The Nature Conservancy Headquarters

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Overview

• Location: Arlington, VA
• Building type(s): Commercial office
• New construction
• 172,000 sq. feet (16,000 sq. meters)
• Project scope: 8-story building
• Suburban setting
• Completed 1999

The Nature Conservancy's new headquarters is an eight-story 172,000 ft2 (16,000 m2) office building in the Ballston area of Arlington, Virginia. The Conservancy occupies six floors and leases two floors, which provide room for growth. Parking is accommodated in a garage below the building; the remainder of the site has been transformed into a 1/2-acre (0.2 ha) landscaped park.

Environmental Aspects

The Nature Conservancy wanted their new headquarters to reflect both their commitment to protecting the environment and their conservative use of donated funds.

As a private, nonprofit group that relies on donor support, the Conservancy is proud of the fact that most of its operating budget goes toward land conservation. Their goal for their new headquarters was to develop an environmentally responsible building design based on proven materials and technologies that would not increase the first cost of the building or compromise future re-marketability.

Owner & Occupancy

• Owned and occupied by The Nature Conservancy, Corporation, nonprofit

Keywords

Green framework, Transportation benefits, Brownfield redevelopment, Indigenous vegetation, Efficient fixtures and appliances, Drought-tolerant landscaping, Lighting control and daylight harvesting, Efficient lighting, Adaptable design, Benign materials, Recycled materials, Certified wood, C&D waste management, Occupant recycling, Daylighting, Moisture control, Low-emitting materials

Team & Process

Strategic Planning

Prior to selecting a site for their new facility, HOK worked with the Staubach Company to develop a strategic plan. The plan evaluated whether the Conservancy should renovate its existing headquarters, renovate a different building, or build a new facility. The economics associated with each scenario were considered together with an assessment of the environmental impacts and opportunities of each.

While their existing building had excellent Metro access, it had poor energy performance and a limited fresh air supply. Reuse of their existing 1960s-vintage building would have required extensive renovation. Architecturally, the building also posed limitations because of low floor-to-floor heights and small floorplates.

A criteria document was developed to communicate to prospective developers and building owners the level of design quality and environmental performance that the Conservancy wanted to achieve. Broad environmental performance goals were translated into building specifications to the greatest extent possible, so various site options could be reasonably compared. Topics included connections to public transit, daylight access, HVAC systems efficiency, water conservation, indoor air quality, green building materials, and infrastructure to support recycling.

LEED Green Building Rating System

The Leadership in Energy and Environmental Design (LEED) Green Building Rating System, developed by the U.S. Green Building Council, was used as a design guidance tool throughout the design process. The rating system was still under development at the time; however, the framework of issues had been established and released.

Green Cleaning Review

During site design development, specialists from Rochester Midland Corporation conducted a "green cleaning review" with members of the future building maintenance crew. The review generated a fairly long list of suggested revisions that would reduce maintenance requirements and limit environmental impacts.

• Lumen Micro was used for daylighting analysis.

• Energy modeling monitored the impacts of various options on overall energy performance.

[](learnmore.cfm?ProjectID=77) [Hellmuth, Obata + Kassabaum, Inc.](learnmore.cfm?ProjectID=77) Architect [http://www.hoksustainabledesign.com](http://www.hoksustainabledesign.com)

Finance & Cost

Cost data in U.S. dollars as of date of completion.

• Total project cost (land excluded): $16,250,000

The Conservancy's new headquarters was built within a standard speculative office building budget. No extra funds were allocated for green design. The cost of the building, exclusive of the parking garage, was about $64/ft2 ($690/m2). The cost of the interior fit-out for the Conservancy space was about $21/ft2 ($225/m2).

Typically, a build-to-suit headquarters project would have a slightly higher budget; however, the Conservancy was eager to keep its costs within market rates.

Construction Partner

To help control costs, the Conservancy entered into a negotiated contract with Foulger-Pratt Construction. The contractor, who was also serving as the developer for the site, participated as a member of the design team throughout the design process to provide cost estimating of design options.

Creative Trade-Offs

Because the Conservancy built their own building, they were able to make creative tradeoffs with their budgeted dollars. Instead of using expensive finishes in the entry lobby or a complex building form, for example, they were able to invest in an integrated daylighting solution that includes larger windows, perimeter light shelves, improved light fixtures, and daylight dimming controls.

Interior Design Pricing

The interior fit-out phase of the project used the more conventional design-bid-build delivery method. To help control costs, the team benchmarked potential fit-out costs using historical construction cost data, and also developed an interim pricing package during design development. The combined effort helped ensure that construction bids would conform to the budget once contract documents were complete, and that the project would be delivered on time.

Land Use & Community

The Nature Conservancy's new headquarters building occupies a full block in downtown Ballston. The principal exit of the Ballston Metro station is located on the southeastern corner of the site, with the Metro entrance and terminal diagonally across the street.

The building design is essentially a simple rectangle in plan, with a regular grid of deeply set windows in a precast concrete facade. The exceptions are the main conference room, which extends into the park on the north side of the building and the corner facing the Metro. On the corner facing the Metro, a three-story block marks the front entry, and the upper floors are pulled back 12 ft (3.7 m) from the street line.

Ballston is a rapidly growing inner-ring suburban community. Convenient Metro access, an evolving street life, and considerable mixed-use development are transforming this bedroom community into an urban locale.

Good Neighbor

The Conservancy's new headquarters building acts as a "good neighbor" to the community.

The brownfield site, once home to a gasoline station and most recently a surface parking lot, now contributes to Ballston's urban fabric.

The site plan placed the compact building along the street line, preserving a half-acre behind the facility for a neighborhood park, with ample seating for informal use and formal gatherings.

Reduced Parking Requirements

Though surface parking was permitted, the Conservancy built a below-ground parking structure. Because many employees take the subway or ride bicycles to work, the Conservancy's requests to decrease the size of the garage were approved by the county. Use of "buddy parking," in which cars are parked behind each other, also helped to reduce the size and cost of the garage.

The facility provides locked storage and shower areas for bicycle commuters and an on-site recharge station for electric vehicles.

• Property Evaluation

  • Assess property for integration with local community and regional transportation corridors

• Responsible Planning

  • Ensure that development fits within a responsible local and regional planning framework

• Properties with Excessive Impacts

  • Avoid contributing to sprawl

• Support for Appropriate Transportation

  • Provide showers and changing areas for bicycle and pedestrian commuters

  • Provide storage area for bicycles
  • Provide access to public transportation
  • Provide for electric vehicle charging

• Property Selection Opportunities

  • Look for opportunities for infill development
  • Select brownfield sites for development
  • Select already-developed sites for new development

Site Description

Native Plant Garden

The site plan includes a half-acre native plant garden behind the building. The garden courtyard will serve as a gathering place for employees and as an outdoor reception area for Conservancy events.

Planting areas were developed to illustrate the four stages of secondary succession in the coastal Piedmont region. Secondary succession is nature's process of reclaiming cleared areas. In the first stage a wildflower meadow is formed; seedlings of trees and shrubs emerge in the second stage. The third stage is marked by the gradual forming of layers of forest canopy. The fourth phase, which takes over two hundred years to establish, is a mature forest, which in this garden is symbolized by a mature oak tree. The large oak is especially appropriate in the garden because its leaf is the symbol used for the Nature Conservancy.

The garden presents a spectacular collection of native plants, both from the region and from parts of the United States with similar climates. Besides familiar natives such as black-eyed Susans, rhododendrons, azaleas, and native roses, the Conservancy chose rare and endangered species such as box huckleberry, buffalo clover, and barber's button.

One incredible survival story is "told" by the franklinia trees. Once native to the Altamaha River region in the southern Appalachians of Georgia, this species had not been seen in the wild since 1800; however, the species was revived by two botanists who propagated the tree from cuttings.

Because no irrigation system is required, use of native plants provides both beauty and economic benefits. The mix of wildflowers and grasses creates an alternative ground cover that is drought-tolerant and also limits the need for frequent mowing.

Proving that nature conservation can become part of the urban setting, this native plant park already has become an attraction for the entire community. Lured by its beauty and educational opportunities, the garden's visitors include everyone from schoolchildren to office workers, parents with strollers, hobby gardeners, and neighbors out for a walk.

Water

Office buildings in northern Virginia, where summer water shortages are common, typically have in-ground irrigation systems. Because native plantings were used on the site, no irrigation system was required. This reduced construction and operational costs while also conserving water.

All plumbing fixtures meet the water conservation requirements of the U.S. Energy Policy Act.

A central water purification system distributes purified water to the pantry sinks and coffeemakers. This low-cost feature reduces reliance on bottled water and its associated costs and wasteful packaging.

• Lot size: 1.60 acres
• Previously developed land, Brownfield site

Water Conservation and Use

Water Use

• Development Impacts

  • Limit parking area

• Ecosystem Restoration

  • Convert turf areas to native desert, prairie, or woodland ecosystem

  • Remove ecologically damaging non-native (invasive) species
  • Replant damaged sites with native vegetation

• Runoff Reduction

  • Avoid contiguous impermeable surfaces

• Water Conservation Education

  • Educate building management and employees about water conservation

• Remediation of Damaged Sites

  • Decontaminate brownfield sites

• Low-Water-Use Fixtures

  • Use low-flow toilets

• Site Planning

  • Site buildings so as to help occupants celebrate the natural beauty

Energy

Extensive energy modeling was done during design to seek out cost-effective, energy-efficient solutions. While significant savings were realized based on the use of daylighting and efficient electric lighting, the relatively small size of the building and modest energy requirements made it difficult to economically justify many energy-efficient upgrades to the HVAC equipment.

Daylighting

The architecture and interiors were developed to create bright, daylit office areas. Large floor-to-ceiling windows with high-performance glazing draw in daylight while minimizing heat gain. The deep precast concrete facade and light shelves on the south, east, and west facades provide sun shading to further reduce heat gain.

Architectural light shelves direct daylight onto the 9-foot-high (2.7 m) ceiling, which is finished with special high-reflectivity ceiling tiles to create a spacious, airy feeling.

Along the building perimeter, shades made of translucent cloth are mounted to the underside of the light shelf to control brightness. Above the light shelf, fixed louvers control glare from low-angle sun.

Inside the office floors, systems furniture partitions surround the open-office workstations to enhance privacy. The bright ceilings and views of buildings and sky above the light shelf are important for maintaining an open feeling on the floor, given that many of the partitions are 6 ft (1.8 m) high.

To optimize the selection of the window glazing, Lumen Micro was used for daylighting analysis, while energy modeling monitored the impacts of the options on overall energy performance. The glass above the light shelf is clear, with no low-e coating on the south, east, and west facades and a standard low-e coating on the north facade.

Electric Lighting

The office areas use high-efficiency, low-brightness lighting with automated daylight dimming and occupancy sensors to maximize energy efficiency while creating an exceptionally comfortable work environment.

The open-office lighting consists of 2x2-foot (0.6x0.6 m), 16-cell-deep louver fluorescent parabolic light fixtures that conceal T-5 compact fluorescent lamps. The lights are connected to a daylight dimming system that adjusts lighting levels based on changes in daylight availability. Lighting in the inner perimeter offices and support spaces is connected to occupancy sensors.

To differentiate the circulation space along the core from the opening office area, recessed 2x2-foot (0.6x0.6 m) uplighting fixtures provide brightness that compensates for diminished daylight levels.

Mechanical Systems

The mechanical systems developed for the building are fairly conventional for the building type, with a few noteworthy upgrades.

During operating hours, heating and cooling are controlled by VAV systems that maximize individual control. Small, modular chillers on each floor, which allow for one quarter of a floor to be operated at a time, provide a high degree of operational flexibility for after-hours operation.

During the heating season, building systems use an efficient gas-fired boiler for the morning warm-up cycle. The gas-fired boiler was a highly cost-effective upgrade for the building, accommodating almost all the heating load. Once the building has been started up in the morning, the heat generated by people and equipment is nearly enough to maintain temperatures throughout the rest of the day.

The concern for re-marketability made it difficult to realize savings from downsizing the HVAC systems. Because of the conventional expectations of the real estate market, the building was designed to 5 W/ft2 (54 W/m2) for lighting and plug loads even though the anticipated use is less than 2 W/ft2 (22 W/m2).

Options Considered

If the building used a central chilled water plant with the floor-by-floor VAV system, instead of the self-contained VAV system, the efficiency of the chillers would have increased from 0.80/ton to 0.65/ton or 0.58/ton. Even more important, the self-contained units lose efficiency at part load and the central chiller gains efficiency at part load.

Given the size of the building, however, the central chilled water plant, with its 30-year payback, could not be cost-justified. The options that combined the central chilled water plant with either ice storage or gas absorption units (which would receive a utility rebate) had more favorable but still inadequate payback periods of 11 and 10 years, respectively.

Operable windows were considered carefully but eventually not included in the design because of concerns about how to accommodate those who may not agree on whether windows should be open or closed.

Humidification

The ASHRAE 55 guideline for thermal comfort can be difficult to comply with in borderline climates like the mid-Atlantic, where humidity drops below recommended levels only a few days a year. While the Conservancy was concerned with providing a comfortable workspace for its employees, the cost of a full humidification system was prohibitive. As a compromise solution, central humidification is provided at the outside air intake rather than on each floor, a much lower-cost solution that was sufficient to produce comfortable humidity levels throughout the winter months.

• Light Sources

  • Use high-efficacy T-5 fluorescent lamps

• Heating Systems

  • Use high-efficiency, condensing oil or gas boilers and furnaces

• HVAC Controls and Zoning

  • Zone the building for modular HVAC control

Materials & Resources

The team specified building materials that limit environmental impacts, waste, and pollution throughout their life cycles. This included natural materials, local materials, and materials made from renewable resources and/or materials with recycled content.

Local Materials

The building lobby uses granite flooring from local quarries in Virginia.

Healthy Materials

All paints, stains, and adhesives have low VOC content. All solder for basic piping fittings is lead-free. The team specified low-VOC joint and seam sealers for all mechanical joints and seams, as well as low-VOC gypsum board joint compound.

Renewable Materials

Cork flooring is used in typical office floor elevator lobbies, and linoleum is used instead of sheet vinyl for pantry and copy room floors.

All wood material came from sustainably managed forests, as certified by a Forest Stewardship Council-accredited certification agency. The ash wood veneer doors use a "character-grade" wood, which makes use of wood that would otherwise be considered waste.

Recycled-Content Materials

Site furnishings are made entirely of recycled plastic. A formaldehyde-free, 100%-recycled cellulose fiberboard product serves as the backing for fabric panels in conference centers. Other materials with recycled content include ceiling tiles, insulation, steel, aluminum, and gypsum board.

Recycling

Each office floor contains a pantry and copy/fax/printer area with recycling and trash bins incorporated into the millwork base cabinets. The groundfloor loading dock accommodates the storage and staging of recyclables.

A chute system was considered for recyclables but was not included in the final design because it had a negligible effect on maintenance costs and no real effect on recycling rates. It was determined that recycling rates would depend on the provision of convenient collection areas and the commitment of the staff, not the method used to convey materials to the ground floor.

Construction Waste Recycling

Cost-effective recycling of construction waste was a priority for the Conservancy. Prior to the start of construction, the general contractor evaluated options to determine whether waste should be separated on-site or off-site. The decision was made to have waste materials separated off-site for recycling instead of separating on-site because of space limitations and the cost associated with using multiple containers.

• Formaldehyde-Free, High-Impact, Wood-Fiber Acoustical Wall and Ceiling Panels

• Job Site Recycling

  • Seek a waste hauler who can separate recyclables out of commingled waste

• Recycling by Occupants

  • Specify recycling receptacles that are accessible to the occupants

• Toxic Upstream or Downstream Burdens

  • Use true linoleum flooring
  • Use natural cork flooring

• Post-Consumer Recycled Materials

  • Use recycled-plastic benches or picnic tables
  • Prefer insulation with high recycled content

• Pre-Consumer Recycled Materials

  • Use gypsum board made with higher percentages of synthetic gypsum

  • Specify aluminum products made from high levels of recycled scrap

• Materials and Wildlife Habitat

  • Use wood products from independently certified, well-managed forests for finish carpentry

Indoor Environment

The interior office layout is more than 90% open plan, a strong departure from their old building's traditional planning, with closed offices along the building perimeter that isolated interior spaces from daylight and views. In this design, the closed offices were relocated to the building core and outfitted with full-length glass partitions, leaving the perimeter zone entirely open for daylight access and flexible planning.

The use of additional small conference rooms, shared teaming spaces, and "touchdown" stations for visitors and employees from field offices were features that helped make the open office planning work. The new offices also provide a ground-level conference center and lunchroom that offers direct access to the park for staff and visitors.

Indoor Air Quality

The building was designed to comply with ASHRAE 62, the industry standard for indoor air quality, and ASHRAE 55, the industry standard for thermal comfort.

Building materials were carefully selected to promote good indoor air quality. All interior materials—from the carpeting to the adhesives, paints, coatings, and sealant—have been screened to limit VOCs and other chemical content.

To reduce contamination during construction, the design team provided a suggested sequence of finish installation for the contractor. The sequencing is based on installation of wet materials that offgas as they cure prior to installation of dry, fleecy materials because the latter can adsorb contaminants and reemit them over time.

• Visual Comfort and The Building Envelope

  • Use large exterior windows and high ceilings to increase daylighting

• Visual Comfort and Interior Design

  • Design open floor plans to allow exterior daylight to penetrate to the interior

• Reduction of Indoor Pollutants

  • Use only very low or no-VOC paints
  • Use only very-low-VOC carpet adhesives

Awards

• Associated Builders and Contractors, Metropolitan Washington and Virginia Chapters Category/title: Interiors under $25/ft2 ($270/m2) Excellence in Construction Award

Learn More

Hellmuth, Obata + Kassabaum, Inc. Architect   [http://www.hoksustainabledesign.com](http://www.hoksustainabledesign.com)