- Rooftop solar panels provide additional warmth to the waters.
- Maintenance workers closely watch energy usage remotely via a software program that lets them adjust settings and spot red flags for immediate repairs.
Goals and challenges
Guests at this 52,000-square-foot facility are positively swimming in efficiency. The Buffaloe Road Aquatic Center harvests solar rays and castoff heat from an HVAC system to warm the waters. Artificial light is minimized; stormwater is curbed through a vegetated roof and water is wisely conserved through an advanced filtration system.
A product of the city of Raleigh’s emphasis on reducing its carbon footprint, BRAC opened in 2012 with the goal of providing a recreational amenity in an underserved community. Given its eco-credentials, it’s a candidate for LEED certification.
How they did it
Dehumidification: Not even hot air goes to waste. The natatorium is conditioned using a specialized HVAC unit that maintains indoor air temperature and humidity, which throws off a considerable amount of excess heat. That heat is captured in a recovery wheel and routed via hot water piping to an exchanger, helping maintain a comfortable pool temperature.
However, there are days (typically during the winter) when the pool will require more heat than the HVAC unit can produce. Under these circumstances, the water heating will be supplemented by either the high-efficiency gas-fired boilers or by the solar panels, or both. All these heat sources are merged into a single heat exchanger and then drawn upon as needed, either for pool heating or HVAC reheat.
Solar panels: The solar heating system was funded with government stimulus money and provides supplemental hot water that can be used for a variety of purposes. If the dehumidification system is providing adequate heat for the pool, the heat drawn from the solar panels will be mostly directed to showers and sinks.
The hope is for the facility to run three-quarters of the year on nothing but solar and heat recovered from the HVAC system and only turn on the boilers when absolutely necessary.
Smarter lights: A series of monitors measures the amount of daylight entering the natatorium, then adjusts the level of artificial light required to meet minimum foot-candle requirements.
Motion-activated lighting: For all occupied spaces except the natatorium, lights are activated by motion detectors. If a space is unoccupied, the lights will be automatically turned off after about 30 seconds.
Lamping: The project uses no incandescent lighting. All lamps are high-efficiency metal halide (natatorium globe pendants), high-efficiency fluorescent (compact and T-8 tubes) or LED.
LED site lighting: Site pole lighting is installed with highly efficient LED lamps. Moreover, each fixture has an internal motion detector that will elevate light levels whenever it detects movement — either vehicular or pedestrian — in its vicinity.
Regenerative media filter: This technology uses perlite to provide pool water filtration equal to and above health department standards, but does so with less backwashing than sand or DE filtration systems. Facility managers estimate that it uses about one-tenth of the water, resulting in appreciable savings throughout the year.
Smarter landscaping: A basketball court-sized roof of vegetated matter filters stormwater through beds of soil. The water is then directed to a rain garden for further filtration, slowing its reintroduction into the water table. As an added bonus, the roof’s greenery boosts its insulation value.
Plant species: Most plants are native to this corner of North Carolina and are either drought-resistant or drought-tolerant.
Glazing: All glazing is double-glazed, low-e glass (meaning the air space between the two panes of glass is evacuated and filled with an inert gas — xenon — which prohibits heat transfer between the exterior and interior face of the window). The window and curtain-wall frames also are designed to limit heat transfer.
Insulation: The walls and roof of the building have enhanced insulative values. Walls are rated at R-22 and the roof assembly is R-40. (That doesn’t include the added insulation provided by the roof’s vegetation, which is estimated to kick up the R-value by 2 to 5.)
Construction waste management: The contractor estimates that 85 percent of the building waste was recycled.
Low VOV materials and finishes: The specification gives priority to materials and finishes that have low off-gassing properties, improving indoor air quality.
The city of Raleigh has been ramping up its conservation efforts in recent years, committing to overhauling all municipal buildings with green technology. With each upgrade, the buildings are brought online, allowing the city’s maintenance department to monitor a building’s energy performance remotely though a comprehensive management system.
This way, the staff can understand the building’s schedule, turn down the heat when it’s not occupied, and adjust it to accommodate holidays. In addition, they can now generate a history of building performance that allows them to easily make alterations where needed.
In the case of BRAC, every pump, valve, fan and light switch is wired to the system and there’s someone at the maintenance facility watching it every day, making sure it’s operating at peak efficiency.