Data Center

©2008, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission.

2008 ASHRAE Environmental Guidelines for Datacom Equipment -Expanding the Recommended Environmental EnvelopeOverview:The current recommended environmental envelope for IT Equipment is listed in Table 2.1 of the 2004 referenced ASHRAE Datacom book [1]. These recommended conditions as well as the allowable conditions refer to the inlet air entering the datacom equipment. Specifically, it lists for data centers in ASHRAE classes 1 and 2 (refer to the referenced ASHRAE book for details on data center type, altitude,recommended vs allowable, etc.) a recommended environment range of 20 to 25 oC (68 to 77 °F) (dry bulb temperature) and a relative humidity (RH) range of 40 to 55%. (See the allowable and recommended envelopes for class 1 in the psychrometric chart below.).

These environmental envelopes pertain to air entering the IT equipment

To provide greater flexibility in facility operations,particularly with the goal of reduced energy consumption in data centers, TC 9.9 has undergone an effort to revisit these recommended Equipment Environmental Specifications, specifically the recommended envelope for classes 1 and 2 (the recommended envelope is the same for both of these environmental classes). The result of this effort, detailed below, is to expand the recommended operating environmentenvelope. The purpose of the recommended envelope is to give guidance to data center operators on maintaining high reliability and also operating their data centers in the most energy efficient manner. The allowable envelope is where IT manufacturers test their equipment in order to verify that the equipment will function within those environmental boundaries. Typically manufacturers will perform anumber of tests prior to announcement of a product to verify that their product meets all the functionality requirements within this environmental envelope. This is not a statement of reliability but one of functionality of the IT equipment. However, the recommended envelope is a statement on reliability. For extended periods of time, the IT manufacturers recommend that data center operators maintain©2008, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission.

their environment within the recommended envelope. Exceeding the recommended limits for short periods of time shouldnot be a problem, but running near the allowable limits for months could result in increased reliability issues. In reviewing the available data from a number of IT manufacturers the 2008 expanded recommended operating envelope is the agreed-upon envelope that is acceptable to all the IT manufacturers, and operation within this envelope will not compromise overall reliability of the IT equipment.The previous and 2008 recommended envelope data is shown in table 1.

Low End Temperature High End Temperature Low End Moisture High End Moisture

2004 Version 20°C (68 °F) 25°C (77 °F) 40% RH 55% RH

2008 Version 18°C (64.4 °F) 27°C (80.6 °F) 5.5°C DP (41.9 °F) 60% RH & 15°C DP (59 °F DP)

Table 1 Comparison of 2004 and 2008 recommended operating envelope Neither the 2004 nor the 2008recommended operating environments ensure that the data center is operating at the optimum energy efficiency. Depending on the cooling system design and outdoor environmental conditions there will be varying degrees of efficiency within the recommended zone. For instance, when the ambient temperature in the data center is raised, the thermal management algorithms within some datacom equipment will...