Engineers and architects took the seemingly impossible task of recycling an outdated industrial factory into a LEED-Gold showcase of some of the HVAC industry’s most innovative equipment for Asheboro, N.C.-based Randolph Community College (RCC).
Transforming the former 46,000-square-foot, $850,000 Klaussner Furniture Plant’s un-insulated brick shell into a high-efficiency educational facility proved challenging for two Raleigh, N.C., firms, consulting engineering firm Progressive Design Collaborative (PDC) and architecture firm Smith Sinnett Architecture.
Thinking Outside the Box
Scott Ennis, project engineer at PDC, and Steve Campbell, president of PDC, thought well beyond convention with the encouragement of Cindi Goodwin, director of facilities at RCC. They designed one of the nation’s first combinations of active chilled beams with an off-peak-hours ice storage/chilled-water loop.
The foundation of RCC’s Continuing Education and Industrial Center’s (CEIC) cooling system consists of 184 IQHC active chilled beams and two Pinnacle® dedicated outdoor air systems (DOAS), both manufactured bySemco LLC. The chilled-water loop is supplied by a 130-ton Model CGAM air-cooled chiller with scroll technology manufactured by Trane and an ice storage system by Calmac. All mechanical systems were installed by American Industrial Contractors Inc., Greensboro, N.C.
The two-pipe chilled beams, which range from 2-10 feet in length, supply 100 percent of the $7.6 million facility’s cooling needs. Chilled beams have the potential for condensation in humid environments such as North Carolina, so PDC’s DOAS specification delivers dry outdoor air to the chilled beams to prevent condensation and comply with ASHRAE Standard 62. Besides providing a comfortable relative humidity (rh), the DOAS/chilled beam cooling system’s comparatively small 6-inch diameter duct-work saves significant ceiling space. Chilled beams have shown to use as much as 40 percent less fan horsepower than conventional rooftop and ductwork systems.
“We wanted to keep ceiling heights at 10 feet, so the inherent feature of the active chilled beams’ reduced duct sizes caught our interest,” said Ennis, who had never specified a chilled beam project before RCC, but who is already specifying another chilled beam project for a hospital with low ceilings.
Besides indoor air comfort, the two 10,000-cfm DOAS systems also add to the project’s sustainability and IAQ because they use molecular sieve enthalpy wheel technology to dehumidify outdoor air and recover heat from exhaust air for preheating outdoor air. The DOAS’ molecular sieve technology quickly adsorbs the exhaust air’s moisture, but not its contaminants that can potentially pollute incoming outdoor air and degenerate IAQ. The enthalpy wheel also uses acid-resistant, anti-microbial, and anti-stick coating treatments that help sustain the equipment’s lifecycle and maintain design static pressures.
Building Envelope Design
The building envelope was a LEED challenge for Robert Carmac, an architect with Smith Sinnett Architecture, Raleigh, N.C., because it lacked a vapor barrier, insulation, and other modern energy-efficient building materials. The original building’s wall and roof insulating values were low at R-3.45 and R-7.17, respectively. However, spray foam insulation was able to increase the wall and roof R values to R-14 and R-30, respectively, which are considerably higher than the minimum building code requirement of R-5.7 and R-15.
Based on the project’s energy efficiency, many of the CEIC’s HVAC technologies will be combined in future PDC projects, especially schools and hospitals, according to Ennis and Campbell.