Engineered Systems - June 2008 - (Page 55)

At first glance, what you see is a fine job with a complex peforming arts center ventilation design. However, cast your eyes a little further around this California campus, and the story gets into fuel cells and sophisticated thermal energy metering. Add the CFD modeling used by the engineers, and you’ve got a thorough design for the auditorium and surrounding spaces deserving of a curtain call. BY EDWARD D. CLEMENTS, P.E., LEED® AP I n the world of HVAC design and construction, there are few building types with as many specific intricacies in the design as higher education performing arts centers. For HVAC designers working on this unique type of facility, there is a mantra: the system has to be quiet. At the same time, it has to be efficient. In the best of designs, it’s both of the above while being essentially invisible, and best yet, inexpensive. The astute reader will realize that at least one of those points is usually contradictory to the rest. The struggle between the differing needs of performing arts HVAC systems is at times both the biggest challenge in and greatest reward from the design process. Feeling the comfort of a well-designed performing arts center HVAC system while not being able to see or hear it in action is the best reward for the designers of these systems. This article is a case study of some of the complexities encountered in the design of the Valley Performing Arts Center at California State University, Northridge. The performing arts center project is currently under construction, with an expected completion date of early 2010. Its 168,000 sq ft include a 1,600-seat proscenium theater/ concert hall, a 300-person black box studio theater, and support spaces including dressing rooms, green room, scene shop, costume shop, recital spaces, multi-use classroom spaces, administrative offices, and a full campus radio station. The facility will be erected at the southeast corner of a large, spread out campus, on a prominent corner, as the first building people will see as they approach from the east. CAREFUL CONSIDERATION The California State University (Northridge) campus has a pair of interconnected central utility plants, serving buildings with chilled and hot water. While not part of the performing arts center project, the design of the utility plant for the campus is of note in its focus on energy efficiency and sustainability. The chilled water system includes four main chillers located in two different satellite plants on either end of the campus. The chillers supply water to a large chilled water thermal storage tank. During all but the hottest summer days, the entire campus chilled water need is met by the storage capacity from the storage tank. The storage tank is recharged at night, when the campus gets a substantial break in its electric rate from the local utility. To further reduce energy use and operating costs, the campus uses a high (25°F to 30°) supply-return chilled water temperature differential to minimize the water volume flow rate through the campus, saving both pipe material cost and transport energy. Maintaining such a high temperature differential presented a design challenge for the performing arts center project. It required unusually careful equipment and coil selections; especially under part load conditions, a high coil temperature differential results in low flow rates that can yield laminar flow conditions within the coil. Laminar water flow within coils has been shown to result in a substantial decrease in heat transfer capacity. A drop-in coil-delivered capacity could result in a loss of control of cooling and dehumidification at part-load conditions, which make up the majority of the hours during the year. The central hot water utility has also recently undergone an expansion, which focuses on delivering heating water to buildings using susw w w. esmag a zin e. c o m 55

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Engineered Systems - June 2008 Contents Editor’s Note Letters To The Editor Back2Basics HVAC Challenge Case In Point Commissioning Efficiency Incentives HydroTech Building Automation Energy Wiz HVACR Designer Tips Notre Dame Tackles the Heat State Of The Arts Time For A Transplant? Project Delivery: What Can IPD Do For You? Issues & Events Computers & Software Products Application Checklist Glossary Classifieds Advertiser Index Tomorrow’s Engineer

Engineered Systems - June 2008

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