Bringing Down the Roof

Temple University landscape architecture students design and build a ground-based green roof exhibit to make the campus green roof more accessible for learning.

by Robert Kuper, ASLA, Assistant Professor of Landscape Architecture, Temple University, and Mike Olszewski, PhD, Assistant Professor of Horticulture, Temple University

The ground-based green roof exhibit at Temple University?EUR??,,????'?????<

Look hard. Take your time. Walk around Temple University’s Ambler campus with the tallest available ladder in tow. Circle every building. You will not see the green roof. Ask students passing by if it exists or where it is. What becomes clear is that many students have never seen the campus green roof. Temple University’s “invisible” green roof, skirted with hickories, oaks, and locusts, is perched on the hill at the far reaches of the student commuter parking lot atop the Athletics Building.

The PECO green roof on the Athletics Building of the TUA campus sports inward-sloping wings and cover approximately 3,700 square feet.

There are no signs to direct you there. Few, if any, clues can be found on site. We realized that little could be done to make the green roof more visible for learning, except replicating a portion of it on the ground.

The Lexan panels step up and isolate each of six underlying green roof layers (plants, substrate, separation fabric, drainage layer, root barrier, roof membrane) to allow visitors to understand the basic construction of a green roof.

Exhibits next to green roofs are rare, but can offer many people the only direct access to a green roof they may ever have. Direct access is essential to green roof education. Currently, concerns about roof leakage, increased or extraordinary maintenance, incompatibility with existing roofs, aesthetics, and the possible inability of insuring property hinder widespread adoption of green roofs in the U.S. Most of all, developers and owners are concerned about high initial and long-term maintenance costs. Environmental and economic benefits such as the reduction of storm water runoff, the potential to decrease air temperatures in urban environments, the prolonged life of the roof membrane below the green roof and increased energy efficiency of the building must be emphasized if widespread installation of green roofs is to occur. One of the best ways to bring attention to green roofs, educate people about their benefits and encourage their adoption is by introducing examples. But the examples must be visible.

Cedar wood was used to construct the exterior frame of the exhibit. Pressure-treated wood was selected for the support structure and posts. Clear Lexan panels at the front and rear of the exhibit show beneath the surface of the growing medium and also protect the subsurface green roof layers.

The Athletics Building and its PECO green roof, approximately a 10-minute walk from the center of the Ambler campus or a three-minute walk from the student parking lot, is not integrated within the daily activities of students, faculty and staff. The W-shape of the roof makes the green roof difficult to see. Most visible is the center peak of the roof, covered by gray steel panels that express economy and efficiency rather than ecology and educated experimentation. The inward-sloping wings comprise the extensive green roof, together covering approximately 3,700 square feet. From the ground, the variety of sedums on the roof lay too low to interrupt the sharp, continuous line of the parapet and announce the presence of a green roof.

The detail drawing for the green roof exhibit reveals the materials, dimensions and footings. Excluding labor and the green roof layers donated by local suppliers of green roof materials, the exhibit cost $1,982.10.

To see that the roof is indeed vegetated, i.e., without being on the green roof, one must dodge careening vehicles speeding up the hill, cross the road leading to the commuter parking lot and stand on a mound directly in front of the building entrance. At that distance, the green roof is too far away to offer much insight into its construction, purpose and benefits.

To verify the assumptions we had about the roof’s visibility and potential educational value, we asked 118 Ambler students 13 questions to assess awareness of the PECO green roof and to understand their preferences for a learning tool. Since public/student access to the green roof is unsafe, we concluded the most practical learning tools were a ground-based green roof exhibit and a web camera mounted on the green roof. Most students who responded (95%) were aware a green roof existed on campus, but only about a quarter had visited the building. Some reasons given for not visiting the green roof: “Because it is not accessible. It’s at the far end of campus. I’m in a hurry to get to class and get home. It’s not visible from ground level.” Accessibility and visibility interested students most.

Although the questionnaire showed there was less interest in web camera viewing than direct physical access, one was installed on the northeast corner of the green roof and linked to the School of Environmental Design’s webpage http://mdev.temple.edu/webcams/amblercam/index.html.

The Temple University Ambler (TUA) campus (325 faculty and 3,5150 students) is located 15 miles from the main Temple campus in Philadelphia. In March 2000, the 187-acre campus, was officially designated an arboretum by the University Board of Trustees. TUA?EUR??,,????'?????<

A Ground-Based Exhibit Became the Focus

When a green roof exhibit became the focus of our efforts two landscape architecture students enrolled in an independent studies course spent approximately 10 to 12 hours per week for 30 weeks designing, experimenting, sourcing and purchasing materials and constructing the ground-based exhibit. Wood was selected as the dominant construction material based on cost, availability, aesthetics, durability, and the ease of manipulation. The length (8 feet) and width (4 feet) of the exhibit were based on the typical dimensions of milled lumber available at local lumberyards. The exhibit was sloped to allow for drainage and elevated to an accessible height for children and wheelchair-bound visitors. Learning from the exhibit requires displaying the underlying structures (i.e., waterproofing membrane, root barrier, etc.) for inspection. With that in mind, we decided the simplest way to show subsurface green roof layers would be through a series of stepped layers, each covered with clear polycarbonate panes. Polycarbonate panes were also installed in the front and rear of the exhibit frame to give visitors a view of plant rooting characteristics.

 

In snow or shine, the signs articulate the purpose of each green roof layer and potential environmental benefits. All signs were printed on 0.040-inch deluxe aluminum with polycarbonate laminate?EUR??,,????'?????<

In addition to showing the layers and the composite, seven brief, simple and attractive educational signs (one for the six layers and a general green roof introduction) were created. The colors selected for text and images were black, hunter green, and dark tan and placed against a white background to maximize sign visibility and legibility. All signs were printed on 0.040-inch deluxe aluminum with polycarbonate laminate—a thin, rigid material resistant to fading in long-term sun exposure—and affixed to the polycarbonate panes above each layer using silicone adhesive sealant.

All-in-all, the signs equal the exhibit in importance: they explicitly articulate the purpose of each green roof layer and potential environmental benefits.

We determined that the western side of the Athletics Building was the best location for the exhibit using the following criteria: (1) close proximity to the green roof; (2) compliance with the American with Disabilities Act; (3) safety issues related to nearby automobile traffic; (4) solar orientation; (5) amount of site work/grading and (6) visibility to pedestrians and motorists.

After the exhibit installation, a local design-build firm installed a path comprised of aggregate, modified stone screenings, and Belgium block edging. Excluding labor and the green roof layers donated by local suppliers of green roof materials, the exhibit cost $1,982.10.

The investment in our exhibit was well worth the cost. Few examples exist that are capable of easily showing and thoroughly explaining the composition of a green roof to people of many ages and abilities. Several times while monitoring the exhibit we met passersby. They inquired into what the exhibit was, what a green roof was and, most pleasing of all, stated they never before noticed the Athletics Building had a green roof. Comments such as these suggest that the exhibit has and can make people more aware of green roofs. Are they likely to return home and install a green roof? Maybe not. But if green roof examples become more numerous in the future, one of them might be right next door.

 

The ground-based exhibit also gives visitors a view of the wildlife green roofs attract.

 

Acknowledgements

Tim Garrett and Rebecca Kagle designed and constructed the green roof exhibit, having endured long-winded meetings and an overly ambitious schedule to create a valuable contribution to the Ambler campus and arboretum. To each, we extend our greatest thanks.

Resources

Calkins, M. 2005. Strategy use and challenges of ecological design in landscape architecture. Landscape and Urban Planning 73:29-48.

Earth Pledge. 2005. Green roofs, ecological design and construction. Schiffer Publishing, Atglen, Pa.

Getter, KL, DB Rowe. 2006. The role of extensive green roofs in sustainable development. HortScience 41:1276-1285.

Green Roofs for Healthy Cities. 2007. Final report, green roof industry survey 2006. Green Roofs for Healthy Cities, Toronto.

Smith, C and M Boyer. 2007. Who wants to live with a living roof? Green Places 39:24-27.