By Kat Harrold
Photo ~ By Green Roof Technology
For some, green roofs may seem a novel addition to a green minded institution but to Swarthmore College it was an essential and strategic move. In 2008 when the college needed to add a dormitory to accommodate its growing student body, there were concerns about the increased run off from the new construction. Sustainable architecture through green roofs offered a solution that minimized the building foot print making construction of the new dorm possible. The green roof was spear headed by a few brave faculty, dedicated alumni and students, and Green Roof Technology. To stay on budget the school chose to invest in a green roof instead of the costly LEED certificate while still building to LEED standards. This dorm was recognized in 2010 with the American Institute of Architects Housing Award.
The 8,600 sf green roof is the home to many plant species including sedum album murale, sedum spurieum roseum, delosperma nubigerum, and some indigenous plantings. The green roof also features a raised planting bed for experimental vegetation such as cacti.
The profile of the green roof is a shallow extensive system and has a total profile of 3.5 inches with the growing media depth composed of 2 inches. While Swarthmore may have a reputation for having the best maintained green roofs in the area, the maintenance required on the roof is blissfully minimal. To maintain its pristine state Gardener Lars Rasmussen weeds occasionally as needed and irrigates only when drought conditions exceed two weeks. The roof is minimally fertilized and occasionally cutting back of the overly aggressive plants takes place to encourage more diversity on the roof.
Since its installation the green roof has reduced run off, air pollution, and saved energy on the top floor of the building by as much as 25%. While the green roof is not available for students to congregate it is open for guided tours and classes and is visible to all from the third floor.