Kentucky 's Mammoth Cave National Park ranks tenth in visitations amongst the U.S. National Parks. It has 2.1 million visitors each year, including 500,000 who tour the cave. Neither the current visitor center, which is more than 40 years old, nor the other public service facilities were designed to accommodate these large crowds. PB was hired to provide the design and construction supervision for a replacement structure that addressed current needs and provided a functional facility for the future. The park administration takes great pride in at Mammoth Cave having been designated as a World Heritage Site1, and being the core area of an International Biosphere Reserve2, a Green Energy Park3 and a national park. Thus, the decisions to implement sustainable design principles and to pursue Leadership in Energy and Environmental Design (LEED)4 certification were supported unanimously by all stakeholders. This project became PB's first design project to be registered with the U.S. Green Building Council for LEED certification consideration.
Current Conditions and Project Goals The existing facility comprises two buildings connected by an open breezeway. One serves the public by providing ticket distribution, restrooms, book sales and exhibit space; and the other houses the park administrative staff. The visitor center was designed to accommodate 1,500 people per day so is greatly undersized for the current peak visitation of 6,000+ people per day. It has no defined circulation pattern, and access to and egress from the ticketing area are through the same doors.
Tours are typically staged outside the ticketing area from where groups either walk or board busses to their tour start destination. Specific problems related to this arrangement are:
- Many visitors waiting to begin their tours stand in the breezeway because the plaza area around the buildings is small, making it difficult for incoming visitors to access the ticketing area.
- Both the walking and bus-boarding groups share the same space and become intermingled, making it difficult for tour guides to deliver instructions to their groups.
- The tour bus parking and loading area is located along the front edge of the visitor parking lot, so vehicular/pedestrian traffic conflicts occur when arriving and departing visitors must cross the path of the busses leaving for and returning from tours.
In addition, the park staff hoped to have a new facility with improved way-finding kiosks and signage for disseminating information to visitors as they approached the ticketing area; an adequate number of restrooms; and additional space for a future exhibit area.
LEED Considerations We determined that the basic level of LEED certification would be sought because additional credits would not serve the triple bottom line considerations as well. A charette was held for the design team early in the concept design phase, to assess the proposed facility against the five major LEED categories. This group then met often throughout the design phase to reassess the probability of meeting requirements for the selected credits in each category, which are:
- Sustainable sites
- Water efficiency
- Energy and atmosphere
- Materials and resources
- Indoor environmental quality.
The results of the LEED evaluation process and some of the reasoning that went into the decision to pursue or not pursue some of the credits are described below.
Sustainable Sites. We are pursuing six credits out of a possible 14 in this category:
- Site selection: The existing building footprint is being reused to eliminate disturbance to new land.
- Alternative transportation (2 credits): Bicycle racks, showering facilities and changing rooms are provided for employees. Also, the overall number of parking spaces is reduced by eliminating the parking lot for administrative staff.
- Reduced site disturbance: The park superintendent will designate an adjacent open area for non-development.
- Stormwater management: Pollutants will be removed from site stormwater runoff before it enters the cave ecosystem.
- Light pollution reduction: All site lighting will be low-level and aimed at the ground.
Several of the credits under this category were not applicable (urban redevelopment; brownfield redevelopment; and public transportation access) because of the building's location within a national park. Others were deemed unsuitable because of cost or detrimental site impacts. Stormwater management (rate and quantity) would normally be a goal, but it was not because water stored in detention basins could increase the volume of groundwater entering the cave below. Water Efficiency. Two credits out of a possible five are anticipated:
- Water efficient landscaping: Using native plant species in the landscaping eliminates the need for irrigation because these plants adapt to the climatic conditions of the region.
- Water use reduction: Twenty percent water reduction will be achieved by incorporating waterless urinals and motion sensing lavatory faucets outfitted with water economy aerators that limit the flow to 0.5 gallons per minute.
Treating wastewater on-site was not desirable for two reasons: the park is served by a recently constructed sanitary collection system, and there would be the potential for wastewater to seep from an on-site treatment facility into the cave ecosystems.
Energy and Atmosphere. Four credits out of a possible 17 are being sought:
- Reduction in energy usage (2 credits): Measures taken include building shell improvements (improved window, wall and roof insulation), reduced light density, lighting controls, energy-efficient heating-ventilation-air conditioning equipment, and an energy recovery ventilator (mechanical equipment that features a heat exchanger combined with a ventilation system for providing controlled ventilation into a building). The “base case” and “design energy cost” models were evaluated using the U.S. Department of Energy-2.1e building energy analysis computer program, and an annual savings of $6,015 was predicted.
- Ozone depletion reduction: elimination of hydrochlorofluorocarbons (HCFCs) and halon from air conditioning and fire suppression systems.
- Green power usage: purchase of renewable energy credits equal to the building energy use.
Other measures were not cost-effective enough to pursue, including additional building modifications, renewable energy equipment, and measurement and verification equipment.
Materials and Resources. Five credits out of a possible 13 are anticipated:
- Local/regional materials: Twenty percent is manufactured locally.
- Local/regional materials: Fifty percent of locally manufactured material is harvested locally.
- Twenty-five percent recycled content.
- Rapidly renewable materials: Five percent.
- Certified wood usage.
Indoor Environmental Quality. Eleven credits out of a possible 15 are anticipated:
- Construction indoor air quality (IAQ) management plan during construction and before occupancy (2 credits)
- Low-emitting materials, which included adhesives and sealants, paints, carpet, composite wood (4 credits)
- Indoor chemical and pollutant source control (separation of chemical use area ventilation and plumbing systems from regularly occupied area systems)
- Controllability of thermal, ventilation and lighting systems: perimeter and non-perimeter (2 credits)
- Day lighting: 75 percent of spaces
- Views: 90 percent of spaces.
Innovation and Design Process. Three credits are anticipated:
- Design innovation in educational displays, with information on the sustainable measures incorporated into the facility.
- Design innovation for the unique stormwater treatment system used to treat parking lot runoff and subsequently keep pollution out of the cave. We designed this system prior to the visitor center construction and provisions were included for handling the flows from the new visitor center. The treatment system combines a commonly used oil-grit separation unit that serves as a pretreatment to the filtration unit.
- Having a LEED-accredited person on our team.
Lessons Learned
LEED certification has become common practice in building construction, particularly for federal buildings with construction costs of $500,000+, where attempts at certification are mandated. In 2001 when we first scoped this project, however, the concept of LEED certification was not well-known. Even though we conducted significant research into the LEED process, we did not fully realize the documentation requirements until attending a LEED training workshop sponsored by the U.S. Green Building Council.
We learned that successfully completing the requirements for an approximately 50-page guide template required much more than time than the two weeks we had estimated. In fact, the workshop presenters suggested that the costs of implementing the LEED process would be in the range of $20,000 for an experienced team and up to $40,000 or more for a design team that had not been through the process previously.
The LEED certification process requires constant evaluation throughout the life of a project, from conceptual design through construction. As mentioned, the design team met several times to discuss the LEED considerations and the status of each potential credit. Similar meetings will be required during construction. Diligent monitoring will be required and considerable amounts of additional documentation will need to be prepared by the construction manager and the contractor.
Although the certification process itself requires considerable effort and cost, and designing and constructing LEED-certified facilities can be expensive, these higher initial costs should be offset by lower life-cycle costs and lessened environmental impacts. |
