A multidisciplinary design and analysis for a green roof installation

Abstract

A multidisciplinary project is described in this paper that has produced a recommendation for the installation of a green roof on a campus building. A green roof is when plants are grown on top of a roof, which reduces the solar load on the air conditioning system and improves the sustainability of the design. The program within which this was done offers the Bachelors of Science in Engineering (BSE) degree, with five emphasis areas available to the students: mechanical, civil, electrical, industrial, and mechatronics. The emphasis area selected by a student determines certain electives but each student is free to take as many as four engineering electives in different disciplines, allowing multidisciplinary topics and even some elective courses at many levels throughout the curriculum. The building that this project addressed is one that until recently housed the Engineering Department with a flat roof design: poured concrete slabs supported by concrete beams, covered and sealed with black synthetic rubber membrane. There is roof access by both a stairwell and an elevator, so it would be an ideal building to install a green roof, since educational signage and tours would be easily accommodated. The design work for the green roof planters was done by two mechanical engineering emphasis students who were enrolled in a special topics course. The mechanical aspects of the design included the consideration of thermal and weight loads, specifications of the size, type and price of the planters and irrigation system and an economic analysis of the cost and potential savings. This design relied on structural calculations done by civil engineering students. To provide these structural calculations, students in one of the civil engineering emphasis electives, Structural Analysis, were given a series of assignments to determine the design loads acting on the building and the distribution of forces caused by those loads. Students in another civil engineering elective, Reinforced Concrete Design, were given assignments throughout the semester to determine the strength of the members of the roof and supporting structure. These assignments and example results are discussed in the paper. The final design report has been shared with the campus-wide Environmental Stewardship Committee and to the Physical Plant for consideration of the investment. This project is a demonstration of a service-learning effort that includes technical engineering analysis done in service to the university for the cause of environmental sustainability. © American Society for Engineering Education, 2014.