Engineered Systems - October 2008 - (Page 42)

The 250 South Wacker building reportedly houses a first for American HVAC installations. That might sound exotic, but as you’ll see, the author delivers the story behind this retrofit in a matter-of-fact manner that belies the step forward taken by the owner and project team. Da beams may never be quite as popular as Da Bears in Chicago, but they’re bound to spread as other project embrace the concept’s advantages. BY THOMAS C. POSKO, P.E. T he active chilled-beam system installed at the 250 South Wacker building in Chicago is the first operational chilledbeam system in the country. The system uses less energy than traditional systems, since its fan horsepower requirements are very low, and the water systems do the majority of the comfort work. The system eliminates IAQ issues, since outside air (primary air) is delivered in constant flow to each chilled-beam unit. Also, a multiple of four times primary air is circulated in the room by the chilled beam. There are no drafts, hot/cold spots, or odors from construction glues, paints, etc., as issues for occupants to deal with. Maintenance personnel are happy with the system since there are no moving parts. Once construction adjusts and calibrates the system, maintenance has a coil to clean once per year. This downtown, 17 stories, 270,000-sq-ft, 50-year-old office building on the Chicago River underwent a full modernization to bring it up to today’s state-of-the-art office building standards. The subsequent HVAC system modernization included a perimeter chilled beam system — a first for the nation as well as the city. WHEN ‘PLAN A’ GOES AWRY The original perimeter HVAC system for the building was a wallmounted induction system with no condensate drip pans. At the start of the remodeling projects, it was decided to dismount the induction system, clean/patch coils, clean the rubber nozzles, and paint the 50year-old cabinets. It soon became obvious to the team that this option was, in fact, not an option at all. Soon thereafter, parts and pieces began falling apart regularly. In addition, because the building’s vision glass extended to the floor, other options needed to be considered. The team, Turner Construction Special Projects Group; AT Mechanical, Inc.; Bauhs Dring Seglin Architects; Windy City Representatives, the owner’s facility group; and the consulting engineer, Posko Associates, Inc., discussed, conducted preliminary engineering studies for, and priced out numerous options. The ceiling-active chilled-beam system, as presented by Mestek, Inc./Dadanco, seemed to fit the bill. The system uses minimum energy, has no moving parts, requires minimum maintenance, is ceiling-mounted, and met the construction budget. The only issue was that there were no example sites for the team to visit. In order to resolve this issue, the team reviewed a number of chilled beam units, analyzing construction, and installing the samples. Upon successful completion of this analysis, it was decided to proceed with the chilled beam design and installation by the team. The results are a system which looks great, functions perfectly, and satisfies the green / energy conservation goals of the project. THE SYSTEM Chilled-beam systems are primarily used for cooling, heating, and ventilating spaces where good indoor environmental quality and individual space control are desired. The units are connected to the ventilation supply air ductwork and the two-pipe heating and cooling system. 42 En gi neer ed S y stem s October 2008

Table of Contents Feed for the Digital Edition of Engineered Systems - October 2008

Engineered Systems - October 2008 Contents Editor’s Note Letters Back2Basics HVAC Challenge Case in Point Commissioning Building Automation HydroTech HVACR Designer Tips Special Insert: Engineer's Technical Library Fall 2008 Living Wild! Chilled Beams in Chicago Phoenix Convention Center: On The Rise Cold-Climate HVAC Challenges Humidification Strategies For Data Centers & Network Rooms Special Advertising Supplement: Tabb Talk Computers & Software Issues & Events Products Literature & Catalogs Glossary Classifieds Advertiser Index Tomorrow’s Environment

Engineered Systems - October 2008

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