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Site Net Zero Mission

Architecture and engineering unite to create a truly energy-efficient building

Unisphere2
Photo: Halkin/Mason Photography LLC

For Silver Spring, Md.-based biotechnology company, United Therapeutics (Unither), buildings are seen as a physical manifestation of its values. The company, which focuses on the development and commercialization of innovative products that address the unmet medical needs of patients with chronic and life-threatening conditions, believes that sustainable design directly aligns with its mission of saving lives.

To achieve this challenge with Unither’s newest building, EwingCole, a national architecture and engineering firm based in Philadelphia, designed a site net zero building featuring 3,000 solar panels, a quarter-mile underground earth labyrinth, an atrium pool that acts as a heat sink, and more. The 210,000-square-foot, elliptically shaped “Unisphere” houses offices and clinical operations for pulmonary disease, heart failure and organ transplantation, as well as a virtual drug development lab.

Opened in September 2018, the six-story building is an expansion of Unither’s downtown campus. It is one of the largest net zero commercial buildings in the U.S., particularly significant due to its location in a dense urban area. The project features 75,000 square feet of structured parking, 10,000 square feet of retail space, and a 5,000-square-foot atrium. As a client, Howard Skoke, AIA, principal, EwingCole, says Unither is unique in that they are actively and enthusiastically involved in the design process. “They have a very open culture where all ideas can be explored, and this often leads to unexpected creative solutions. They are wonderful to work with because their team is 100 percent committed,” he says.

Photo: Halkin/Mason Photography LLC

Building Design

From the beginning, Unither had an elliptically shaped building in mind, given the site’s prominent location along a major roadway into Silver Spring. After branding the project “Unisphere” the design team was challenged to work with this strong geometric form to create the most sustainable, net zero energy building possible.

Jennifer Wampler, AIA, LEED AP, principal, EwingCole, explains that designers used an analog method in looking at the impact of different curtainwall details, floor-to-floor heights, and studying sun angles to see how they could maximize the solar exposure on the building’s south façade. The goal was to maximize solar production and daylighting while minimizing glare. “It was a really delicate balance of trying not to create shading where it would negatively impact solar panels, yet at the same time, allow light to flow through the building,” she says.

This process informed the building sections, Wampler notes, adding that they found that leaning the building back and tapering it in so that each floor gets a little smaller as it goes up, gave the best exposure on the solar panels and also minimized shading. And, since many of the building components have dual purposes—both functional and aesthetic—the solar panels were no exception. “The solar panels function as an awning to temper the summer sun,” she adds, “and also to create a strong architectural rhythm on the south façade.”

Photo: Halkin/Mason Photography LLC

Achieving Net Zero

Unisphere consumes approximately half the energy of similar buildings in Silver Spring, and all energy is produced on-site. “We couldn’t use any of their adjacent properties,” says Wampler, “and we couldn’t use any energy off-sets. It really had to be truly self-sustaining.”

As Skoke explains, Unisphere was a complex project to model, due to the many architectural and engineering variables that needed to be tested to reduce energy demand and achieve net zero. “This was a great opportunity for our design team since the project criteria turned out to be so exacting,“ he says.

The building’s location on a limited site in an urban environment was also a challenge, especially when it came to the use of geo-exchange wells to increase the building’s efficiency. Geo-exchange wells act as a heat exchanger with the earth, cycling hot or cold water used in the HVAC system. By doing this, the efficiency of the HVAC system is increased between 25 and 50 percent. To fit the 52 required geothermal wells on the tight project site, Unither worked with the state of Maryland to allow location of geo-exchange wells underneath the building footprint.

In addition to adding solar panels and geothermal wells, natural ventilation was also introduced as an energy-reducing component, according to Wampler. “Refining the energy model was an ongoing process throughout the design,” she says. “It was a highly integrated effort, and much of the architectural design was generated by engineering solutions.”

The building’s natural ventilation system works in three stages: automatic, manual and mechanical assist. When outdoor conditions permit, the window below the raised access floor at the building perimeter and above the ceiling at the central atrium, open to provide a cross flow of air. The atrium acts as a thermal chimney, using the buoyancy of warm air to induce airflow throughout the building. Occupants can also manually open windows for individualized comfort.

Photo: Halkin/Mason Photography LLC

Automated Building Systems

The building features a centralized building automation system that reduces building energy by optimizing system performance, setting occupied and unoccupied modes, and setting back temperatures in areas where possible. The system also interfaces with lighting controls and power monitoring. Incorporating energy meters on the building’s various systems provide valuable feedback for benchmarking and trending, allowing the building operation to be modified in real time and the energy effects observed.

To help visualize the Unisphere’s energy use, Brooklyn, N.Y.-based experiential/graphic design company, HUSH, designed an energy dial on display in the atrium. In the shape of a giant sundial, it is made up of 24 silver markers connected by beams of light. “The wheel uses light and mirrors, reflecting either inward or outward depending on the amount of energy that’s being used and how much is being produced,” Wampler explains. “If the light is facing inward, then the building is using more energy that it's producing. If the light is facing outward, it’s producing more energy than it’s using. It’s a very abstract representation of live energy data, kind of an energy heartbeat of the building.”

The energy dial is supplemented with a variety of visual messages throughout the office floors that explain the building systems and its components. “It’s a flash card story of how Unisphere achieves net zero,” says Skoke.

Photo: Halkin/Mason Photography LLC

Metal Palette

Metal is used prominently throughout Unisphere and connects the new building with the first two buildings on the campus. Skoke says the material palette was determined years in advance, as part of master plan guidelines. “The first building has metal, curtainwall and terra cotta panels,” he explains. “The second building dropped the terra cotta in favor of metal and curtainwall, although the colorization and proportions of the metal mimics the terra cotta panels. The north façade of Unisphere is a continuation of the first two buildings and metal panels help to create a unified composition along the street.”

For the project, Austell, Ga.-based MillerClapperton supplied over 108,000 square feet of 4-mm Reynobond metal composite material wall panels with an FR core in four colors. This includes 1,621 panels in Silversmith, 176 panels in custom Pewter, 72 panels in custom United Red and 769 panels in custom Terra Cotta. MillerClapperton also supplied 0.190-inch aluminum plate grille fin panels. This includes 108 panels in Silversmith, 10 panels in Pewter, and 27 panels in Terra Cotta, all of which feature paint matching from Finishing Dynamics, Villa Rica, Ga. Arconic Architectural Products, Eastman, Ga., supplied the Reynobond metal composite material.

Additionally, MillerClapperton supplied 16,500 square feet of perforated metal panels, which were engineered for the sail feature on the bow of the building and in the atrium. The company also installed a custom canopy on the loading dock from Rusco Custom Canopies, Knoxville, Tenn., and approximately 1,500 square feet of louvers from Construction Specialties Inc., Lebanon, N.J.

FRENER & REIFER America Inc., New York City, supplied the curtainwall and glazing systems, while Faribault, Minn.-based SAGE Electrochromics Inc. supplied its electrochromic glass for the building. The combination of increased insulation, triple-paned glazing and electrochromic tinting glass creates a 25 percent thermal improvement over minimum code values. The electrochromic glass changes its level of tinting based on the season, location of sun, cloud coverage, glare from surrounding structures, and occupant preference. It also helps reduce the amount of thermal energy entering the building.

The solar tray is another prominent metal component. Solar panels are attached to the standing seam metal roof from CENTRIA, Moon Township, Pa. The underbelly of the tray is made up of orange metal panels that continue from the exterior through the inside of the atrium for great dramatic effect. Additionally, the majority of the ceilings throughout are metal perforated plank panels from Hunter Douglas Architectural, Pearl River, N.Y.

Photo: Halkin/Mason Photography LLC