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United Therapeutics is a biotechnology company. It believes that sustainable design aligns directly with its mission of saving lives. The company also views its facilities as “strategic assets” in attracting and retaining top talents.

The project, named Unisphere, is one of the largest net-zero commercial buildings in the US. 



Unisphere is located in a dense suburb of Washington DC, with hot, humid summers and relatively cold winters. The site is surrounded by mid-rise buildings constructed to the vertical zoning limit. Getting to net zero is challenging, especially for a  commercial building with gross floor are of more than 12500 m2 (excluding parking space).

Energy modeling was used to guide the early design decisions. From the beginning, an elliptical shape was chosen to minimize the east/west exposure and maximizing the north/south exposure. Each successive floor is a little smaller than the floor below it to maximize the solar access for the facade-mounted solar panels. On the south facade, the solar panels not only generate energy, but also function as shading devices.

Almost all of the office spaces are illuminated significantly with daylight. 



Central to the operation are 52 geo-exchange wells drilled 500 feet into the earth that function like heat pumps. Water-filled pipes buried underground pull heat from the earth in the winter to heat the building and then send heat from the building back into the earth during the summer to cool it.

The central atrium includes a thermal pool that also serves as a source of evaporative cooling and heat rejection.

To increase energy efficiency, Unisphere employed an integrated building automation system that can monitors and controls HVAC, lighting, power metering, the electrochromic glazing of the windows, the public feedback system and photovoltaic monitoring.



Company officials won’t talk publicly about the cost of creating a net-zero building. But Thomas Kaufman, director of corporate real estate for the company, said the price wasn’t much more than some of the company’s earlier buildings.

“The technology is off the shelf,” he said. “We didn’t invent anything new. It just required the mindset to make it happen.”







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