WFTS Channel 28

Located adjacent to Tampa Stadium is the 73,000 square foot Scripps Howard Broadcasting television station, WFTS Channel 28. Designed to exhibit state of the art technology, it encompasses modern beauty and superior function.

The unifying architectural element to this building is the three-story skylight atrium along the building’s main axis which provides both a spatial and visual link between the three levels. This atrium is designed to display Master Control Room equipment areas, editing booths, and an immense news room so visitors can see production in the making, from commercials to newscasts. The north wall of the atrium is designed as back drop to display the station’s promotional material and products. Clients and visitors walk through this vast space, leading to a conference room by crossing a bridge which provides the most dramatic view down both directions of the main building axis. The conference room overlooks the 4,036 square foot, two story news room area and the three story atrium. Adjacent to the news room is a 3,472 square foot audience participation studio.

Continuing with the “cutting edge of technology” theme as predicated by the architect, several innovative HVAC technologies were used to achieve the goals of having an energy efficient system, maintaining indoor air quality, and ease of maintenance while minimizing first cost.

The central plant, located atop a five level parking garage adjacent to the studio, consists of two 135 ton air cooled reciprocating chillers, each fitted with a desuperheater. The desuperheaters recover waste heat from each chiller’s hot refrigerant circuit and reject that heat into water circulating through the desuperheater. This heated water is then stored in a 4,000 gallon thermal storage tank and is used as reheat water for maintaining temperature and more importantly, humidity control within the facility. A primary/secondary loop arrangement is designed for both hot water reheat and the chilled water systems. Chilled and reheat water is pumped to the studio via a packaged pumping system. The packaged pumping system was utilized to minimize construction and commissioning time and to have a pumping system that is optimized to have the best wire to water efficiency. The secondary loop pumps utilize variable frequency drives to supply only the amount of water needed by the systems.

The studios presented several design challenges. First and foremost was a noise level of NC 10. This was attained with the use of sound attenuators, double wall air handlers and ductwork with a film sandwiched between the insulation and the perforated inner wall, and by keeping the air velocities in the ductwork down to 500 FPM in the mains and 300 FPM in the branches. The film was used to keep the ductwork cleanable. The second challenge was addressing the drastic swing in heat loads. The studios remain dark and empty 90 percent of the time. Lights are energized and the crew is assembled about 30 minutes before a broadcast. The system had to be dynamic enough to react to 120 kw of instantaneous lighting load. The impact of people relative to the total load is small in the news studio. The constant air volume (CAV) air handler that serves the news studio mixes untempered outside air with return air, cools and then reheats it to maintain space relative humidity and temperature. On the other hand, the audience participation studio required preconditioning the outside air prior to mixing due to the high amount of moist Florida air (91&Mac176; DB/ 77&Mac176;F WB) required to meet ASHRAE 62-89. The outside air was preconditioned by use of an air handler with a precooling runaround water coil, a chilled water cooling coil, and a companion runaround reheat coil achieving eight degrees of precooling and reheat around the outside air cooling coil. This greatly reduced the latent load of the outside air prior to mixing with return air.

Production control areas, a computer room, and the archive tape room design used water cooled self contained computer room units for critical control of temperature and humidity.

The remainder of the facility utilized several chilled water variable air volume (VAV) systems, each with a dedicated outside air handler with a runaround water coil wrapped around a chilled water coil and a main air handler consisting of a cooling coil and a reheat coil along with a fan and inlet vanes. Noise levels were designed to be less than NC 35 in Executive offices, reception areas, general open offices, and corridors. externally wrapped single wall galvanized steel ductwork was used in these areas, again for IAQ cleanability. Space comfort is provided by VAV boxes with a thermostat strategically located in each respective zone. Each perimeter VAV box has an electric heater for space heating.

Quintessential to the successful integration of all the building components is a low cost, user friendly, energy management system for control of the HVAC system. The chillers and the packaged pumping system included open protocol. The building energy management system (EMS) has complete control over all aspects of the building HVAC system operation and monitors alarms from the computer room units.