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Crowning Achievement: An environmentally sound roofing system tops an environmentally
Developed by the city of Chicago as part of its seven-year-old brownfield redevelopment effort, the Midwest Center is a model of sustainable renovation. The 28,000 square foot center occupies a former manufacturing building that was once part of a rock-crushing company. Along with its conservation-minded construction, the facility is also envisioned to be a showpiece of sustainable industry. Sharing the site are a manufacturer of carbon-free solar energy equipment, and the city’s job training and community gardening program. Applying even a handful of "green" building techniques to such a major brownfield redevelopment project might have been noteworthy enough. But the City’s Department of the Environment (DOE) sought to integrate as many sustainable building practices as possible to achieve the highest score provided under the United States Green Building Council’s Leadership in Energy & Environmental Design (LEED™) rating system. To meet the city’s goal, architects at Farr Associates of Chicago applied their expertise in green design. The building materials contain significant recycled content and were manufactured less than 300 miles from the site. Energy-efficient lighting and power systems minimize power consumption, and construction debris from the renovation process was recycled on and off-site. The project team also had ambitious goals for the roofing system, and not just because it would support an array of solar panels supplying 20% of the building’s electricity, as well as a rooftop garden. The specifications called for minimum R-40 requirement for the insulation to maximize energy conservation. Although conventional insulation could have met this specification, the design team wanted to use an environmentally-sensitive product that would reflect the Midwest Center’s goals. The answer was ACFoam®-II with ACUltra™ from Atlas Roofing Corporation. Unlike other types of insulation produced using hydrochlorofluorocarbon (HCFC) blowing agents that deplete the earth’s ozone layer, ACFoam®-II is part of Atlas’ ACUltra™ family of polyiso roofing products manufactured using hydrocarbons (HCs). The result is a commercial insulation product that provides the same level of performance as conventional products at the same price, but at no cost to the environment. "Environmentally speaking, polyiso has always been a plus, since its high thermal value helped to reduce fossil fuel consumption," explains Atlas Roofing’s Technical Manager, Richard Roe. "However, there was a down side: CFC-11 and HCFC – 141b contribute to ozone depletion." This balancing act changed for good after the Montreal Protocol banned the use of CFC worldwide in 1994 and permitted industries to manufacture HCFCs, which have approximately 90% lower ozone depleting potential, as an alternative blowing agent only until January 1, 2003. Atlas researchers immediately began experimenting with different formulations that would meet the stringent environmental requirements without altering polyiso insulation’s other important properties such as high per-inch thermal values, compressive strength, and dimensional stability.
Although ACUltra™ products have been widely used throughout the construction industry since being officially introduced in 1998, many roofing contractors have not yet worked with the new material. "Unless you’re familiar with how it’s made, you’d swear it’s the same insulation," says Kevin O’Reilly of North Coast Commercial Roofing Systems, which supplied ACFoam®-II for the Midwest Center project. "From the contractor’s perspective, there’s no difference whatsoever in the handling, appearance, weight, or performance." "We’re pleased to be involved with this new and innovative product," adds Paul Cronin, Vice President of Knickerbocker Roofing Company of Harvey, IL, the Midwest Center’s roofing contractor. "It may well be the insulation of the future."
Project Superintendent Jack Kenny has high praise for Atlas Roofing’s customer support. "Atlas is very conscientious about its shipping and product," he says. "They will always call a day or two before delivery to make sure we’re still on schedule. What’s more, the product sizes are always consistent and easy to work with. They are by no means a commodity manufacturer."
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Project Information Client: Related Products
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Remember the old saying, "actions speak louder than words"? When it comes to environmentally friendly building design and construction, the Midwest Center for Green Technology makes a statement strong enough to be heard around the world.
Tests of hydrocarbon mixtures eventually yielded ACUltra™, which has zero ozone depletion potential and zero global warming potential. Those results and proven performance in other projects around the country were perfect for the Midwest Center. And because Atlas’ East Moline, IL, facility had recently been converted to the ACUltra™ process, the ACFoam®-II panels could be produced and shipped toChicago from less than 200 miles away, earning the Midwest Center additional points under the LEED rating system.
Work got under way on the Midwest Center’s new 15,000-square-foot roof in late autumn of 2000. After removing the existing multi-layered surface, Knickerbocker’s roofing crews nailed a Siplast Parabase base sheet on a poured-in-place gypsum deck, and covered it with a mopped-in-place Parabase base sheet. Next came the tapered layers of ACFoam®-II, which are sloped 1/8-inch per foot. The insulation’s thickness increases from six inches at the low points to 9-1/2 inches at the high points. The insulation was then covered with panels of Georgia Pacific Dens-Deck gypsum roof board. Workers then mopped down a Siplast Paradiene 20 base ply, followed by a torched down Paradiene 30 modified bitumen membrane across most of the roof. For the area beneath the rooftop planters, Knickerbocker applied two Siplast products-Paradiene 20 membrane and Teranap modified bitumen waterproofing ply.
Construction of the Midwest Center for Green Technology is set for completion in the spring of 2001. O’Reilly is also pleased to see ACUltra™ utilized successfully in such a high-profile project. "As a key distributor of polyiso products, we find it beneficial to have a partnership with a manufacturer who is on the leading edge of technology," he says. "Atlas Roofing Corporation has proven to be that kind of organization.Knickerbocker’s Jack Kenny sums it up in a typical Midwestern understatement: "I have a feeling that ACUltra™ insulation will be around for a while."