Roofing’s Green Alternatives: There’s more to green roofs than merely white membrane

July 1, 2003
Maximizing Building Performance Through Environmental Strategies - PRODUCTS
Garden Roofs: The benefits of garden roofs, most commonly referred to as “green” roofs, are numerous. There are two types of garden roofs, intensive and extensive systems. Intensive refers to garden roofs with thick layers of soil ranging from six inches to six feet, which include large plants such as trees, shrubs, and perennials. Because of the structural load requirements of these systems, a concrete deck is required. The other garden roof type, an extensive, can be characterized by a few inches of soil, is not usually irrigated, and plant matter is more limited. Decking options include steel, wood, or concrete. Make sure to take the advice of professionals that can advise you on which option is most appropriate for your facility(s).Among the advantages reaped from garden roofs: Garden roofs help to minimize the urban heat island effect.Storm water runoff can be controlled effectively with garden roofs.Aesthetics of a building can be vastly improved with vegetated roof cover.Interaction with, or views to the outdoors and nature have been noted to positively impact productivity and promote the healing process.WORDS OF CAUTION: 1) “First and foremost, you’ve got to have a very good waterproofing system. If all the plants died and the roof didn’t leak, it would be okay. If all the plants were beautiful and the roof leaked like a sieve, you’ve got a major problem,” explains Brian Lambert, marketing manager, The Garland Co. Inc., Cleveland.2) “The systems do require more maintenance. Also, the roofing system has to be root-proof, so that the roots of the plants don’t thrive on the roof system or grow into the roof assembly. Otherwise, you’ve got a very expensive demolition and roof replacement,” warns Peter D’Antonio, waterproofing manager, Sarnafil Inc., Canton, MA.Photovoltaic Roofing Systems: If you think photovoltaics (PV) are a new technology, think again. “Most customers don’t realize that photovoltaics started being used extensively in space applications in the late ’50s and early ’60s,” says Edward J. Stevenson, CEO, Solar Integrated Technologies, Los Angeles. Depending on local incentives and the costs of power in your area, PV roofing systems can be an excellent way to be environmentally friendly and produce on-site power. “A typical cost per watt rate is ranging anywhere from $6 to as high as $15 a watt installed. However, the more power you generate, the lower your cost per watt to install is going to be,” says Larry Martof, product manager, The Garland Co. Inc., Cleveland.Benefits to PV systems include:A PV system can displace the amount of power required from utilities during peak hours.PV systems produce pollution-free power.A PV system can extend the life of your roof because PV modules shield harmful UV rays.The inclusion of a PV system increases property value.PV systems can minimize fluctuations in power, increasing power quality and reliability.WORDS OF CAUTION:1) Consider using a single-source provider of both the roofing and photovoltaic systems. “If you want to have your photovoltaic system stay on your roof, you’re going to want to have that mechanically fastened,” says Martof. “That’s going to require penetration, which could easily void your warranty, if you’re crossing between different manufacturers.”Metal Roofing: Metal roofing manufacturers have done the impossible, or so it seems. Offered now are roofs in colors like green, red, and blue that meet EnergyStar requirements for emissivity. Although it seems counter-intuitive, new color lines and high-reflectance pigments are changing the ideas that only white is green.A few of the benefits of metal roofing systems follow:You no longer have to compromise aesthetics to be green. Hi-R pigments are environmentally friendly and have the ratings to prove it.Both steel and aluminum roofing can be recycled, 100-percent post use. The products also contain a high percentage of recycled content.WORDS OF CAUTION:1) “The only compromise might be that we are absorbing a pigment cost increase of about three percent, for what is still called ‘exotic pigments,’” says Michael F. Petersen, president, Petersen Aluminum Corp., Elk Grove, IL. “My feeling would be that if the market acceptance takes off then that will commoditize itself to the point where there is no discernable cost difference to the end consumer.”For more information on this topic, contact the Metal Building Manufacturers Association ( at (216) 241-7333.Spray Applied Polyurethane Foam: Thinking it’s time to retrofit? Maybe you should think about Spray Applied Polyurethane Foam. The product’s durability makes it a sustainable option.Don’t overlook the benefits of Spray Applied Polyurethane Foam:Because it’s spray-applied, the foam fully adheres to the substrate, maintaining R-value ratings.Monolithic application means that there are no gaps, staggering joints, or seams – a real bonus in terms of energy conservation.The product can be applied over existing roofs, eliminating the need for tear-off and disposal in area landfills.The product has a long life, typically accompanied by a 15-year warranty. With recoating, the life of the system can be extended even further.WORDS OF CAUTION:1) Spray Polyurethane Foam requires a layer of acrylic, silicone, or urethane UV protective coating. Notes Tom Harris, product manager, Spray Applied Polyurethanes, BASF Corp., Wyandotte, MI., both urethanes and acrylics are EnergyStar labeled. “If you factor in durability, urethanes are the most durable. Acrylics are on the other end of the scale. If I want the best coating for environmental consideration, but I want something that is hail resistant and easy to maintain, then I need to choose urethane. If I want something inexpensive and I’m in Phoenix, I’ll go with the acrylic,” he says.

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