Data center environmental control

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Data center at CERN. The rear of the equipment racks are exposed to the room while the aisles containing the fronts of the servers are enclosed with doors and covers, indicating cold aisle containment is being practiced.

Data center environmental control is a constructive generic framework for maintaining temperature, humidity, and other physical qualities of air within a specific range in order to allow the equipment housed in a data center to perform optimally throughout its lifespan.

Air flow[edit]

Air flow management addresses the need to improve data center computer cooling efficiency by preventing the recirculation of hot air exhausted from IT equipment and reducing bypass airflow. There are several methods of separating hot and cold airstreams, such as hot/cold aisle containment and in-row cooling units.[1]

Overheating of data center equipment can result in reduced server performance or equipment damage due to hot exhaust air finding its way into an air inlet. Atmospheric stratification can require setting cooling equipment temperatures lower than recommended. Mixing the cooled air and exhausted air increases refrigeration costs.


IT vendors[who?] recommend maintaining temperature of 70–75 °F (21–24 °C). The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) states that the recommended temperatures is between 68–77 °F (20–25 °C), with an allowable range spanning 59–90 °F (15–32 °C). Research has shown, however, that the practice of keeping data centers at or below 70 °F (21 °C) may be wasting money and energy.[2] Overcooling equipment, in environments with a high relative humidity, can expose equipment to a high amount of moisture that facilitates the growth of salt deposits on conductive filaments in the circuitry.[3]

Although a high cooling temperature is more efficient, overcooling of smaller server rooms can provide reserve thermal protection in the event of cooling system failure, or in outage situations where the computers are provided emergency backup power but cooling systems are not. In such situations, the equipment can continue to run and tolerate several degrees of temperature rise before system damage from overheating occurs. Environmental reserve cooling capacity may not be feasible in dense equipment environments such as datacenters, but those locations are more likely to have backup cooling and emergency power for cooling.

Data center operators should also monitor the difference between intake and outtake temperature within their racks. The temperature delta may not exceed 20 °C or 35 °F.[4]

Summary of vendor datacenter temperature recommendations
Vendor Low (C°/F°) High (C°/F°) Optimal
ASHRAE[5] 18/64.4 27/80.6 -
Enviromon[6] 18/64.4 27/80.6 -
Avtech[7] 20/68 24/75 -
Cisco[8] 18/64.4 27/80.6 -
Google[9] - - 26.7/80
Dell[10] 24+/Upper 70 F° 26+/Lower 80 F°
HP[11] 18/64.4 27/80.6
IBM[12] 18/64.4 27/80.6
ServersCheck[4] 18/64 27/80 -
Oracle[13] 21/70 23/74 22/72

Rack hygiene[edit]

Blanking plates and other fittings around the edge, top, floor, or the rack direct air intake so that only air from the cold aisle reaches equipment intakes and prevent leakage of exhaust air into the intake area. Fans on the top or rear doors of the cabinet ensure a negative pressure for exhaust air coming out of equipment. Effective airflow management prevents hot spots, which are especially common in the top spaces of a rack, and allows the temperature of cold aisles to be raised.

Aisle containment[edit]

Typical cold aisle configuration with server rack fronts facing each other and cold air distributed through the raised floor.

Containment of hot/cold aisles and ducting hot air from cabinets are intended to prevent cool and exhaust air from mixing within server rooms. Rows of cabinets are paired to face each other so that cool air can reach the equipment air intakes and warm air can be returned to the chillers without mixing with the cold air supply. A more recent addition to the consideration of above floor containment is below floor air flow control. A range of underfloor panels can be fitted within the raised floor plenum to create efficient cold air pathways direct to the raised floor vented tiles.

Containment is generally implemented by physical separation of the hot and cold aisles, using blanking panels, PVC curtains or hard panel boards. Containment strategies could differ based on various factors including server tolerance, ambient temperature requirements and leakage from data centers. Either the cold aisle or the hot aisle can be contained.[14]

An alternative method of containment that has gained popularity in the past few years is the equipment cabinet with vertical exhaust duct (chimney)[15] The hot exhaust air that is given off by the servers exits the cabinet through the vertical exhaust duct, directing the air into a plenum above a drop ceiling and back to the cooling units or to outside vents, isolating the hot air from the room. With this configuration, traditional hot/cold aisle configuration is not a requirement[16].

Access floor[edit]

The type of floor a facility uses can also greatly affect its air flow capabilities and limitations. Specifically, a raised floor allows for under-floor cable management as well as air flow. There are two main classifications of such access floors: low-profile floors (under 6 inches in height) as well as standard/traditional access floors (over 6 inches).[citation needed]

See also[edit]


  1. ^ Fox, Mike (2012-02-15). "Stulz announced it has begun manufacturing In Row server cooling units under the name "CyberRow"". DataCenterFix. Archived from the original on 1 March 2012. Retrieved 27 February 2012. 
  2. ^ Cosmano, Joe (2009), Choosing a Data Center (PDF), Disaster Recovery Journal, retrieved 2012-07-21 
  3. ^ Garrett, David (2004), Heat Of The Moment, Processor, archived from the original on 2013-01-31, retrieved 2012-07-21 
  4. ^ a b ServersCheck. "Best Practices for data center monitoring and server room monitoring". Retrieved 2016-10-07. 
  5. ^ "BSR/ASHRAE Standard 90.4P Energy Standard for Data Centers" (PDF). ASHRAE. 2016-01-01. Retrieved 2017-03-22. 
  6. ^ "What Should My Server Room Temperature Be At?". Retrieved 2017-03-22. 
  7. ^ "An Updated Look at Recommended Data Center Temperature and Humidity". Retrieved 2017-03-22. 
  8. ^ "Data Center Power and Cooling white paper" (PDF). 
  9. ^ "Efficiency: How we do it – Data Centers – Google". Retrieved 2015-08-01. 
  10. ^ "Data Center Operating Temperature: The Sweet Spot" (PDF). 
  11. ^ "Applying 2011 ASHRAE data center guidelines to HP ProLiant-based facilities" (PDF). 
  12. ^ "Environmental design criteria". Retrieved 2015-08-02. 
  13. ^ "C H A P T E R 2 - Environmental Requirements". Retrieved 2015-08-02. 
  14. ^ Hot-Aisle vs. Cold-Aisle Containment for Data Centers, John Niemann, Kevin Brown, and Victor Avelar, APC by Schneider Electric White Paper 135, Revision 1
  15. ^ "US Patent Application for DUCTED EXHAUST EQUIPMENT ENCLOSURE Patent Application (Application #20180042143 issued February 8, 2018) - Justia Patents Search". Retrieved 2018-04-17. 
  16. ^ "Airflow Management Basics – Comparing Containment Systems • Data Center Frontier". Data Center Frontier. 2017-07-27. Retrieved 2018-04-17. 

Further reading[edit]