The new headquarters for the National Wildlife Federation is a 95,000 ft2 (8,800 m2) office building located in Reston, Virginia, adjacent to the 475-acre (190 ha) Lake Fairfax Park.
The building houses office space as well as an education and training center dedicated to education outreach. The J. D. Hair Center, which is located on the ground level, receives visitors of all ages interested in learning about wildlife and conservation.
A communicating stair, open conference areas, a community lunchroom and fitness center, picnic areas, and trails through the site have all been developed to create a positive workplace environment that will enhance collaboration.
The National Wildlife Federation began its design process with an in-depth goal-setting session with the architectural firm William McDonough + Partners.
NWF made a commitment that its new headquarters building will demonstrate sensible stewardship of its financial resources through use of rigorous payback analysis to select "state-of-the-shelf" construction technologies and materials. The design team was charged to search for an optimal balance among the following competing objectives:
Building a unique, specific facility that is identifiable with NWF while maintaining the widest appeal in a future market for sale or lease;
Minimizing habitat loss and securing a place for wildlife on the site while occupying a large portion of the site for buildings, parking, and roads;
Creating a model of environmental sensitivity and providing an example for others to follow while exhibiting fiscal responsibility;
Creating a climate of collaboration while providing for individual privacy and solitude;
Providing amenities to enhance day-to-day life needs while reducing occupancy costs;
Respecting tradition while fostering experimentation.
Once complete, the team goals statement guided site selection and selection of the architect, and then provided guidance throughout the design process.
Energy modeling was first performed early in schematic design so the team could understand the impact of issues related to building orientation and massing. This early study allowed the team to construct a "base case" code-minimum energy model specific to the site and occupancy, and compare it to a series of "improved" design options. Parametric analysis was used to establish the range of improvement possible for each design strategy, to help the design team focus their effort. The team used energy modeling once again during design development to evaluate the cost and benefit associated with the various options. Detailed evaluations of the building design using alternative architectural and HVAC system solutions helped determine the most cost-effective solutions and quantified the relative environmental benefit of each.
NWF engaged its general contractor, the James G. Davis Construction Corp., for preconstruction planning so that cost could be evaluated throughout the process. The construction partner joined the team at the outset of design development and participated in all key meetings.
Cost modeling allowed the team to evaluate the cost associated with different materials, systems, and equipment as decisions were being made. To integrate life-cycle costs in the cost analysis, the economic benefit of energy savings from the various design options was built into the cost-modeling process.
NWF's site for their new headquarters building is a previously undeveloped land parcel in a conventional suburban office park. One of the reasons the team selected this site was its location next to a 130-acre (50 ha) conservation area within a 475-acre (190 ha) woodland county park.
While NWF initiated its move to a new facility in order to reduce operating costs, the new headquarters building was also seen as an opportunity to expand its educational outreach mission—in terms of both the work housed in the headquarters and the design. NWF embraced the tension between its ideals and its program funding objectives and described its vision for the building as one that would follow a "common sense and common ground" approach to conservation.
The goal for the new facility was to create an inspiring, healthy workplace with modern communication tools and daily contact with wildlife and their habitats in order to foster continuous learning and advance educational outreach. Additional goals identified by NWF included the desire to enhance quality of life and productivity; to encourage community, teamwork, and collegiality; and to reflect the history and culture of NWF.
Prior to the outset of design, NWF staff from several departments formed a site inventory team to prepare an inventory of the natural features and wildlife on the wooded site and adjacent land.
During design, the design team kept in regular contact with the site inventory team. As the site design progressed and plant selections were made, the design team could draw on the results of the site survey to select supplementary plantings that already exist on the site and those that would be complementary. As work progressed on the "backyard habitats," the team knew what wildlife was already resident on-site and so could design to accommodate it.
The site inventory had determined that much of the site vegetation was low quality because of the dominance of invasive exotic plants (e.g., wisteria); however, the northeastern corner contained a flourishing ecosystem with mature high-value vegetation that will be preserved to the greatest extent possible. A half-acre (0.2 ha) tree-save area in the property's northeast corner will prevent at least 30 mature trees—over 30-in. (760 mm) caliper—and associated understory vegetation from being removed.
The team carefully located the building to create the best orientation for daylighting and energy conservation while also fitting with the natural topography and preserving the most valuable trees. The building steps with the steeply sloping terrain, nestling into the topography to minimize the need for excavation and fill.
The market standard for parking calls for at least four spaces per 1,000 gross square feet (GSF) (90 m) of a building. After confirming that a future owner could add parking to meet that requirement, NWF opted to develop only 2.6 parking spaces per 1,000 GSF (90 m), the minimum required by the county. The reduction in parking greatly reduces the impervious surface area and protects open space.
Well known for its Backyard Wildlife Habitat program, NWF viewed this headquarters project as an excellent opportunity to showcase habitat demonstration areas. The team developed the site to accommodate a diverse range of meadow, woodland, and aquatic wildlife habitats. NWF's objective is for the entire site, even the building's patios and parking lots, to serve as demonstration wildlife habitats.
Landscape architects paid special attention to providing shelter, food, and water for wildlife in each habitat area. The landscape design includes fruit-bearing plants for food, and logs and brush piles for shelter, while the ponds provide water.
The dry pond area and open space in front of the building create meadow habitats, and the park edge on the site's north side is a forest habitat. An aquatic wildlife habitat is located at the building entry; visitors entering the building cross over this habitat on a bridge for a close look. The bioretention area is a habitat that will change over time through natural succession. It started as a meadow and, as the plantings mature, will develop into a forest habitat.
A variety of deciduous native vines that are popular with wildlife, such as Virginia creeper (Parthenocissus quinquefolia), Dutchman's pipe (Aristolochia macrophylla), and trumpet vine (Campsis radicans), climb the trellis structure, providing shade in the spring, summer, and fall. The trellis also promotes NWF's Backyard Wildlife Habitat program by providing a "vertical habitat."
The landscaping minimizes the need for irrigation by including only native species and emphasizing those that originally existed on the site. The only water used for irrigation is a drip irrigation system for the vines on the trellis.
The team selected grasses and ground covers that are about 24 in. high (600 mm) and will be mowed only twice per year. Because of safety concerns, an option has been developed that provides a limited mowing zone along walkways and parking lots.
To maximize daylight, the design orients the building with the long sides facing north and south. Building faces oriented toward the east and west, which experience difficult-to-control low-angle sunlight, are mostly opaque. The opaque west elevation effectively reduced peak loads that occur in the afternoon, after the building has experienced a full day of gradually rising temperatures.
The building features a "green trellis" that forms a screen wall 6 feet (1.8 m) in front of the south elevation. In summer, this green trellis reduces heat gain on the building's south side and filters the intense direct sunlight. In the winter, when the deciduous vines are dormant, the building benefits from heat gain. Energy modeling confirmed that this deciduous sunscreen is more effective at improving energy performance than more expensive design options that rely on fixed architectural sunscreens.
The indoor environment is enhanced by the presence of daylight, improved electric lighting, and measures taken to protect indoor air quality and acoustics.
Indoor Air Quality
Several enhancements improve indoor air quality compared to the typical speculative building model. Ventilation rates exceed ASHRAE Standard 62 for indoor air quality, air filtration makes use of 85% instead of 35% filters, and the VAV system uses a fan-powered system that improves air mixing and ventilation.
During construction, the building was continuously ventilated to minimize buildup of contaminants from wet building materials as they cure. The contaminants released during construction were limited, however, because water-based, low-VOC paints, adhesives, and finishes were used throughout.
Access to Daylight
The building massing has a large impact on the availability of daylight. Because of the relatively narrow building proportion, the majority of workspace areas are within 25 feet (8 m) of a window. The interior space planning supports the use of daylighting through the coordination of panel heights, location of "closed" support spaces in interior zones, and use of light-colored, light-reflective materials.
Stormwater runoff can pose water quality problems from the release of excess nutrients and sediment from landscaped areas, as well as hydrocarbons from roadways and parking areas. County regulations require that new development include measures to retain stormwater on-site and to improve water quality before it is released. Typical dry ponds often do not integrate well with natural environments because of steep grading necessary to fit them into the site and because plantings are not allowed in the embankment areas, which are actually designed to prevent infiltration. The bioretention area at NWF reduces the need for a larger stormwater retention area, or dry pond.
NWF chose to develop a natural stormwater management system that improves water quality, increases groundwater recharge, and nourishes adjacent Colvin Run, part of the Chesapeake Bay watershed. The natural system provides a diverse environment rich with habitat for wildlife.
Native trees, shrubs, and groundcovers that can handle the ebb and flow of water were used in combinations found naturally in the region, to create a living water filtration system. The low areas will be augmented with seasonal color such as yellow flag iris (Iris versicolor), spicebush (Lindera benzoin), river birch (Betula nigra), and button bush (Cephalanthus occidentalis). To address concerns about employee safety and visibility, taller shrubs will be concentrated at the bottom of the swales.
The parking areas will be lined with curbs with V-shaped cutouts, allowing runoff from the parking lot to flow into two large medians that have been designed as bioretention areas. Runoff from the building roof surfaces will be piped into the bioretention areas. Contaminants suspended in the runoff will be filtered naturally as the water percolates through the soil. In contrast to sand and gravel filtration systems, these living systems will not need periodic replacement.
A dry pond at the low end of the site is designed to control water quantities that exceed what the bioretention areas can manage; water will be retained in the pond and released slowly into a nearby stream. Water flows in the bioretention areas that cannot infiltrate fast enough will flow through underground pipes to the dry pond at the site's lower end. The dry pond will fluctuate with the seasons, retaining as much as 6 feet (2 m) of water during rainy periods and remaining dry at other times.
Water-conserving plumbing fixtures are used throughout. Lavatories use aerators and water-metering faucets, while water closets use manually operated flush valves.
Rainwater collected on rooftops and condensate from cooling are routed through the roof drains to the bioretention areas in the parking lots, thereby reducing the quantity of water requiring treatment.
Cost-effective upgrades to the building envelope include infiltration control and thermally broken frames for all windows. The team was surprised to find that improvements to the building insulative values could not be cost-justified. The expense of improving the building envelope from R-11 (RSI-1.9) to R-30 (RSI-5.3) had a 15-year payback. The team searched unsuccessfully for less expensive design strategies to increase the insulative value.
Efficient Cooling Systems
While the design uses a standard, low-cost, packaged VAV mechanical system, it incorporates some significant upgrades.
Improvements to the rooftop units include the use of a low-temperature air system that reduces energy usage for fans by providing smaller quantities of air for cooling at 50 degrees (10 C). An evaporative condenser was specified instead of the standard air-cooled condenser, boosting efficiency from 1.1 kW/ton to 0.85 kW/ton. The building also has high-efficiency pumps and motors and variable-frequency drives.
Strategies such as the enthalpy wheel for heat recovery—which might have been cost-effective in a building with higher energy requirements—could not be cost-justified for this building.
The most promising alternative system that was studied used hot water for radiant heat combined with a straight VAV system. Because hot air naturally flows upward and cool air naturally flows downward, fan-powered units would not be required. Unfortunately, because gas service was not readily available at the site, the first cost of the system was too high.
The lighting design achieves substantial upgrades in both quality and energy efficiency. Occupancy sensors are used throughout, and daylight switching is used in perimeter zones.
Lighting can be simply turned off during most daylight hours in the perimeter zones. While it involves a bit more participation from building occupants, separate switching circuits for the perimeter lighting zone are much less expensive than daylight dimming ballasts and sensors, and the energy savings can be even greater.
With the decision to increase ceiling height to just over 9 feet (2.7 m), indirect lighting became possible. Low-cost pendant direct/indirect fixtures were no more expensive than typical recessed fluorescent fixtures. Single-bulb "next-generation" T-5 fixtures mounted over the workstations provide an even distribution of ambient light, which is supplemented by task lighting.
NWF's new headquarters is a high-tech learning center that can link electronically to classrooms and conference centers worldwide. Online distance learning with live, nature-based lessons is available over the Internet and through videoconferencing.
Network and telecommunication connections for employees are wired throughout the building, as well as to outdoor patios and picnic areas.
Total energy consumption is evaluated on a regular basis. Monthly utility bills are compared and reviewed with respect to heating degree days (HDDs) and cooling degree days (CDDs), and evaluated on a cost-per-square foot basis. Any elevated readings are investigated for their source.
The building's Energy Management System and equipment are continually monitored and adjusted, based on occupancy status, interior temperatures / humidity and external weather conditions.
Nighttime energy audits are performed regularly to confirm off-hours operation (or non-operation) of building systems and other equipment (employee computers, task lights, etc.).
The team selected building materials that are environmentally preferable and practical. For NWF's headquarters, this means the materials are durable, low-maintenance, and low-cost. While many natural, renewable materials were considered for use, wood substitutes were selected in lieu of wood products wherever possible.
While some decks and stairs will be made with recycled plastic lumber, because it resists rotting, many of the materials used on the site will come from the site itself. The contractor stockpiled topsoil on-site for reuse, and land-clearing debris was shredded for reuse as mulch. Gypsum board scrap was ground for use as a soil amendment or sold to local landscaping contractors. Some of the plant material from the existing NWF headquarters site was moved to the new site by volunteers.
Exterior Building Materials
The building envelope includes split-face concrete block for large opaque areas and profiled metal panels for spandrel areas. The contractor sought out local sources of concrete block, and sources of metal panels and mullions with recycled content that use a powder-coated finish. Powder coating is a zero-waste, zero-pollution factory finish that is an environmentally friendly alternative to traditional high-performance finishes.
Interior Building Materials
The palette of interior materials is a simple one. Linoleum and carpeting are the primary flooring materials. Ceilings use a highly light-reflective tile with high recycled content. Walls are gypsum board and paint. Doors, millwork, and accent materials use natural, renewable biofiber materials that offer alternatives to the use of wood or synthetics.
Systems furniture was selected based on functional requirements as well as the manufacturers' initiatives to eliminate waste and pollution from the manufacturing process and to reduce chemical emissions from the furniture itself.
The design makes recycling easy and unobtrusive. Recycling containers were built into galleys, kitchenettes, and print rooms so that recyclables can be collected at the point of use. Space has been provided at the loading dock for a compactor and baler for paper and cardboard.
The building is a class B+ office building; the budget for the base building was originally set at $55/ft2 ($590/m2) with $20/ft2 ($215 m2) for interiors. To fund potential value-added upgrades, NWF set aside a contingency budget representing approximately 5% of the overall budget.
The conservative budget presented a challenge to the design team. Their task was to systematically challenge the typical low-cost development formula, providing a better building with lower environmental impacts. By staying within the budget, the team created a building to act as a credible model for others.
To protect its investment in the building, NWF feels strongly that the building must be able to be understood and valued by the local real estate market, in case the organization needs to vacate in the future. The concern for "exit strategy" influenced all design decisions and imposed an additional tension on the design process.
|Role on Team||First Name||Last Name||Company||Location|
|Contractor||James G. Davis Corporation|
|Construction advisor||Spaulding & Slye Colliers|
|Engineering principal in charge||Roger||Frechette||Vanderweil Engineers||Alexandria, VA|
|Electrical engineer||Tamara||Gray||Vanderweil Engineers||Alexandria, VA|
|Mechanical Engineer||Teresa||Rainey||Vanderweil Engineers||Alexandria, VA|