Energy Harvest

By Craig DiLouie

The location for the National Association of Realtors’ (NAR) new headquarters in Washington, D.C., was ideal - just three blocks from the U.S. Capitol, highly visible at the intersection of New Jersey Avenue and First Street - but the property on which it would be built was a narrow, derelict brownfield site with a triangular shape.

NAR wanted an object building that would make a strong visual impact on the area while minimizing its environmental footprint. Cambridge, MA-based architects GUND Partnership achieved this vision with a striking landmark building that became Washington, D.C.’s first to achieve LEED-NC Silver certification.

“The client saw the site as an opportunity to reclaim the urban plane of the street, while creating a new icon that would be seen not just as a sustainable workplace, but also as a signature address for tenants,” says Graham Gund, FAIA, president of GUND Partnership.

The 100,000-square-foot building has been recognized with the 2005 American Architecture Award (Chicago Museum of Architecture and Design), the 2005 Sustainable Design Award - Design Excellence Citation (Boston Society of Architects Committee on the Environment, New York City American Institute of Architects Committee on the Environment in Architecture), and the 2005 Award for Architecture (Boston Society of Architects). From its bold architectural statement to the breadth of its sustainable design features, the new NAR headquarters appears to have been built without compromise.

A Fluid Building Expression
Graham Gund envisioned the NAR headquarters, with its combination of transparent and opaque elements in the building skin suggesting abstract sculpture on a grand scale, as a glimmering beacon in the Capitol district. The new building stands out from the tightly controlled urban landscape through its four-sided wedge-shaped site, its curved forms, and vertical marker, while suggesting homage to area monuments. A pair of tautly curved glass panes floats about an inner structure revealed through material transparency.

“The resulting sculptural form is anchored by a rising vertical framework marking the important convergence of two streets,” he says. “Dynamic juxtaposition of form and material create a fluid building expression that changes from different vantage points throughout the city, creating a distinct and unique identity for the NAR. The transparent elements cast an ethereal glow and speak to NAR’s role as an information clearinghouse.”

NAR occupies five floors of the new building, with its 100 employees enjoying views of the Capitol from the upper floors and roof deck and east-west views slicing across the north-south street. The other seven floors of the building will be leased to tenants, including retail at the ground level.

GUND Partnership’s Laura Sanden-Cabo, AIA, principal-in-charge of the NAR project, says that the building benefited from a modern interpretation of the zoning regulation for bay windows that allows a 4-foot projection beyond the building envelope. “By treating the entire façade as a projecting bay, the floor plates became more viable for commercial development,” she adds. “The building tapers from 60 feet wide on the south to about 10 feet on the north. These dimensions accentuate the building’s 130-foot height.”

Sustainable Savings
In addition to architectural solutions, the NAR headquarters also includes a range of sustainable design features that enabled the building to achieve LEED-NC Silver certification. “The client wanted a green building in an effort to make a statement that realtors do care about the environment,” says Gund, adding that NAR also regarded lower utility bills as a means of attracting additional tenants.

Sustainable features include efficient use of water and energy and other features that reduce energy use by 39 percent from the base case, the reference building created within the energy modeling. These features minimized the building’s carbon emissions, which were further reduced by 50 percent for the first 2 years by buying renewable energy from sources meeting Center for Resource-e requirements. The resulting premium was $2 million added to the total $44 million construction cost, including the building and NAR fit-out of five floors. NAR treated this as an investment to be recovered through utility cost savings and greater attractiveness to tenants.

More than 50 percent of materials, such as carpet tiles and acoustic tiles, feature recycled content and were manufactured and/or purchased within 500 miles from the site, minimizing the pollutant by-products of transportation. Low-emitting paints and carpets, coupled with no volatile organic compounds in the construction materials, significantly reduce interior pollutants. Light-colored concrete pavers on the roof deck reduce both heat gain and the cooling load.

Vegetation, including trees on the grounds and a trellis on the roof terrace with drought-resistant plants, is also used to reduce the heat island effect and reduce cooling requirements.

Sensible Lighting
More than 90 percent of habitable spaces have access to daylight and outside views, providing both an amenity for employees/tenants and a source of energy savings. Daylight is converted to energy savings using daylight-harvesting photosensor controls, which keep the lights off when sufficient daylight is available. Occupancy sensors automatically shut off lighting in spaces that are unoccupied. Additional automatic shutoff is provided by time clocks, which switch the lights on a schedule. Overall, the lighting in the NAR headquarters was modeled to consume 52 percent of the energy required by the modeled reference building meeting minimum ASHRAE/IES Standard 90.1-1999 requirements.

“The double-glazed curtain wall utilizes a new type of glazing,” says Sanden-Cabo. “Viracon Radiant Low-E insulating glass contains a coating that minimizes the transfer of heat through radiation and provides an improved shading coefficient. The curtain wall blocks nearly 90 percent of solar gain while enabling significant daylight penetration. Architectural shading is provided by a brise-soleil on the south elevation.”

BAS for HVAC
Controls play a leading role with the HVAC system, which is operated by a centralized building automation system and linked to the building’s fire alarms for automated response of the air-handling equipment during a fire. Variable-volume air-conditioning units vary the flow of air into the spaces based on outside temperature, saving energy. Adjustable-speed drives in the cooling and ventilation system save additional energy by adjusting operation closer to actual demand, with energy savings proportional to the amount of time the cooling system operates at less than full load. The building’s mechanical systems use nonchlorofluorocarbon refrigerants.

Intake of outside air varies based on carbon dioxide levels monitored at various locations. The air intake and exhaust points are located on the roof, well apart, to ensure the cleanest air intake and that the exhaust does not discharge into the immediate environment.

The energy design, consisting of lighting/HVAC/building envelope and modeled using the energy cost budget method in Standard 90.1-1999, resulted in 30 percent less power than a reference building designed to meet minimum Standard 90.1-1999 requirements.

Reducing Water Consumption
The NAR headquarters consumes 52 percent less water than a reference building modeled under Energy Policy Act of 1992 requirements, primarily due to waterless urinals, sensor-activated faucets fitted with 0.5-gpm aerators, and other low-flow fixtures, expected to save more than 880,000 gallons of water annually.

In addition, drains installed on the rooftop feed rainwater to a 10,000-gallon cistern in the basement, which supplies landscape irrigation and reduces consumption of potable water. The building is projected to collect more than 200,000 gallons of rainwater per year based on average regional rainfall.

“In general, the building systems employ standard products that are combined to form systems in support of the sustainable design requirements,” says Kevin Fallin, PE, principal, E.K. Fox & Associates Ltd., which provided MEP engineering for the project. “The waterless urinals require a minimal increase in maintenance to change the liquid seal cartridge four times per year. Otherwise, the operation of the building is no more complex than that of a standard office building design.”

The building also features environmentally friendly amenities including close proximity to public transportation, secure bike racks, electric-car charging stations, and preferred parking for cars that use alternative fuels.

Ensuring Efficiency
After the building was completed and NAR floors fitted, Paul Tseng of Advanced Building Performance commissioned the building systems. Commissioning ensures that all building equipment performs interactively according to the design intent and the owner’s needs, and can help ensure user acceptance and intended energy savings.

“The commissioning process provided valuable data for benchmarking the system performance in the future, as well as providing confirmation that the design met the project requirements,” says Fallin. “For example, the sequence of operation for the cooling tower was modified shortly after construction documents were issued. The commission process revealed that the operation of the cooling tower was not reflecting this revision. This finding allowed the engineers to address the operational issues prior to any adverse effects on the building.”

Sanden-Cabo concludes: “In concert with its unique sculptural forms, the building shapes the workplace through the integration of sustainable innovations. Conceived as a model of sustainability, the NAR headquarters will serve as an exemplary building environment for the future. A spectacular roof garden with panoramic views of the city, the use of recycled water features, and open workstations which optimize flexibility and climate control are just a few of the options available to devise a wonderful, comfortable, and extremely productive workplace.”

Craig DiLouie, a journalist, analyst, and consultant, is principal at ZING Communications Inc. (www.zinginc.com).

Owner: National Association of Realtors
Architect and Interior Design: GUND Partnership
Architect of Record: SMB Architects
Landscape Architect: Oehme Van Sweden & Associates
Engineer: CAS Engineering (Civil); Fernandez & Associates (Structural); EK Fox & Associates Ltd. (Mechanical/Electrical/Power)
Lighting Designer: George Sexton & Associates
Energy Consultant: Econergy International Corp.
LEED Consultant: GreenShape LLC.
Commissioning Consultant: Advanced Building Performance