As construction for Project 2 marches on, the planning for the project’s final feature is underway: a green roof that will be built on top of the new facilities. A green roof is a roof of a building covered by vegetation planted in a growing medium, like soil, over a waterproofing membrane.
The Project 2 page on Oak Park River Forest High School’s website states that the green roof is being built to manage stormwater runoff, meaning any water that is not absorbed or stored somewhere after precipitation. Currently, OPRF stores excess stormwater in a facility under the outdoor track, but to meet codes set by the Metropolitan Water Reclamation District, they need further storage.
Due to the soil and plants, a green roof can absorb water and use it to nurture the plants, so less water will end up in the streets, where it could carry pollutants to water sources or erode structures.
OPRF Director of Buildings and Grounds Curtis Alsip said, “The green roof will increase the amount of water that does not go directly into the storm water system. It’ll still dissipate into the system, but not as fast. Like, when it rains on the street and it runs right into the gutters, a green roof system acts like grass, because it lets it permeate through it, not just run freely into the system.”
This will not be the only green roof in Oak Park, however. The Main Branch of the Oak Park Public Library had the village’s first major green roof installed in 2003. In a 2015 article published in the Wednesday Journal, Jim Madigan, the library’s assistant director for Administrative Services, said that the green roof had retained 194,354 gallons of stormwater per year, which was in line with the original intention. The Oak Park Public Works building also has a 10,000-square-foot green roof, installed in 2007.
Chicago has the most green roofs of any city in America, with 509 vegetated roofs throughout the city, according to data collected in 2013 by the city’s Department of Planning and Development.
The green roof at OPRF is not yet under construction, as it will be the last part of the project to be built due to being on the roof. According to Alsip, it is still in its planning stages, with architects and consultants working out “the size of the green roof system and what permitting allows.”
According to diagrams from FGM Architects, the firm overseeing the design of Project 2, the green roof will have a tray system, meaning the trays of growing medium with pre-planted vegetation, of approximately 7,820 total square feet.
Green roofs also have sustainability benefits. For one, they regulate the temperature of the structures they’re built on. The plants cool the air by absorbing water from the soil through their roots and releasing it as vapor through their leaves in a process called transpiration, as well as reflecting sunlight away from the building. This makes the building cooler, reducing the work that air conditioners have to do and the energy they have to consume. The layers of soil and vegetation also insulate the building, reducing the work that the heating system has to do. Both of these things lower the energy consumption of the building and make it more environmentally friendly.
Green roofs can also help cool the air around them on a hot day. Due to a phenomenon called the urban heat island effect, cities and suburbs tend to be hotter than rural areas. This happens because the abundant vegetation of rural areas produces a cooling effect while the dark pavement and metal buildings of cities absorb heat. Green roofs can mitigate some of that, making the cities they’re in more comfortable.
Cindy Wong, the teacher who runs OPRF’s Enviro Club, said, “I am most excited about the opportunities for education, outreach to the elementary school districts, and community engagement around the green roof. This is a win.”
Enviro Club co-president Owen Ruby, a senior, also had high hopes for the green roof, stating, “I think that an expansion of green spaces in OPRF is always a good thing, and it is in line with what we are doing with Project 2.”
He added, “Green roofs are nice because they provide a lot of sustainability upsides, and they provide a natural habitat for local wildlife. But also, there are a lot of structural benefits because it actually helps cool the school more, and helps save costs on roofing below because it protects it! Also, green roofs are just cool, and seeing more natural wildlife around OPRF would be very nice!”
