1、2009 ASHRAE 201ABSTRACT ASHRAE TC9.9 “Mission Critical Facilities, Technology Spaces and Electronic Equipment” was established to create guidance on the environmental protection of such environ-ments in an energy conscious manner. Mission critical facili-ties take on many forms, including telecommun
2、ications central offices and data centers. The former are associated with over-head cooling, concrete slabs, network equipment, and DC power-plants whereas the latter are associated with raised floors, hot aisle/cold aisles, and AC-powered servers. The challenges associated with telecommunications a
3、nd data centers are the same in many respects but different in a host of others. The decade old approaches in the telecom indus-try do not work in the converged “Datacom” environment. Many telecommunications facility operators see a number of challenges, including introduction of high-density loads,
4、 unknown density limits for reliable operation during normal and catastrophic cooling outages, hot air recirculation issues as result of multiple equipment types, and varying levels of equipment robustness.Today there is no single industry group pulling together the ideas, resources, and challenges
5、of HVAC in different mission critical facilities. ASHRAE TC9.9 could play a key role in this work going forward. INTRODUCTIONToday the “Datacom” Industry consists of a diverse group of industry organizations, companies, services, standards, and technologies all competing in the open marketplace. The
6、 advancement of technologies is outpacing many of the indus-try standards organizations. Furthermore, there is a concurrent convergence of many of these technologies and services occurring across many companies, resulting in a host of chal-lenges that are not currently addressed by any one industry
7、organization. The net result of this rate of change and conver-gence is chaos for the end-user.The Telco industry has continued with their own stan-dards and industry organizations. However, the decade old approaches in the telecom industry do not work in the converged “Datacom” environment. Many op
8、portunities are being missed to leverage the available resources from the converging industries to avoid old lessons learned. The marketplace is no longer confined to the U.S. borders. The global marketplace needs to be considered as an important factor for most companies in the 21stcentury. However
9、, a global view introduces additional industry organizations and standards further complicating the matter. One more widely known industry standards organization that is common to Datacom companies, their associated challenges, and recog-nized around the world is the American Society of Heating Refr
10、igeration and Air-conditioning Engineers (ASHRAE). ASHRAE is the common denominator because it addresses one of the fundamental needs of any electronic hard-ware environment HVAC. HVAC protection of these envi-ronments envelops thermal, moisture, and contaminants which are all intended to provide a
11、reliable operating environ-ment, while doing so in an energy efficient manner. Even more important is the recognition that HVAC for Datacom environ-ments includes much more than the HVAC equipment itself. The HVAC system includes not only the HVAC equipment, but the network equipment cooling class (
12、EC Class or how the equipment moves the airflow through the cabinet or frame; see Figure 1), means of air distribution, and how the network equipment and room are configured (hot aisle/cold aisle or a Convergence of Telecommunications and Data CentersDavid V. Quirk, PEMember ASHRAEDavid Quirk is a s
13、enior engineer in the Network Compliance group of the Network Department at Verizon Wireless, Basking Ridge, NJ.LO-09-017 2009, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions 2009, vol. 115, part 2. For personal use
14、only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.202 ASHRAE Transactionsmixed environment with cooling in all aisles). If these compo-nents of the HVAC system dont mesh properly, the system will not
15、 perform at optimal efficiency or reliability.Today, mission critical facilities take on many forms, including telecommunication central offices, cellular mobile switching centers, cellular sites, VoIP data centers, cable TV communication centers, satellite communication centers, Internet Service Pr
16、oviders (ISPs), Application Service Provid-ers (ASPs), financial institution data centers, credit card data centers, IT data centers, web hosting facilities, and a host of others. Using traditional definitions, a tour of any mission crit-ical “Datacom” facility would leave many trying to explain wha
17、t the facility is and what it does. The traditional data center facility is most commonly associated with raised floors, hot aisle/cold aisle, high power densities, and rows of rack mounted servers that are AC powered. Conversely, the tradi-tional telecommunications facility is most commonly associ-
18、ated with overhead cooling, concrete slabs, lower power density, a different variety of network equipment consisting of routers, switches, gateways, tape drives, interconnect frames, and servers, as well as DC power-plants. In between, the industry is a melting pot of these extremes, combining eleme
19、nts from both industries (infrastructure and network services or functions). Its believed by some that the “melting pot” constitutes the majority of mission critical facilities currently and encompasses ISPs, ASPs, Telco hotels, cellular mobile switching centers, and a variety of other communica-tio
20、n and data processing centers. Telecommunications facility operators may see the following significant challenges as a result of these meshing technologies that may or may not be found in the more traditional data center:1. Introduction of high-heat dissipating Point Loads into low power density equ
21、ipment environments2. Unknown acceptable power density limits locally and overall such that reliability of network services wont be affected even during catastrophic cooling outages3. Hot air recirculation problems at cabinet levels as result of differing cabinet configurations, mixed Equipment Cool
22、ing (EC) Classes, mixed air distribution approaches (Vertical Overhead VOH vs. Vertical Under floor VUF), non-standardized hardware configurations and lack of blanking panel management/awareness. What are acceptable power density thresholds in such environ-ments? How are they integrated, migrated, a
23、nd managed towards a holistic solution?4. Varying levels of equipment standards, guidelines, and testing for environmental robustness NEBS GR-63-CORE (Telcordia, 2006), GR-3028-CORE (Telcordia, 2001), UL60950, PICMG ATCA, etc.5. Different equipment power supply options AC, low voltage DC, and high v
24、oltage DC powered equipment.6. Different set of standards and industry groups used to govern the design and/or construction of the infrastruc-ture and/or networkOne of the most significant underlying issues that impacts the holistic approach to HVAC design in “Datacom” facilities consists of the dis
25、aster recovery approach to the network services. The redundancy characteristics of the electronic equipment, facilities, and associated services have a direct and immediate effect on the HVAC approaches used to cool and protect the electronic equipment and to what levels. The Uptime Institute has pu
26、blished a document that provides guid-ance on the infrastructure redundancies through a “tier classi-fication system”, which touches on the network and electronic services topology (Turner, W. P. et al, 1996). Most companies performing HVAC design dont understand the importance of an owners network
27、or electronic systems topology, however, this would be a gross oversight that could lead to incorrectly designed infrastructure. For example, to not understand the network topology is akin to designing a building without understanding its intended occupancy the equipment is simply the occupant. Ackn
28、owledging the network topology may allow or require alternative infrastructure approaches. These alternative approaches could be significant when reviewing “green” approaches to minimizing energy and resources used to accomplish the stated objectives or the LEEDCredits sought after.Today, most if no
29、t all “Datacom” industries are converg-ing on scalable, energy efficient, IP based platforms in what will likely shape a unified, worldwide communication and information system in the future. In order for this convergence to be the most successful, there would be many advantages for a single industr
30、y organization to take the lead and pave the way with industry best practices and standards for a holistic approach to HVAC design, ensuring seamless integration and convergence. BUSINESS MODELSAll too often, the fundamental models and approaches used for mission critical facilities do not account f
31、or the differences Figure 1 Equipment cooling (EC) class (Telcordia, 2006).ASHRAE Transactions 203in the business models and network architecture. Practically speaking, design of any portion of the HVAC system should not occur until there is a clear understanding of these items; only then can approp
32、riate strategies for HVAC be considered. There are several important business model aspects that must be iden-tified and understood in advance of proper HVAC design as follows:Services being providedHow often those services can be interrupted or taken out of serviceNetwork and equipment architecture
33、 georedundant, fail-over, backup facility, etcCompany disaster recovery approachEquipment refresh rates and depreciation cyclesEquipment vendors used and the underlying industry Standards their platforms are designed or tested toPower approaches usedApplicable industry standards for that application
34、Company operational practicesEach of these has a direct affect on the HVAC design. Currently “Datacom” is covered by the same umbrella in terms of HVAC strategies presented. As mentioned before, mission critical “Datacom” facilities can be many things and each have unique challenges that must be ful
35、ly understood before applying a HVAC design. Furthermore, these items can vary amongst different companies within the same subset of a particular industry there is no “one shoe fits all” approach. The challenges facing many Telco providers exist due to the specific aspects of their business model, s
36、ome of which have changed over recent times and will likely continue to evolve. In order to understand the importance and value that a unified industry standards organization can bring to the table, its necessary to understand the different business models and how the industry convergence is causing
37、 significant challenges amongst all groups.Typical Data Center Business ModelData center facilities are often associated with raised floors, hot aisle/cold aisles (Figure 2), and servers that are AC powered. On one end they provide services for enterprise customers and serve as Application Service P
38、roviders, Inter-net Service Providers, and Web-hosting, to name a few. On the other end they are used for internal batch processing and IT functions. In these extremes, there is a notable difference between the acceptable interruptions to service. Some may argue that batch processing and IT function
39、s can be inter-rupted without significant harm to the public, the company itself, or the electronic equipment itself. On the other end of the spectrum, interruption to your credit card services could be severe. Fortunately, servers and the applications hosted on them lend themselves to geo-redundant
40、 auto fail-over func-tions, which can be utilized to avoid such failure conditions. Often times, companies with such equipment implement a disaster recovery approach which includes a backup facility or a redundant facility capable of providing the same services concurrently. In addition, the refresh
41、 rates for servers in data centers can vary significantly and may be as frequent as a couple years to once every 10 years or more, depending on a companys depreciation cycles and company strategy. For the vast majority of data center facilities, AC power is the predom-inant power source used consist
42、ing of UPS/PDU systems with 30 minutes or less backup power. Approaches to operations can vary widely and can consist of unmanned facilities on one extreme, with 24/7 operations of highly trained personnel on the other. The HVAC systems selected as well as the system design are largely dependent on
43、a clear understanding of the intended operational approach.Typical Telecommunications Business ModelTelecommunication facilities are most commonly associ-ated with overhead cooling, concrete slabs, lower power density, mixed cooling environments (Figure 3), a different variety of network equipment c
44、onsisting of routers, switches, gateways, tape drives, interconnect frames, and servers, as well as DC power-plants. All telecommunication facilities provide communication infrastructure and the “backbone” for many other Datacom companies to provide their application services. In their simplest form
45、, telecommunication facilities were historically the transport backbone for voice communi-cations. However, more recently they are also the transport backbone for a host of data communications. Many of these communication systems provide emergency services, which makes interruptions to service unacc
46、eptable for any period of time. Most of these facilities have end-points or “access” nodes to their networks to connect to the end-user, which means they typically have single points of failure and dont lend themselves to the same failover strategies often used in many data centers. The refresh rate
47、s for equipment in telecom is typically less frequent and for many historically, it was decades long. For the vast majority of telecom facilities, DC Figure 2 Hot and cold aisles.204 ASHRAE Transactionspower is the predominant power source used with one or more hours of battery backup. Again, approa
48、ches to operations can vary widely and can consist of unmanned facilities on one extreme, with 24/7 operations of highly trained personnel on the other. The HVAC systems selected as well as the system design are largely dependent on a clear understanding of the intended operational approach. Lastly,
49、 the Telecom industry has several of its own industry standards for the network equipment and infrastructure. In many instances these stan-dards are in conflict with current day data center industry prac-tices and they are slowing the implementation of these newer technologies into the Telecom world. An example of this would be how NEBS testing currently doesnt acknowledge liquid cooled electronic equipment (no test method exists).ISSUES ASSOCIATED WITH INDUSTRY CONVERGENCEAs mentioned before, many telecommunications facility operators see several significant cha
