With the tremendous heat load produced by mission-critical broadcast operations servers and associated high-tech equipment at the corporate headquarters of Scripps Networks (Knoxville, TN) mechanical engineer Greg Farmer needed a reliable means to cool and dehumidify the space.

Maintaining precise 24-hour space conditions with back-up redundancy from the cooling system is critical for the newest broadcast operations floor of Scripps, which is the home of HGTV and other networks.

HVAC failure is not an option for Scripps' new computer and digital broadcast environments, which are part of Scripps' 36,000-sq-ft addition. Failure to maintain a precise temperature in this area of Scripps' new addition could cost hundreds of thousands of dollars in lost broadcast revenue, not to mention equipment replacement. This redundancy is achieved by designing a mechanical cooling/dehumidifying system to automatically switch from rejecting heat to the heat pump loop or an outdoor condenser.

Farmer, a vice president of mechanical engineering at A/E firm Michael Brady Inc., provided Scripps significant cost savings by using 14 Dry-O- Tron(r) dehumidifiers by Dectron Internationale to control the conditions in the technology area.

"With Dectron, I saw an opportunity to design something that offered redundant back up within the same unit," explained Farmer. "This allowed me to take advantage of the water source heat pump loop and reduce equipment costs. I'm still providing the required redundant backup required by the owner, and this might change how future computer and server rooms are built and air conditioned."

Cost savings

The use of packaged dehumidifiers consumes the same 4,000-sq-ft floor space of the corresponding technical room equipment, but since there is no associated central plant and accompanying mechanical space, approximately 1,000 sq ft is saved. With construction costs averaging $125/sq ft, this amounts to a savings of $125,000.

Furthermore, building operational costs are saved because the technical room requires year-round cooling. During the heating season the dehumidifiers automatically reject heat into the heat pump loop. The resulting increased loop temperatures improve the effectiveness of all the other heat pumps connected to it. This feature provides heat for the addition's offices and other areas at an annual energy savings of $5,000.

Space was also saved on the roof. Installing one condenser for each of the 16 dehumidifiers would have required thousands of sq ft because of clearance required between neighboring condensers, not to mention the visual impact. However, Farmer specified only four custom-manufactured condensers with multiple circuits by Dectron's heat transfer division, Ref-Plus.

Farmer's HVAC design also saved on capital costs of purchasing a new backup boiler for heating. Because the Dry-O-Tron units' continual cooling modes supply steady heat to the water source heat loop, any backup heating will be handled by a rarely used, existing, on-site boiler.

"My calculations reveal that the boiler probably will never be needed," said Farmer. "Even on the coldest of days, the contribution of heat from the Dry-O- Tron units allows the heat pumps to handle the entire load."

Farmer also figures that maintaining packaged dehumidifiers versus chillers will save an estimated $10,000 to $15,000 in annual maintenance costs. Scripps' in-house staff, which is already trained in DX equipment, can perform most service tasks.

The HVAC layout

Farmer's design, which was implemented in coordination with Michael Brady architects, called for a 265-sq-ft mechanical space that's inside the technology room, but walled off from the five, 22-ft-long, 8-ft-high racks of computer equipment they cool. Nested in between the racks is the mechanical space, which has three Dectron DA5-30 dehumidifiers as well as prepiping for future expansion. Two units are for current conditions and the third serves as a redundant back up. The mechanical space also includes two DA5-10 dehumidifiers (again with pre-piping for future expansion) that serve the adjacent broadcast control center and its equipment.

Above the first floor mechanical room is a 592-sq-ft secondary mechanical room that houses six more DA5-30's for the main technical room. Additionally, a hot backup site of corporate IS/IT servers includes three more DA5-30 dehumidifiers and piping accommodations for expansion.

Farmer believes more future technology applications will require smaller spaces that are part of corporate headquarters and offices. The trend will be 500 to 1,000-sq-ft computer or server rooms.

"Corporate CEO's are beginning to realize that the heat generated by these small rooms combined with water source heat pumps are capable of heating part or all of the building," said Farmer.

Reopened in 2000 after a $20 million restoration project, the Westin Poinsett Hotel (Greenville, SC) combines 21st century comfort and technology with the grace and charm of its 1920s design. Original architectural features have been preserved, while new MEP systems have been installed in the hotel's public areas and 200 guestrooms on 12 floors. It's a seamless match up that required technical expertise and creativity.