Spring might be bringing green in some unexpected places.
There are quite a few green roofs across Northeast Ohio, and the list is growing. In 2002, the Geauga Park District opened the West Woods Nature Center that included a green roofed service building. The green roof has served as a pilot project for the Park District to study the benefits of green roof construction and technology.
Cleveland’s first historic green retrofit building, the Cleveland Environmental Center in Ohio City, included a portion of green roofing in 2003. The original plans for Cleveland State University’s Recreation Center included a 7,000 sq ft green roof when it was built in 2006, but the plans were scrapped when the project ran out of funds. In 2009, students in an Environmental Science class raised money and the project was completed.
This past fall, Cleveland Botanical Garden staff, landscape architects and Bill Doty of Doty & Miller Architects installed a 1,920 sq ft living roof on a portion of the existing roof outside the Eleanor Armstrong Smith Glasshouse. The project is part of the National Sustainable Sites program through which the Garden will test the first rating system for sustainable landscapes. Interpretation will be added for visitors to the Garden and there are plans for the roof to be accessible and visible to the public.
Modern green roofs are either intensive or extensive systems, depending on the material used. Intensive green roofs are limited to flat surfaces and have a deep substrate layer that can support a variety of plants, as large as trees. These roofs are often accessible to people and can require a great deal of maintenance, similar to a ground-level garden. Extensive roofs have shallow substrate layers, support a limited number of plants, such as grasses or draught tolerant succulents, require minimal maintenance and do not tolerate food traffic.
Either system offers many benefits. These include decreased stormwater runoff; decreased impermeable surfaces, which helps reduce the urban heat island effect; and increased insulation in cold climates and absorption of heat in hot climates, which affects a building’s energy use. Green roofs also extend the useful life of a roof while offering an aesthetic value and habitat for wildlife.
Some concerns in using green roofs include the cost to implement and maintain systems; the complexity of the systems and the repair and upkeep difficulties they might present; climate or weather restrictions; building structure, roof slope and loading considerations; growing medium and plant selection; and irrigation requirements.
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