Data Centers, Telecommunications Facilities Handbook Chapter Sees Another Round of Extensive Updates

 From eSociety, April 2019

By: Robert E. McFarlane, Member ASHRAE
Handbook Chair for TC 9.9, Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment
Voting Member for SSPC 90.4, Energy Standard for Data Centers

Data center technologies change so rapidly that extensive updates are needed on the four-year Handbook cycle.

The “Data Centers and Telecommunications Facilities” chapter in the 2015 ASHRAE Handbook—HVAC Applications was totally rewritten to correspond with the Datacom Series from TC 9.9, Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment.

The 2019 update to the Handbook continues to follow that format.  

Since the 2015 Handbook, two new books in the Datacom series have been published, bringing the total to 13. This information is summarized in Chapter 20, which was formerly Chapter 19.

Server Efficiency – Metrics for Computer Servers and Storage, consolidates information on current server and storage subsystem energy benchmarks.

IT Equipment Design Impact on Data Center Solutions, provides guidance in making data center infrastructure equipment selections and design configurations.

Three other books in the Datacom series have been revised with new editions published. This information is now included in the Handbook chapter.

Thermal Guidelines for Data Processing Environments, 4^th Ed., includes the dramatically expanded humidity range resulting from ASHRAE research. This proved far lower humidity levels can be maintained than have been industry practice for decades without concern about static generation and discharge.  

The resulting change in the thermal envelope provides opportunities for enormous energy savings. Both tabular and psychometric chart formats of the new ranges are included in the revised chapter.

IT Equipment Power Trends, 3^rd Ed., now extends to 2025 based on the latest information from leading datacom equipment manufacturers to help datacom facility designers more accurately predict future equipment loads.  

The growth rate charts and graphs in the Handbook chapter are more complete than in previous editions.

Liquid Cooling Guidelines for Datacom Equipment Centers, 2^nd Ed., includes a revised table showing new liquid cooling classifications and temperatures, made necessary by the steadily climbing rack heat loads which air cooling can no longer handle in a growing number of high performance and high density data centers.

One of the most significant changes is the inclusion of ANSI/ASHRAE Standard 90.4, Energy Standard for Data Centers. The standard was published in 2016 and has been updated with two addenda.  

Written as a non-prescriptive “sister” to Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, it provides new metrics for assessing data center energy efficiency in the design stage.  

This ensures that the best available practices can be used consistent with achieving reliability within the space, climate and budget realities of the project, and easily demonstrated to the AHJ.

Next, the issue of contamination has also been updated to reflect ASHRAE-sponsored research, showing that silver corrosion is a better indicator of gaseous contamination effects than the previously accepted method of copper corrosion. This is a very significant difference for data centers located where air pollution and humidity are high.  

Also noted are concerns about particulate contamination from suspended ceilings and zinc whiskers formed on electro-galvanized metals, particularly when used in air return plenums.

The following updates have been made and included in the chapter:

• Emphasis on raised access floors has been reduced, particularly as a means of conveying cooling air, although it does recognize newer types of airflow tiles and dampers. Further considerations are added for overhead infrastructure installations, particularly regarding ducted air delivery. The importance of CFD modeling of air flow design has been emphasized, along with cautions about the limitations of modeling, particularly if not done by experienced users.
• There is an expanded discussion of backup power systems, with lithium-Ion batteries added as a consideration for UPS systems.
• There are also precautions about the exposure of backup generators, primary switchgear and busduct to natural disasters.
• Extreme density hard disk drives have become more vulnerable to vibration, which can be from other equipment or gas fire protection discharge.
• Information on both LED and PoE-driven lighting has also been added to further energy efficiency.
• Information on use of the Power Utilization Efficiency or PUE™ metric developed by The Green Grid has been expanded, as well as on their Water Utilization Effectiveness or WUE™ metric, since water availability is becoming a greater concern in more regions.
• And lastly, the chapter expands the discussion of economizers, particularly adding information on the new refrigerant-side economizer option.