Going green: from ground to rooftops

SIUE’s Student Success Center roof is turning green.  How green?  The green portion of the roof covers about 16,000 square feet.  Even several of the SIUE geese are loving it.

The roof of the SSC is part of a system of experiments that can also be found on the Engineering building, the chancellors patio on Rendleman Hall, and at a field site located near the SIUE police station.

The green roof on the SSC is a portion of a larger project facilitated at SIUE by William Retzlaff, associate dean of the College of Arts and Sciences and associate professor of biology.  The larger project is referred to as GREEN or Green Roof Environmental Evaluation Network.  Retzlaff states that the overall objective is to train students in the new technology of green roof systems.

The stated objectives, according to the GREEN website are to:

    • Evaluate the environmental benefits of green roof implementation;
    • Evaluate how green roof installation benefits the building owner;
    • Evaluate the performance of various green roof materials and techniques; and
    • Gather input from and disseminate information to interested parties.

(left to right) Students Daniel Murphy, Mark Ostendorf, and Roxanne Krutsinger take coverage measurements from the green roof on SIUE's Student Success Center.

Retzlaff, who also sits as the research chair for the trade organization Green Roofs for Healthy Cities, is part of a larger project team.  Other SIUE faculty involved are Susan Morgan, professor and chair of civil engineering, and Serdar Celik, assistant professor of mechanical and industrial engineering.

GREEN began as an initiative to study the worthiness of green roof projects and has expanded since then to incorporate the work of numerous students and faculty.

“The overall goal at the beginning was to find out if the concept of green roofs actually worked–do they provide the environmental benefits–and once we got that going, what is the best combination of things that work to do that,” said Retzlaff.  “From there, we’ve now had about 80 students that have done undergraduate and master’s theses projects on all our roofs.”

One student currently working on her senior project is Roxanne Krutsinger, a senior biology major “triple e” or ecology, evolution, and the environment.  Krutsinger has worked on a portion of the study that focuses on different methods to speed up the coverage by the planted sedums, even though she is more interested in the logistics of green roof projects.

“Most of their [other students] projects are looking at the environmental benefits of green roofs.  My project focuses more on the logistical side.  For instance, how do you either convince a client to get a green roof, or if they already have one and it’s not doing so well, can you fix the problem,” said Krutsinger.

A portion of the GREEN project, the ground level research site. photo courtesy of GREEN.

Environmental science second year master’s students Mark Ostendorf and Daniel Murphy are two other SIUE students involved in the project.  Ostendorf is looking at how green retaining walls can help with storm water runoff while Murphy is examining the thermal load that green roofs can take off of residential buildings.  The thermal load of a building is a portion of greening a building because it looks at how easy a building can be cooled or heated and what effect the roofing material and insulation have on the heating and cooling.  This is especially important during summer months.

“The black EPDM membrane that’s on most roofs gets up to 140 degrees Fahrenheit.  Underneath these [green roof systems], the rooftop temperature is only 80.  So, there is an enormous heat load difference on the building below.  Of course, that heat [from non-green roof systems] is then reflected back into the environment and the hotter it is, the warmer the city is.”

When the project was in testing phases, Retzlaff stated that they used a wind tunnel in the Engineering building to test different models.  This testing has helped set a national standard for green roof projects, according to Retzlaff.  The wind tunnel testing was given a “real world” test recently, as a small EF-1 tornado touched down in Granite City, Ill. created winds that rolled a large, heavy air handling fixture off of the roof of the SSC.  Retzlaff stated that none of the planting systems was even disturbed.

Recently, Morgan, Retzlaff, and a third researcher Isam Alyaseri, had an article stemming from this research published in the International Journal of Phytoremediation.  The article, titled “Suspended Solids in and Turbidity of Runoff from Green Roofs,” focused on another aspect of the study.  Retzlaff stated that the study aims to find out what kinds of materials are collected in storm water runoff from parking lots and different roofing materials.

GREEN also seeks to learn how biodiversity is sustained because of green roof systems.  Retzlaff stated that there is currently a pair of nesting geese on the roof of the SSC, as well as a killdeer nest with eggs.  Retzlaff stated that an undergraduate student worked on finding some answers to the biodiversity question.

William Retzlaff (left) talks with Daniel Murphy (right) about sustainability and the GREEN project.

“Last year, an undergraduate that was doing his senior year project found, just among the beetles and the spiders, 27 different species compared to out on the regular roofing there wasn’t anything,” said Retzlaff.

In the next year, according to Retzlaff, the biodiversity portion of the study will expand its range.  Retzlaff stated that there would be nest boxes installed that will allow the GREEN project to participate in a international study for cavity nesting bees.  These bees are predatory, meaning they hunt other insects, stuff them into cavities, and use them to feed their larvae.  This will help expand the biodiversity of the project by allowing researchers to find out how many species of insects are present on a green roof.

The green roof on the SSC was paid for by SIUE students as part of the green building features.  Although nearly two thirds of the SSC roof is covered, participants in the experiments are hoping to expand the coverage through private donations.

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