Nation’s First LEED Platinum Pool Features HVAC Natatorium Design
Philadelphia’s Kappen Aquatic Center at the Overbrook School for the Blind (OSB) is the nation’s first U.S. Green Building Council LEED platinum natatorium. Ironically, however, the $11 million project for OSB’s 200 visually impaired and handicapped children wasn’t conceived as a LEED project.
Instead, OSB officials had simply requested a green, energy-efficient aquatic facility to replace the campus’ 102-year-old former pool building. Half-way through the project the design team realized their creative green strategy specifications were so effective that enough potential LEED credits had accumulated to qualify for the USGBC’s highest distinction of LEED platinum. “Our original goal was just a very efficient green building, so we were surprised to discover our final design strategies could accumulate 53 credits, which would qualify it as the first LEED platinum natatorium in the country,” said Amie Leighton, AIA, LEED AP, project manager, Daley + Jalboot Architects, Philadelphia.
Besides Daley + Jalboot Architects, other design team members included construction manager, W.S. Cumby, Springfield, Pa.; mechanical engineer, Vinokur-Pace Engineering Services (VPES), Willow Grove, Pa., and LEED consultant, Re:Vision Architecture, Philadelphia.
The energy-efficient design saves an estimated 43% of the 25,000-sq-ft facility’s energy costs compared to a conventional natatorium. The majority of the savings comes from off-peak energy loading, architectural building envelope features such as insulated concrete forms by Nudura Corp., Barrie, Ontario, and a HVAC dehumidification system by Dectron Internationale, Montreal, Quebec, that uses heat recovery from its dehumidification cycle to partially-heat/cool the space while also providing free pool water heating to the 75 x 50-foot competition pool and large therapy pool. Other factors racking up LEED credits were water efficient landscaping, low-flow water-saving fixtures by Sloan Fixtures, Franklin Park, Ill., recycled and local materials, low volatile organic compound (VOC) materials, 77% construction waste recycling, and other features.
The HVAC portion of the design includes energy recovery equipment and fabric ductwork installed by project mechanical contractor Tracey Mechanical, Newtown Square, Pa., and sheet metal contractor, Hays Sheet Metal Co., Pennsauken, N.J. The BAS controlling, which was installed by control contractor, Vortechs Automation, Huntingdon Valley, Pa., was also vital to the overall energy savings.
The DRY-O-TRON model DS-282 by Dectron dehumidifies the space to 50% relative humidity (RH) with its environmentally friendly R-134a dual refrigeration circuits, heats or cools the space, has built-in exhaust, two-inch insulated casing, and uses a hot gas heat recovery method to provide both free air and pool water heating prior to any heat rejection to the outdoor condenser. An estimated 100,000 gal of recovered condensate from the dehumidification process is sanitized and returned to the pool annually as a water conservation strategy. Manufacturer’s representative, Sass, Moore & Associates, Woodbury, N.J., was instrumental as a liaison between the VPES design team’s energy efficiency requests and the Dectron factory’s incorporation of them into the custom-manufactured dehumidifier.
One of several engineer requests was exhaust energy recovery using the dehumidifier’s glycol Smart Saver passive heat recovery system. The use of glycol as a thermal fluid allows the Smart Saver system to save substantial energy year-round by pre-cooling or pre-heating the outdoor air.
Likewise, the BAS is essential in the building’s energy efficiency. The two-block-long campus’ BAS by KMC Controls, New Paris, Ind., is combined with Genesis32 Automation Suite, a human machine interface (HMI) software by Iconics, Foxborough, Mass. The system inputs set point humidity and temperature to the dehumidifier’s on-board Supervisaire microprocessor that controls and monitors the natatorium’s environmental conditions. The BAS employs a demand control strategy to reduce energy costs, that’s incentivized with reduced energy rates by PECO, Philadelphia, a utility subsidiary of Exelon Corp., that serves 1.6 million electric and 486,000 natural gas customers in Southeastern Pennsylvania. “Because it’s a school with a residential component, all the buildings aren’t in full use at one time,” said Walter Horigan, president, Vortechs Automation. “Therefore we can limit equipment operation during unoccupied high-peak energy periods and then ramp up to optimum indoor conditions during off-peak hours.”
Many of the project’s contractors, including mechanical contractor Tracey Mechanical, helped contribute to LEED credits because of their Green Advantage certification, an environmental program that certifies contractors in green building techniques and materials. As a result, Tracey Mechanical used low volatile organic compound (VOC) solvents, glues for PVC piping, proper recycling techniques for job waste, and used mechanical equipment manufactured 500 or less miles in proximity to Philadelphia, according to Jim Kohler, Tracey’s Green Advantage certified project manager.
The locker rooms also received special energy-saving equipment. An enthalpy wheel-equipped energy recovery air handling unit controls the locker room environment. The 4,000-cfm unit has capabilities of pre-heating 11 to 58 F or pre-cooling 93 F dry bulb/75 F wet bulb to 81.7 F dry bulb/68.4 F wet bulb.
Other equipment includes nine 310-Mbh, 93% efficient boilers for domestic hot water from the Ultra Series 2 of Weil-McLain, Michigan City, Ind. All water circulating pumps are manufactured by Bell & Gossett, Morton Grove, Ill.
Because touch and hearing are important to the school’s vision-impaired students, the design team incorporated several non-energy related features. The dehumidifier, for example, was built with the two fan/motor/blower assemblies on springs to isolate any mechanical vibration from the building structure.
Likewise, mechanical noise is also an issue for blind students. VPES specified a low sound outdoor condenser to run at 560-rpm and a sound pressure rating of 62-dba at 10 feet from the unit, as compared to a conventional unit’s 1,140-rpm and 77-dba. “The condensers were built by Dectron to accommodate the lower rpm’s without affecting cooling capacity,” said Bill Moore, president, Sass, Moore & Associates.
The specification of fabric duct also complemented noise attenuation efforts. The softness of the fabric versus metal duct reduces mechanical equipment noise reverberation and fabric duct’s nozzle flow strategies tend to produce less airflow sound versus metal duct with registers, according to Leighton. The natatorium’s return grilles as well as registers and diffusers in other parts of the facility are manufactured with special corrosion-resistant metal by Titus, Richardson, Texas.
The architects also accommodated visually-impaired students with window and lighting placements that eliminated glare and direct, high contrasting light conditions. Utilizing tactile floor treatments that help students navigate away from pool edges or obstacles such as walls and handrails is a revolutionary approach for handicapped aquatics.
Tectum, Newark, Ohio, wall panels were also used to suppress noise throughout the facility.
The OBS is an example of a design team that set out to fulfill energy efficiency and green requests, but gave the client much more than it had asked for, LEED platinum.