The architectural combination of metal, glass and wood produces rave reviews at the new Esquimalt Recreation Centre indoor pool, but for the HVAC consulting engineer, Jimmy Ng, these condensation-generating materials presented a dehumidification and air-flow challenge.
Unless the air-flow design had enough throw and consistency, the high humidity loads could have long-term effects on the striking interior design of project architect Cannon Design in Victoria, British Columbia. Condensation possibly could cloud the hundreds of square feet of window surfaces while deteriorating the metal and wood structure in the long run.
Besides the material concern, Ng, a project engineer at Stantec Consulting Ltd. in Vancouver, also faced a myriad of moisture-generating pools at different temperatures including a 78-foot-by-42-foot lane pool at 85ºF, a 16-foot-by-16-foot children's pool at 90ºF, a 14-foot-diameter spa at 105ºF and a 40-foot-by-60-foot leisure pool at 90ºF. The natatorium, which is part of an $8.1 million renovation and addition to the existing 30-year-old recreation building, also includes moisture-generating toys such as fountains and water canons that add to the large humidity load.
Combining those moisture-elimination challenges with Recreation Centre Operations Manager Yves Bienvenu's request for value engineering, Ng realized the 12,000-square-foot natatorium's HVAC design would test his design team's expertise. While the majority of the center's other HVAC engineering duties were handled by another firm, Stantec was chosen for the natatorium portion of the project because of its prior indoor pool work.
"This was probably the most difficult indoor pool project we've ever designed," Ng says.
Part of Stantec's value engineering included eliminating under-deck ductwork, which commonly is used to keep the bottom of windows and walls free of condensation. Instead, his strategy of maintaining a 55 percent relative humidity throughout the space relied on Victoria's moderate climate and using only overhead ductwork, which saved 15 percent in total HVAC costs.
"Under-deck ductwork is certainly nice to have and mandatory in a cold climate, but I didn't think we needed it if our overhead system was designed correctly," Ng says.
Saving another 20 percent in ductwork materials and installation labor was the specification of white fabric duct from DuctSox instead of traditional spiral metal duct. DuctSox's Sedona model was less expensive than metal duct, which needs protective epoxy paint coatings in the corrosive environment of humidity and pool chemicals.
Aesthetically, the clean lines of the fabric duct replace the ribbed look of metal and add to the futuristic architecture of the facility.
Although he knew it would save money, Ng was concerned with the air-delivery performance of fabric due to his lack of exposure to the product. However, Gerry Lentz, a sales engineer, worked with Ng to have DuctSox factory-engineer each duct section with the necessary Sonic Vent perforation sizes and placement to assure proper air throw and consistency.