Project Management Institute

Balance of Power

Unisphere's Massive Net-Zero Building Delivers ROI that's Good for the Grid

Balance of Power



Unisphere building in Silver Spring, Maryland, USA



Not even the best-laid plans could guarantee that a project to build one of the world’s largest net-zero energy commercial buildings would deliver on its ambitious promise. “We worked hard on the energy model,” says Jason Fierko of EwingCole, the design and engineering firm that created the new 210,000-square-foot (19,509-square-meter) headquarters for biotech company United Therapeutics. “But until the data comes in, you just don’t know.”

Now they do. More than a year after the Unisphere building opened in Silver Spring, Maryland, USA, the facility is well on its way toward achieving net-zero certification by demonstrating that it uses no more energy than it produces for a full year.

The building generates all of its electrical and thermal energy via on-site renewable energy systems. In the first nine months, it returned 237,192 kilowatt hours (kWh) of energy back to the grid—enough to power nearly 23 U.S. homes per year. Fueled by solar panels and a vast mix of other renewable energy technologies, the project has exceeded energy-swap expectations.

Net Gains

The Unisphere building is exceeding environmental expectations. The energy balance after the first nine months of operation:


Sources: EwingCole and United Therapeutics


The pool in the building’s atrium. At right, solar panels cover a side of the building


“We are trending about 23 percent below the modeled consumption, which is good,” says Mr. Fierko. As EwingCole’s director of energy practice, Philadelphia, Pennsylvania, USA, he was responsible for making sure the building would meet its energy goals. Among other factors, he attributes the performance to the fact that some aspects of the system are operating better than expected. A small portion of the building is not occupied, so energy use could increase as those spaces are filled.

It also helped that United Therapeutics founder Martine Rothblatt, PhD, drove a relentless pursuit of net-zero goals. From the moment Dr. Rothblatt tapped EwingCole to launch the project in 2011, there was a never-surrender team culture, Mr. Fierko says. “A project like this has no room for naysayers. Having the right mix of people with the right skills and attitude was key to our success.”


—Jason Fierko, EwingCole, Philadelphia, Pennsylvania, USA


Because EwingCole already completed smaller net-zero buildings, project leaders knew they had to find contractors and vendors who were able to embrace a first-mover mindset. From the start, all team members had to challenge assumptions and work collaboratively to anticipate surprises, says Jared Loos, CEO, EwingCole.

“It came down to quality, attitude and approach,” Mr. Loos says. General contractor Whiting-Turner “had never done a project quite like this before, but they were great collaborators, and when we faced problems, they came with solutions.”

Energy performance drove all decisions—and even altered the scope. Most prominently, the team capped the size of the building based on how much energy it could generate. “From a zoning perspective, we could have made it 100,000 square feet (9,290 square meters) larger,” says Thomas Kaufman, director of corporate real estate, United Therapeutics, College Park, Maryland. “But we were limited by our solar energy generation capabilities.”

The team also had to ensure the immense scaling of other renewable infrastructure technology didn’t violate building codes. For example, the geothermal heating system required the team to drill 52 wells 500 feet (152 meters) under the building. “The owner had to lobby for a regulation change to make it happen, but it’s just one more example of how this project blazed new trails,” Mr. Loos says.


—Jared Loos, EwingCole

Addition by Subtraction

The Unisphere team implemented these tools to achieve energy-leveling benefits:

3,000 solar photovoltaic panels generate 1,175 megawatt hours of energy each year—enough to power 100 homes.

52 closed-loop, dual-circuited geo-exchange wells were drilled 500 feet (152 meters) under the building to provide energy storage.


Concrete tunnels 12 feet (3.6 meters) below ground provide natural ventilation and passive temperature moderation.


An atrium pool acts as a heat sink for excess hot air, which helps to balance the overall temperature in the building and provides passive heating of pool water.


Automated daylight harvesting dims artificial lighting when adequate sunlight is available. Perimeter offices require no artificial light at least 70 percent of the time.


Electrochromic glass technology on office windows automatically adjusts tint level based on season, location of the sun and cloud coverage.


Automated windows and panels open and close to naturally ventilate the building, providing a completely passive ventilation system between certain temperatures.


Grid connections allow the building to sell excess power to the grid during peak production times and to draw power from the grid at night and at off-peak times.


Unisphere is flush with smart-building technology that controls the environment and energy use through a fully automated network, including real-time dashboards that monitor performance around the clock. As a result, it can instantly adapt to deliver maximum comfort with minimal energy use.

Creating this system required the team to rethink its entire workflow, Mr. Kaufman says. In a typical building project, the controls contractor is one of the last contractors to come on board, and the systems integration happens in a black box, with very little visibility and oversight from the owner. As a result, nobody knows whether everything will work, which means big changes can be disruptive and expensive, he says. Since energy use was the most important key performance indicator, they knew that waiting until the last minute was simply too risky.

Instead, project managers brought the system integration team in during the early shop drawing phase so they could plan the automation system in conjunction with the building. Then the team built a mockup of the entire system in a warehouse to test it. “We wanted to make sure it could be controlled the way we envisioned,” Mr. Loos says. “By building it on the front end, we were able to work out all the kinks before any concrete was poured.” PM

Braced to Erase

Universities and housing developments around the world are also looking to wipe out their carbon footprints.


University of Dubai

Project: The first LEED-certified net-zero energy building in Dubai, United Arab Emirates

Net benefit: The campus achieved the status in November 2019 through the addition of a US$1.47 million solar power project, which will result in nearly US$330,000 in energy savings within its first year of operation. The solar system is connected to the national grid, eliminating the need to use batteries for energy storage.


National University of Singapore School of Design and Environment

Project: The first net-zero energy building in Singapore

Net benefit: The university last year opened doors on a six-story facility that features 1,200 solar panels, generating 500 megawatts of energy per year—slightly more than the school expects the building to use. An overhanging roof creates additional shade and helps keep rooms cool.


Pontardawe, Wales

Project: A net-zero neighborhood

Net benefit: The £8 million project will build 35 net-zero homes, each of which will feature solar panels, ground-source heat pumps and innovative ventilation systems. The team plans to break ground on the site this year, with homes completed in summer 2021.

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