Engineered Systems - April 2008 - (Page 56)

Environmental control in critical facilities faces a few hurdles, but here’s one you don’t hear much: We just haven’t been doing it that long. Learning about real effects of different conditions on equipment is another key to saving energy and avoiding design overkill. As the author explains, a little context balanced with a commitment to precision criteria will go a long way in this environment. BY WILLIAM J. KOSIK, P.E., CEM, LEED® AP umidity control in data centers and other critical facilities, where the regulation of the environmental conditions is essential to the successful outcome of the process, is one of the more misunderstood aspects of the HVAC design for these buildings. Why is this? Addressing the following points will help clarify the issues. So, relative to when A/C systems were first used, providing environmental control in a data centers is still in its early stages of development. With this said, it is understandable why there are still many gray areas that have not yet been standardized, especially with the overlay that computer technology itself continues to evolve at a very rapid pace. As early researchers and inventors of A/C processes and equipment discovered, adding or removing moisture to or from the air in a data center (or any other facility type) is inextricably linked to the cooling process. Changing the moisture content or the temperature of the air requires energy. The amount of electricity (or other fuel source) that is required depends not only on the efficiency of the equipment, but also on the basic design criteria being used. Although there is now a substantial amount of valuable design information on cooling systems for data centers, rules of thumb and outdated design criteria are still too often used (especially in the early conceptual design phases), leading to incorrect design assumptions and approaches which will often hinder the performance of the data center and increase power usage. (Note: This is not meant as an indictment of HVAC designers who do not specialize in data center cooling techniques, but rather a challenge to those who do — they need to continue to work toward the development of best practices in design, commissioning, and operations of data center cooling systems, which will benefit everyone involved.) POINT 2 THE REAL EFFECT ON EQUIPMENT More data is required on the failure mechanisms of electronics due to temperature and humidity levels (including both steady state and H POINT 1 THE GREAT UNKNOWN Cooling of computers and other sensitive electronic equipment is still a niche industry; further commercialization of techniques and products is required. Interestingly, one of the first commercial applications for A/C came in 1906 and was used for simultaneously maintaining temperature and humidity for a printing operation (not too far afield from modern-day data processing). After then, up until the middle of the century when demand grew for the use of A/C for comfort cooling applications, it was used for industries such as textiles, food processing and packaging, film processing, and other processes where fluctuations in temperature and humidity could have adverse effects. Challenges in cooling electronic equipment started in the 1960s1 with the advent of electronic data systems used in first in military applications and space exploration, and later in banking and financial processing. Development of standards and design techniques for cooling electronics using commercially available environmental control equipment has continually been refined in the last 20 years. However, the most significant advances in reliability, power efficiency, and dealing with high-density computer installations have really only occurred in the last 10 years2. 56 En gi neer ed S y stem s April 2008

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Engineered Systems - April 2008 Contents Editor’s Note Back2Basics HVAC Challenge Case In Point Commissioning Building Automation Energy Wiz HVACR Designer Tips This Time, Water Cooled Was All Wet Cleanroom Design In 10 Easy Steps It's Not The Heat, It's The Humidity Issues & Events Computers and Software Products Glossary Classifieds Advertiser Index Tomorrow’s Engineer

Engineered Systems - April 2008

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