The Ohio State University, one of the largest universities in the US, is dedicated to advancing education, research, and innovation for energy and the environment, emphasizing how those needs can be met sustainably. Ohio State supports “campus as a test bed” activities, in which the university is a resource for testing and improving new industrial technologies; helping faculty teams to obtain research funding; improving campus operations; and engaging students in cutting-edge sustainability science.
A landmark example of how the university campus serves as a “living laboratory” is the Howlett Hall Green Roof, the first publicly accessible green roof on campus located within the College of Food Science and Technology, Agricultural Administration, and Horticultural and Crop Science. The green roof is part of the university’s Chadwick Arboretum and Learning Gardens, a 60-acre public garden at OSU. The installation was completed in the summer of 2013, which represents the first retrofit green roof on campus serving as a demonstration project promoting the benefits to both students and the community.
The 12,000 square-foot green roof was installed in August and September on the back of Howlett Hall, over the building’s extended ground floor. Previously, the roof was accessible through a first-floor conference room, which had been built with a doorway to allow people to step out onto the roof. The roof had been meant to house a rooftop greenhouse since the building was dedicated in 1967 according to Mary Maloney, Director of Chadwick. The old roof was leaking, blighted, and in general disrepair requiring a full replacement. Ohio State provided a plan that was to place the green roof on top of the new roof as soon as it was installed. A goal of the Arboretum for many years, the roof was a tar and chip roof that was hot and unattractive, as well as an under-utilized space on the urban campus.
NBBJ’s landscape architects participated in an open design charrette that included a group of over twenty designers, horticulture advocates and academic representatives which spawned numerous design possibilities. NBBJ then volunteered to assist the Chadwick Arboretum maintaining the ideas and momentum generated in the charrette by establishing a process that led to evaluation of the various concepts and distillation of the ideas that transitioned to a graphic presentation used for fundraising purposes. Ultimately the arboretum went through an interview process that lead to NBBJ being hired to advance the design of the roof space and develop construction documents for its implementation. Working closely with the Chadwick Arboretum’s Steering Team and the University, NBBJ developed design options that looked at a long term build out of the roof along with strategies for phasing. Initial concepts explored how the space could create outdoor rooms which provided extensive and intensive roof garden prototypes along with structures for green walls of various types that could be analyzed and then experimented with over time. The roof design provides pathways, gathering areas and a series of planting beds that will also be utilized by the public when completed.
Once the new conventional roof was completed in August, work began on the green roof. First, the new roof’s membrane was covered with a heavy-duty protection fabric, with an aggregate drainage layer installed over top of that. Existing drains were replaced with new fittings, so any rainwater that the plants don’t use will be well drained. Then, about 4-6 inches of lightweight growing medium, engineered specifically for green roofs, was added and mounded in some areas to add interest to the rooftop landscape, along with circular walking paths. The plants were planted in September and include many drought-tolerant species such as: Blue Fescue, Geum Tangerine, Coreopsis, Achillea (Yarrow), Black-eyed Susan, Talinum calycinum, Prairie Dropseed, Lavender, Allium cernuum, Sempervivum Black (Hens & Chicks), Thyme (four varieties) and Sedum (18 varieties).
Chadwick Arboretum raised more than $400,000 for the green roof project through donations and grants, including one from the EPA. The green roof itself cost about $200,000, with an additional $50,000 for the new guardrail and another $100,000 in pre-construction design and engineering. With its completion in September, the roof has become a beautiful garden respite with several sustainable benefits, including:
- Mitigation of 200,000 gallons of polluted stormwater from the Olentangy River each year
- Reduction of heating and cooling costs for the food science pilot plant below the roof
- Adding biological diversity in the urban environment from insects, birds and bees
- Lengthening the lifespan of the new roof to 40-50 years by protecting it from the elements
An additional feature is that irrigation of the roof garden is supplemented by rain water collected into bladders from the adjacent greenhouse roofs. The green roof provides for an excellent opportunity to expand their present gardens and create a unique garden that can be used for education and research of green roof technologies by students and faculty at an attainable cost standpoint.
This realization of the Howlett Hall Green Roof reinforces the university’s values as a member of the American College & University Presidents’ Climate Commitment and establishes a resource for green roof research that will have far reaching influence on renovation of existing campus facilities as well as new.
*Story via NBBJ. Photo credits: 1,3 – Sherrill Massey, 2 – Jodi Miller, 4-6 John Woods.