, at the same time, allow airflow when required at higher temperatures.

Mitsubishi Electric's W-Series (Water-Source Series) can also be used in data centers. These systems are designed for buildings with closed loop boiler/water tower or geothermal loop systems and are extremely energy efficient. The W-Series systems use water as a heat exchange medium and are installed inside, rather than out. This innovation offers efficiencies that are independent of the outside temperatures and well-suited to cooler climates. Mitsubishi Electric's extensive CITY MULTI Controls Network (CMCN) is always expanding with updated controls to be more user-friendly and precise. The CMCN can manage up to 2,000 indoor units from a single networked PC. Every data center has its own unique characteristics and challenges, and the CMCN is designed to support most any temperature demand.

Zipfel says contractors need to realize that specifications are prone to change with the development of new technology housed in the data centers.

"Computer systems are becoming more compact, and data centers and server rooms are becoming smaller and smaller, resulting in more heat generated in a smaller space. When new computers or systems that might change the load requirements of the space are brought into a data center, the temperature settings can easily be adjusted with the CMCN to accommodate the new equipment's temperature needs," Zipfel says.

John Martin, marketing manager, Data Aire, Inc., Orange, CA, providers of precision air solutions, says new servers are faster and more powerful, but they also generate considerably more heat than older server models. Therefore, air flow management in the data center is of vital importance.

"Computer room cooling is definitely a specialized area. If you've never done it you can get into a lot of problems," Martin warns. He says a big trend on the cooling side has been to replace axial fans in CRAC units with plug fans (also known as backward-curved EC fans). Higher efficiency EC motors generate less heat, which must be taken into consideration when determining the net capacity of CRAC equipment. The less heat that's generated by the motor, the more net cooling capacity the CRAC produces, while using the same amount of power, Martin says.