Engineered Systems - August 2008 - (Page 26)

GLASS BOX TO GRAND CASINO expect for a casino, and the timeline was very tight since the owners wanted an operating facility as quickly as possible. THE OPTIONS Our first thermal and energy model of the existing building conditions quickly confirmed that before we could consider any mechanical system options, we had to address the issue of the all-glass envelope. It had an enormous effect on the heating and cooling loads, especially in the summer when the solar gain would heat the space to uncomfortable conditions as soon as the sun hit it, in addition to the glass itself absorbing radiation, warming up and further radiating heat into the space. Conversely, but equally important, winter heat losses through the glass were also difficult to alleviate. Although briefly considered, the options of attaching external shading devices, adding an external double façade, applying a low-e coating to the existing glazing, or replacing it altogether with high-performance glazing were all out of the question due to the city’s requirements, capital costs, and delivery time. Another option that seemed more viable was to lower the temperature of the existing glazing via evaporative cooling, thereby alleviating the effect of the hot glass radiating heat into the space. We generated a model where water was sprayed on the outside of the glazing to cool it and the logistics were considered, but the method proved impractical and a waste of water. The most effective solution — and the one that best reduced the building loads — turned out to be the addition of a second façade, but there was a catch. Contrary to standard designs, the second façade would have to be added on the inside of the structure and would be an opaque wall made of a fabric similar to movie screens. The life within the building requirement from the city would be met with a low-energy, LED lighting scheme between the skins that would create the illusion of activity inside. Once we chose the envelope upgrade and determined the peak heating and cooling loads, our next challenge was to select an appropriate mechanical system. The inner building skin had removed the effects of the glass box envelope and the casino floor was now a cooling-dominant load. The existing building had several AHUs and high-level, four-pipe fancoil units, but these weren’t very practical for the intense cooling loads required by a casino or for such a high space. A more traditional approach for casinos is UFAD, as many casinos already use raised floors to conceal wiring to and from gambling equipment and lights. However, traditional UFAD was ruled out because of its reputation for creating uncomfortable areas of cold, fastmoving air drafts where occupants could be seated for long periods of time. A less-traditional system considered was the use of radiant panels to heat and cool the space, with a mixed-mode air system (natural and displacement ventilation) taking in outdoor air at low level and exhausting through the high atrium space. The radiant panels would be mounted on the underside of false ceilings in the main areas and in dropped ceilings over the card tables. Hot or cold water would circulate through small tubes embedded in the ceilings beneath a light drywall topping; the heat (or coolness when in cooling mode) would then radiate down to the occupants. Unfortunately, an adequate combination of surface area and cooling water temperature could not be reached; there either wasn’t enough ceiling surface area (especially in the Commercial Replacement Coils Tel: 800-225-4328 Fax 662-229-4212 OEM Coils Tel: 662-229-2000 Fax 662-229-2297 Aluminum Coils Tel: 662-229-2587 Fax 662-229-2571 ● ● ● ● ● ● ● Quality Lead-time Reliability Factory Trained Representation Selection/Rating Software ARI & UL Certification UL Qualified Client Test Data Program coils@luvata.com www.luvata.com/heatcraft Input 208 at www.esmagazine.com/instantproductinfo 26 En gi neer ed S y stem s August 2008 http://www.luvata.com/heatcraft http://www.luvata.com/heatcraft http://www.esmagazine.com/instantproductinfo

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Engineered Systems - August 2008 Contents Editor's Note Back2Basics HVAC Challenge Case In Point Commissioning Building Automation Efficiency Incentives HVACR Designer Tips Glass Box to Grand Casino Looking Radiant In Green Mechanical Products Sourcebook Q&A: Dehumidification In Schools Building Oversight Management: M&V And More Products Classifieds Advertiser Index Tomorrow's Environment

Engineered Systems - August 2008

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