The National Wildlife Federation strives to inspire communities nationwide to protect and conserve wildlife and other natural resources in ways that will sustain the environment for the future. To advance this mission, NWF selected the Washington, D.C. office of Hellmuth, Obata + Kassabaum (HOK) to design a new 100,000-square-foot headquarters in Reston, Virginia. A primary reason for planning the new facility was to reduce operating costs so that more resources could be directed towards conservation work. It was also an opportunity to promote their educational outreach mission, both in terms of work within the building, as well as through the design of the building and site itself.

 

Located a short distance from the existing facility in suburban Virginia, the new building is adjacent to a 130-acre conservation area within a 475-acre Lake Fairfax Park. Design and site development were key components of the project to promote complementary activities, and physical and visual access to the park.

 

Economics

 

The new Class B+ facility was budgeted at $55-square-foot for the base building and $20-square-foot for interiors, which represents the low end of the spectrum for speculative real estate development. A contingency budget representing approximately 6% of the budget was set aside to fund potential upgrades to the building that would add value to the project, and were considered on a case-by-case basis.

 

Speculative buildings at that cost typically follow prescribed formulas that lead to predictable results. “The challenge here was an interesting one because NWF had several agendas going at the same time,” says HOK Senior Principal Bill Hellmuth, AIA. “One was clearly the sustainable agenda; however, equally clear was that they wanted the project to come in at $55-square-foot, first cost. Most buildings of this sort are usually $65-square-foot or more.”

 

The design team systematically challenged the development formula resulting in a better building with lower environmental impacts. By staying within the budget, the team has created a building that represents a credible alternative model for others.

 

In addition to the near term economic planning for the facility, concerns about "exit strategy" and "re-marketability" had a large impact on decision-making. NWF felt strongly about protecting its investment by ensuring that the building would be understood and valued by the local market if and when NWF ever needs to sell. “I don’t believe they imagined a building with trellises, profile panels, or split face block,” Hellmuth says. “But we stretched the limits in terms of appropriate materials, primarily because of budget considerations. If they had had a larger budget, we might have been more conventional.”

 

Design Process

 

NWF began the design process with an in depth goal setting session, working with the architectural firm of William McDonough + Partners. Through that process, NWF developed a model that reflects its "common sense and common ground" approach to conservation that includes environmentally sensitive design and construction of buildings, their sites, and the larger landscape.

 

The HOK team continually evaluated the design to examine issues of cost effectiveness and environmental sensitivity. A “green” outline specification was developed to benchmark the building’s design relative to site design, energy efficiency, water conservation, indoor air quality, daylight access, green building materials, waste management, recycling, and interface with public transit. These alternatives were incorporated within the constraints of the construction budget.

 

Because this was a design/build project, the team had the opportunity to constantly evaluate costs. Energy and cost modeling processes were closely integrated to develop the energy benefits, life cycle, and material selection cost analyses and impacts associated with various design options.

 

Site Design

 

Prior to the beginning of design, a site inventory of the natural features and wildlife on the wooded site and the adjacent lands was prepared by the NWF staff. The HOK design team maintained regular contact with NWF's Habitat Team, made up of employees from a range of departments.

 

The building steps with the steeply sloping terrain, and is nestled into the natural topography to minimize disturbance and keep the need for excavation and fill to a minimum. Native plantings support local wildlife and reduce the need for irrigation and frequent mowing.

 

Energy

 

Energy modeling was performed with DOE-2, a program that allows for more accurate simulation of architectural design strategies. First performed early in schematic design so that the impact of issues related to building orientation and massing could be understood, it allowed the comparison to an "improved" design to determine an estimate of energy savings potential. Detailed evaluations of the building design were developed with alternative architectural and HVAC system solutions to help the team determine the solutions that were best for the environment and most cost effective.

 

The building is narrower than typical office buildings, the long north facade that overlooks the park is a curtain wall of glass that not only offers beautiful vistas, but also floods the interior spaces with natural light to create a welcoming atmosphere. The east and west facades, that would be subjected to difficult-to-control low-angle sunlight, are almost completely opaque.

 

Upgrades to the building envelope also proved to be cost-effective. Improvements to glazing performance, the insulative value of the roof and walls, and infiltration control cannot be taken for granted in a low budget building, but energy modeling confirmed their value.

 

A "green trellis" forms a screen wall six feet in front of the south facade.  Deciduous native vines provide shade, reduce heat gain, and filter the intense direct summer sunlight. In the winter, when the vines are dormant, the building benefits from solar heat gain. Energy modeling confirmed that the deciduous sunscreen was more effective at improving overall energy performance than more expensive design options that used fixed architectural sunscreens. The trellis also ties into the Backyard Wildlife Habitatä demonstration gardens by providing a "vertical habitat.”

 

Water use for irrigation is extremely limited; a drip irrigation system is provided for the vines on the green trellis – no other irrigation is required. Bio-swales and man-made wetlands cleanse runoff from internal roadways and parking areas.

 

Rule of thumb engineering for this building type dictates a 330-ton cooling plant, but detailed energy modeling and a careful analysis of the design criteria led to an 80-ton reduction in the size of the cooling plant. The reduction could have been greater, but the benefit of reducing first cost was weighed against the concern of re-marketability. The same concern lead to the decision to compromise with electrical energy: NWF peak usage is only 1 watt-per-square-foot, but the installed system supports a more standard 2 watts-per-square-foot.

 

The nine-foot ceiling height made indirect lighting possible, allowing substantial upgrades in both quality and energy efficiency. Pendant direct/indirect fixtures, believed by many to be a high cost solution, proved to be no more expensive than typical recessed fluorescent fixtures. Single bulb "next generation" T-5 fixtures mounted over the workstations create an even distribution of ambient light, which is supplemented by task lighting. Occupancy sensors are used throughout along with daylight dimming in perimeter zones.

 

Materials

 

Building materials selected are environmentally preferable and practical, which in this case means durable, low maintenance, and low cost. The building envelope is split face concrete block for the large opaque areas, and profiled metal panels for the spandrel areas. The concrete block is locally manufactured, and the metal panels have a high amount of recycled content and a powder-coated finish.

 

The palette of interior materials is a simple one. Sealed concrete, local stone, linoleum, and carpeting are used for primary flooring. Acoustic ceiling tile and gypsum board have high-recycled content. Natural, renewable materials are used as accents, such as compressed straw doors, cork flooring, and bio-composite materials for built-in millwork. Recycling procedures in galleys, kitchenettes, and print rooms are easy and unobtrusive.

 

The overall design process was one of partnering – HOK met extensively with various NWF constituents, staff, board members, and volunteers, collaborating to ensure that all needs were met in a facility that satisfies the spatial needs of the organization’s 300 employees, while reflecting the Federation’s overall commitment to the environment.

 

The final design demonstrates a positive relationship between new construction and the surrounding ecosystems. The project received an Award of Merit in 2001 for Best Build-to-Suit Under 150,000 SF from the National Association of Industrial and Office Properties (NAIOP).

 

HOK Team

Base Building: Bill Hellmuth, AIA, Dunkan Kirk, RA (Principals), Sandy Mendler, AIA (Director of Sustainable Design), Amy Coe, John Folan, AIA, Tatiana Haagensen (Senior Associates), Manuel Sanchez, Ruth Kockler (Associates), Hyun Kim

Interiors: John Varholak (Senior Associate), Steve Woodyatt, Anne Mazzola

 

Project Consultant: William McDonough + Partners, Charlottesville, VA

Structural Engineer: American Structural Engineers, Falls Church, VA

M/E/P Engineers: R.G. Vanderweil Engineers, Alexandria, VA

Suppliers: Greenscreen (green trellis); Betco (split face block); Centria (profile metal panel); Teknion (systems furniture); Martin Brattrud, Sandy Seating (seating); Metalumin, Lightolier (lighting); Armstrong (ceiling tile); Interface (carpet); Bamboo Flooring International Corp. (wood flooring); Armstrong Flooring (vinyl composition tile); Benjamin Moore (paint)

 

Photography: Michael Houlahan/Hedrich Blessing 312-321-1151

 

Hellmuth, Obata + Kassabaum, Inc. is a full-service A/E firm with more than 40 years of architectural design experience, and a staff of approximately 2,000 professionals. HOK was ranked by Building, Design & Construction’s 1999 survey as the number one architectural/engineering firm; Engineering News Record’s 2000 survey of top U.S. design firms named it as the top A/E firm in general building; and, in 1999, World Architecture ranked HOK as the largest A/E firm in the world. The Washington office opened in 1968 with the commission for the National Air and Space Museum.