First Green Roof in Walla Walla, Wash. Surfaces at Providence St. Mary Medical Center

The Tremco Roofing Sedum Mat System, with components supplied by Xero Flor, was installed on a 10,000-square-foot section of the Medical Center's new structural roof.

Using pre-vegetated mat technology, a 10,000-square-foot section of roof at Providence St Mary Medical Center was efficiently installed with a sustainable covering that according to hospital management will provide the facility with many benefits such as energy savings and better storm water management.

The initial green roof in this town in southeastern Washington will also present a pleasing vista for the patients whose rooms will look out over it.

"Providence St. Mary Medical Center needed to replace this roof and researched the benefits of adding a vegetated roof," says Larry Baer, the director of facilities. "This approach doubled the life of the new roof membrane. Air temperature reduction in the summer months, sustainable management of storm water, and an enhanced patient experience all contributed to our decision to install a green roof."

"The green roof will help the hospital meet its sustainability goals by conserving energy," said Elizabeth Hart of Tremco Roofing and Building Maintenance, one of the principals on the project. "Moderating temperatures on the roof and lowering the temperature of the air drawn into the rooftop HVAC units decreases energy use and utility costs."

In selecting a green roof system for the project, St. Mary's and its architect, Mahlum Architects of Portland Ore. placed high priority on immediate visual impact, ease of installation and low maintenance. The Family Birthing Center and the west side of the intensive care unit look out on the roof area. So an instant green roof featuring extensive vegetative coverage with mature, full-grown plants for immediate beauty was preferred.

"The pre-vegetative mats are grown for a full 9-12 months on independent, local farms, so the plants are mature and adapted to the regional climates where they are installed," said Clayton Rugh, Ph.D., general manager and technical director at Xero Flor America, the manufacturer of the roofing components. "Using local horticultural suppliers supports local economies, reduces the costs of shipping, and decreases the carbon footprint."