River of Life
These words are part of a presentation visitors hear upon touring the Sandstone Visitor Center, a launching point for travelers wishing to take in awe-inspiring, panoramic views of the tree-covered Appalachian Mountains, the New River Gorge Corridor and the New River itself in southern West Virginia.
These words are part of a presentation visitors hear upon touring the Sandstone Visitor Center, a launching point for travelers wishing to take in awe-inspiring, panoramic views of the tree-covered Appalachian Mountains, the New River Gorge Corridor and the New River itself in southern West Virginia. But these words and the spirit behind them significantly influenced the design of the center as well, as appropriate use and protection of water became a major design motif.
Contracting the experts
The New River, often claimed to be the second oldest river in the world, first attracted large numbers of people to its banks more than a hundred years ago. Beginning in the 1870s, with the coming of the railroad, migrants flocked to southern West Virginia in search of work, as coal mining and logging boomed in the region surrounding the gorge. One hundred years later, in 1978, the U.S. National Park Service (NPS) decided to preserve and protect 53 miles of the river, as well as 70,000 acres of land around its banks.
In the fall of 2003, the NPS crowned its creation—the New River Gorge National River unit—with the unveiling of the Sandstone Visitor Center, on Interstate 64 in Summers County, to serve as a gateway to the southern end of the river.
But the center is more than just an interpretative stop to introduce visitors to the area. Through team collaboration, and using principles of sustainability, the design team created a facility that in its very design demonstrates the NPS goals of preservation and conservation of the gorge and its stretch of the river.
The Sandstone Visitor Center consists of a 9,480-sq.-ft. space for exhibits and staff offices, a 1,470-sq.-ft. detached comfort station and a 1,350-sq.-ft. maintenance building. The site, buildings and educational exhibits all illustrate ways that people can practice an eco-friendly lifestyle, while also enhancing their knowledge of the park’s re-sources and heritage.
The combination of the environmental education mission and the rugged beauty of the site itself made natural preservation a theme of paramount importance, not only in the design and construction of this facility, but also in the creation of exhibits. In fact, when it came time to contract design firms for the initial design phase, NPS brought in not only architectural and engineering services, but also the exhibit designers, as well.
In a project such as this, it’s unusual to consider the exhibit component from the start. In this case, it worked to the advantage of NPS goals. The engineering team developed an energy model as a tool to evaluate building shape, orientation, fenestration and shading. And with the exhibit designers on the team, engineers were able to collaborate with them from the beginning to establish functional lighting energy goals and usage patterns.
A major driving force for the development of an energy model was the NPS Northeast Regional Office’s decision that the project be designed to meet the requirements of the U.S. Green Building Council’s LEED 2.0 platinum rating. This would prove to be a challenge, because at the time the project was started, the USGBC had yet to publish the 2.0 rating system. As a matter of fact, the designers were well into the design before the platinum accreditation exam was even offered.
Upon completion of the construction documents, the design included 54 LEED credits: 11 for sustainable site points; five water efficiency credits; 10 points each in the energy and atmosphere, and materials and resources categories; 13 indoor environmental quality credits; and five innovation and design process points. OK, you might ask, exactly how were these LEED credits achieved?
During several design charettes with the architect, Susan Maxman Partners, Philadelphia, engineers from H.F. Lenz developed a simplified building energy model using Energy 10 software to simulate the performance of the building’s thermal envelope, orientation and shading. This allowed the team to investigate environmental effects on the building’s energy performance and rank the design features. This tool was especially useful in evaluating the performance of the south-facing building, which was oriented so as to allow for maximum daylight and heating by the winter sun, while still providing visitors with views of the New River Gorge.
With the building’s physical features and orientation established, the engineers created a more detailed energy model to simulate the performance of the proposed HVAC, electrical and lighting systems. This was accomplished using Trane’s TRACE design tool. But first, the team also had to account for the fact that the project would be located in a remote part of the state where few public utilities are available. After studying several energy-efficient alternatives, a geothermal heat pump system with a dedicated ventilation air-handling unit and an energy-recovery enthalpy wheel became the logical choice.
A total of five horizontal-type air-to-water heat pumps, ranging from one to 3.5 tons in capacity, provide heating and cooling to the offices, bookstore and multipurpose room. Two nominal 10-ton water-to-water heat pumps seasonally produce hot or chilled water to serve the public spaces. Ventilation air from the energy-recovery unit is ducted to each heat pump where two position dampers regulate the flow of ventilation air to each space. Carbon-dioxide sensors located in each space compare space CO 2 levels against the outdoor ambient CO 2 level, and open or close the ventilation dampers to maintain a differential of 530 parts per million.
To maintain a high level of thermal comfort for both visitors and staff, an in-floor, hot-water radiant heating system was installed throughout the exhibit hall, bookstore, multipurpose room and in the restroom building. The “load” side of the water-to-water heat pumps is piped in a primary-secondary pumping arrangement. During the heating season, the heat pumps produce 120°F hot water. Two separate secondary pumping loops—one for heating and one for cooling—have also been installed. The heating loop serves the hot-water coil in the exhibit space’s air-handling unit, cabinet and horizontal unit heaters, fin tube and a tertiary loop for the radiant-floor heating. The tertiary loop provides hot water at a temperature of 100°F or lower, as required by the various spaces. The hot-water loop shuts off when the heat pumps switch over to cooling mode.
In cooling mode, the heat pumps produce 45°F chilled water. The cooling loop serves the exhibit AHU and operates only when the heat pumps are in cooling mode to prevent pumping chilled water into the radiant-floor system and supplemental radiant heating equipment.
A constant-volume, modular AHU provides ventilation, cooling and supplemental heating to the main exhibit space. Hot and chilled water from the water-to-water heat pumps serve the four-pipe unit. The equipment is able to maintain 50% relative humidity through the use of chilled water, in lieu of cycling compressors. The AHU is provided with minimum ventilation air from the energy-recovery unit. In addition to the minimum ventilation air damper, the unit is equipped with a full outdoor-air economizer. This allows the building to take advantage of free cooling with outdoor air and saves a substantial amount of energy over a typical heat-pump system.
As far as the geothermal side of operations, the heat-pump heat exchanger serving the system was intentionally overdesigned to limit the operating temperatures that the system is exposed to. The geo-exchanger consists of eight closed-loop vertical bores, each 450 ft. deep. The design produced a minimum temperature of 42°F and a maximum temperature of 76°F, allowing the heat pumps to operate at a very efficient level without supplemental heat.
Sending a green message
The Sandstone Visitor/Orientation Center officially opened in September 2003. While the building houses exhibits explaining the origin and history of the New River, “green” messages associated with sustainable design and the operation of the park are also located throughout the building. The exhibits show both the positive and negative impacts on the surrounding environment, and suggest ways for individuals to make a significant difference.
But it’s the building itself that delivers one of the strongest environmental and conservation messages. By assembling all of the components of the design team at the early phases of the project, clearly defining the design intentions and encouraging full communication and interaction between the design team members, NPS was able provide the New River Gorge National River with a visitor center that will use approximately 60% less energy than a facility that simply complies with ASHRAE Standard 90.1-1999. This is as important an environmental lesson as those taught by the center’s exhibits.
Location, Location, Location
Besides innovative HVAC systems, an important part of the project’s success was determining optimal building siting and investigating the site itself by testing water well capacity, soil permeability for ground water recharge systems and the potential for man-made wetlands.
Percolate testing revealed that high clay content of soil would negate the effectiveness of a groundwater recharge system. It was also determined that some type of retention system would be needed. To reduce the potable water required, as well as the wastewater generated, both gray water and collected storm water systems were employed.
In the early design development stage, the team discovered that reducing the water supply too dramatically could result in too little flow to adequately convey wastewater, dramatically increasing maintenance requirements. As a result, a wetlands wastewater treatment system was designed to treat gray water that would be used for water closets and urinal flushing. Reclaimed storm water, along with a small amount of black water, will also be utilized to improve the system efficiency.
One final note on symbiosis: Prior to the start of the design, the National Park Service made an agreement with a local municipality to be a part of a new sewage treatment plant that was under construction. In addition to treating gray water through the site’s constructed wetlands, most black water generated at the center will be transported to the municipal treatment plant, providing a solution that will be cost-effective over the life of the building.