Green Roof Keeps United Therapeutics Cool

“This is our little urban oasis,” said Avi Halpert, Vice President of Corporate Real Estate at United Therapeutics as he showed the sixth floor green roof at their new headquarters building in downtown Silver Spring, MD.

The green roof is more a roof garden to the layperson’s eye. Full of flowers, grasses, and lush foliage, the planting beds on the fifth, sixth, and seventh floor of the at United Therapeutics building are full of movement and life. Plantings are embedded in the roof and are also raised in stainless steel containers.

There is plenty of seating and walking areas for United Therapeutics employees to enjoy a breath of fresh air during the workday and to hold informal meetings overlooking downtown Silver Spring to the south and outer suburbs to the north.

In part because of the extensive green roof terraces accessible from many of the offices, workstations and conference rooms, the National Capital Region Chapter of the U.S. Green Building Council has selected the United Therapeutics building as the recipient of its 2010 Award of Excellence for new Building Design and Construction. The Schick Goldstein Architect designed project was also awarded LEED Gold status in April 2010.

Green roofs have many benefits including holding in stormwater run-off and filtering out pollutants. Green roofs cool and humidify the surrounding air creating a microclimate in an urban heat island. They also keep building temperatures regulated especially in the summer.

A common concern about green roofs is that they may cause leaking problems. In actuality, green roofs have proven to be much stronger and more efficient than regular roofing materials at keeping water out. But, just in case, United Therapeutics has a back-up plan.

“We have lots of leak detection systems – moisture sensors built into the ceilings,” explained Halpert.

The building and green roof were completed just under two years ago. The green roof plantings were designed by renowned landscape design firm Oehme, van Sweden and Associates and they are maintained by Ruppert Nurseries.

“We wanted to show that green roofs can support a lot more than just sedums, “ said Sheila A. Brady, Principal, VP, FASLA at Oehme, van Sweden and Associates in Washington, DC. Brady designed the green roof gardens to include many native perennials that are low-maintenance and offer multiple seasons of interest.

“In just three inches deep of soil, it is amazing what you can grow and how much color there is,” commented Brady. The plant list includes coneflower, yarrow, lavender, salvia, alium, and various native grasses. Seventy-feet up the pollinators, such as native bees, have already found their way to the flowers and more wildlife is sure to follow. 

The second building in the United Therapeutics headquarters complex is now under construction and is on schedule to open this December. It will also have a green roof system along with other storm-water mitigation projects including a self-contained street tree box system. Across Spring Street, a playground and area is being designed to include a children’s garden for the new employee daycare.