Virginia Tech Study Measures the Impact of Membranes on the Surrounding Environment

Equipment tripods are set up to hold air temperature and EMT temperature sensors.

Equipment tripods are set up to hold air temperature and EMT temperature sensors.

For much of the past decade, the debate over when and where to install reflective roofing has been guided by two basic assumptions: first, since white roofs reflect heat and reduce air conditioning costs, they should be used in hot climates. Second, since black membranes absorb heat, they should be used in cool-to-colder climates to reduce heating costs. This reasoning has been broadly accepted and even adopted in one of the most influential industry standards, ASHRAE 90.1, which requires reflective roofing on commercial projects in the warm-weather portions of the United States, Climate Zones 1–3.

But as reflective membranes have become more widely used, there has been a growing awareness that the choice of roof color is not simply a matter of black or white. Questions continue to be debated not only about the performance and durability of the different types of membranes, but on the impact of other key components of the roof system, including insulation and proper ventilation. The issue of possible condensation in cooler or even cold climates is garnering more attention. Given these emerging concerns, the roofing community is beginning to ask for more detailed, science-based information about the impact of reflective roofing.

One recent area of inquiry is centering on the impact of “the thermal effects of roof color on the neighboring built environment.” In other words, when heat is reflected off of a roofing surface, how does it affect the equipment and any other structures on that roof, and how might the reflected heat be impacting the walls and windows of neighboring buildings? Put another way, where does the reflected heat go?

THE STUDY

To help answer those questions, the Center for High Performance Environments at Virginia Tech, supported by the RCI Foundation and with building materials donated by Carlisle Construction Materials, designed and implemented a study to compare temperatures on the surface and in the air above black EPDM and white TPO membranes. In addition, the study compared temperatures on opaque and glazed wall surfaces adjacent to the black EPDM and white TPO, and at electrical metallic tubing (EMT) above them.

Specifically, the Virginia Tech study was designed to answer the following questions:

  • What is the effect of roof membrane reflectivity on air temperatures at various heights above the roof surface?
  • What is the effect of roof membrane reflectivity on temperatures of EMT at various heights above the roof surface?
  • What is the effect of roof membrane reflectivity on temperatures of opaque wall surfaces adjacent and perpendicular to them?
  • What is the effect of roof membrane reflectivity on temperatures of glazed wall surfaces adjacent and perpendicular to the roof surface?

To initiate the study, the Virginia Tech team needed to find an existing roof structure with the appropriate neighboring surfaces. They found a perfect location for the research right in their own backyard. The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech was selected as the site of the experiment because it had both opaque and glazed wall areas adjacent to a low-slope roof. In addition, it featured safe roof access.

In order to carry out the study, 1.5 mm of reinforced white TPO and 1.5 mm of non-reinforced black EPDM from the same manufacturer were positioned on the roof site. A 12-by-6-meter overlay of each membrane was installed adjacent to the opaque wall and a 6-by-6-meter overlay of each was installed next to the glazed wall. At each “location of interest”—on the EPDM, on the TPO, and next to the opaque and glazed walls—the researchers installed temperature sensors. These sensors were placed at four heights (8, 14, 23, and 86 centimeters), and additional sensors were embedded on the roof surface itself in the TPO and EPDM. Using these sensors, temperatures were recorded on bright, sunny days with little or no wind. The researchers controlled for as many variables as possible, taking temperature readings from the sensors on and above the EPDM and TPO on the same days, at the same time, and under the same atmospheric conditions.

The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech is the site of the experiment because it has opaque and glazed wall areas adjacent to a low-slope roof.

The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech is the site of the experiment because it has opaque and glazed wall areas adjacent to a low-slope roof.

THE RESULTS

The output from the sensors showed that at the surface of the roof, the black membrane was significantly hotter than the white membrane, and remained hotter at the measuring points of 8 cm and 14 cm (just over 3 inches and 5.5 inches, respectively). However, the air temperature differences at the sensors 23 centimeters (about 9 inches) and 86 centimeters (just under three feet) above the surface of the roof were not statistically significant. In other words, at the site the air temperature just above the white roof was cooler, but beginning at about 9 inches above the roof surface, there was no difference in the temperature above the white and black membranes.

On the precast concrete panel adjacent to the TPO and EPDM, temperatures were warmer next to the TPO than adjacent to the EPDM, leading the study authors to hypothesize that the TPO reflected more heat energy onto the wall than did the EPDM. Exterior glazing surface temperatures were found to be approximately 2 degrees Celsius hotter adjacent to the TPO overlay as compared to the EPDM overlay.

Elizabeth Grant led the team that designed and implemented the study. She says her findings show that you need to take the entire environment into account when designing a roof system. “You need to think about what’s happening on top of the roof,” she says. “Is it adjacent to a wall? Is it adjacent to windows? Is it going to reflect heat into those spaces?”

Samir Ibrahim, director of design services at Carlisle SynTec, believes the study results will help frame additional research. “These findings are an important reminder that the full impact of reflective roofing on a building and on surrounding buildings is not fully understood,” he says. “Additional research and joint studies, covering different climatic conditions, are certainly warranted to broaden the knowledge and understanding of the true impact on the built-environment.”

EPDM Can Meet FM 1-90 Ratings

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM.

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM, ideal for projects requiring FM 1-90 ratings. When the 6.5-foot-wide sheets are used in conjunction with HP-XTRA fasteners and HPXTRA Polymer Seam Plates at 12 inches on center, the system qualifies for an FM 1-90 rating over a grade C steel deck. The maneuverability of the sheets makes them suitable for smaller, cut-up projects, and the packaging (two rolls per core) reduces roof loading time and minimizes construction waste on larger, wide-open projects. The EPDM features 6-inch Factory-Applied Tape, which delivers value by improving the speed and quality of EPDM seam applications.

U-Anchor Solar Attachment System Withstands Hurricane

The U-Anchor 2000 has withstood another blast of hurricane force winds. The 800 kW Trina solar power generation system was secured to a Carlisle TPO roof membrane in a hybrid system, consisting of U-Anchor 2000 attachments and ballast solar racking on top of the Westin Dawn Beach Resort & Spa in St. Maarten. The system provides solar electric power to 317 guestrooms, restaurants, restrooms, laundry facilities and the spa.

The hurricane slammed into St. Maarten on Oct. 13 with no damage to the rooftop attachments and only minor debris-blown damage to the solar panels. Surrounding homes and boats were destroyed and the community’s water and power utilities reported outages. The solar electric power at the resort remained uninterrupted.

Hurricane Gonzalo was the second time the U-Anchor’s held a rooftop solar project securely in place while hurricane force winds blasted a rooftop solar project. U-Anchors shield a project on a large factory roof in Yonkers, New York, from 90 mph wind gusts during Superstorm Sandy in October 2012. Anchor Products completed the project in partnership with Sollega, Inc., which provided the ballasted racking portion of the hybrid system.

Anchor Products, LLC is the manufacturer of the U-Anchor 2000 patented rooftop solar attachment products for the attachment of solar equipment and accessories to ridged and flexible film roof membranes. When properly installed, the U-Anchor can withstand approximately 1,000 lbs of ultimate load force in tension, and approximately 2,000 lbs of ultimate load force in shear.

U-Anchor 200 can be used on ballasted or non-penetrating designs. U-Anchors maintain the roofing manufacturer’s warranty and can be quickly installed at a rate of 12 per man hour. U-Anchor 2000 and all of Anchor Products rooftop attachments come with an industry standard material warranty.

The U-Anchor line of products can also attach mechanical equipment, electrical conduit, plumbing pipes, HVAC ducting, satellite dishes, windscreens, lightning protection and antennas, among many others.

Hanley Wood Names Best Products from 2014 IRE

Hanley Wood Exhibitions has announced the selection of six products receiving recognition based on innovation, productivity and cost-effectiveness during the 2014 International Roofing Expo (IRE), held Feb. 26-28 at the Mandalay Bay Convention Center in Las Vegas. A panel of industry experts selected the “Best New Product” and “Best Sustainable Product” from selections found in the Product Showcase at the show.

The IRE Product Showcase, a 2,500-square-foot pavilion, featured 28 displays of the latest products focusing on safety and sustainability – as well as products made in the USA – in a direct, non-selling environment. Judges selected first, second and third place winners in each category.

Carlisle SynTec Systems of Carlisle, Pa., was awarded Best New Product for its Sure-Flex KEE HP PVC Membrane. ERSystems & Elastek of Irving, Texas, was awarded Best Sustainable Product for its ER One Step.

“The 2014 IRE was successful,” said Ryan Blad, Technical Service & Support for ERSystems & Elastek. “The biggest highlight would be OneStep winning the Best Sustainable Product Award.”

Second place in the Best New Product category was awarded to Galaxy Energy Americas of Aurora, Ontario, for its G7 universal standing-seam clamp, while third place was awarded to Metal Plus LLC of Winsted, Conn., for its Roofer’s Helper bracket.

Second place in the Best Sustainable Product category was awarded to Polyglass USA of Deerfield Beach, Fla., for its Polyfresko G SA, while third place was awarded to Freedom Supply of Wendell, N.C., for its Roofer’s and Paver’s Edge.

“We congratulate all six award winners,” said Tracy Garcia, CEM, IRE Show Director. “These companies deserve recognition for the innovative products they created and the significant impact each will have on the roofing industry.”

Other companies competing for the Best New Product award included AVM Industries, Benjamin Obdyke, DI Roof Seamers, Eco Chief Products, Epilay, ERSystems & Elastek, Insulation Solutions, Leister USA, Lifetime Tool and Building Products, MetalSafe Coatings, Polyglass USA, SafePro Guard, Tramex, Vector Mapping / IR Analyzers.

Competing for the Best Sustainable Product award were AVM Industries, Carlisle SynTec Systems, DaVinci Roofscapes, Eco Chief Products, Lifetime Tool & Building Products, Metal Plus and MetalSafe Coatings.

The 2015 International Roofing Expo will be held Feb. 24-26, at the Morial Convention Center in New Orleans. Online housing reservations can be made immediately and online registration will open in September.

Best Roofing Projects of the Carolinas

We celebrate the best roofs installed in North and South Carolina with our final issue of Carolinas Roofing. From metal to shingles to single ply and coatings, these roof coverings protect newly built and reroofed schools, homes, manufacturing facilities, city-service buildings and more.

Judy W. Rose Football Center-Fieldhouse and the McColl-Richardson Field Press Box, University of North Carolina, Charlotte

Judy W. Rose Football Center-Fieldhouse and the McColl-Richardson Field Press Box, University of North Carolina, Charlotte

Judy W. Rose Football Center-Fieldhouse and the McColl-Richardson Field Press Box, University of North Carolina, Charlotte

Team

Roofing contractor: Baker Roofing Co., Charlotte, www.bakerroofing.com
Designers: Jenkins-Peer Architects, Charlotte, www.jenkinspeer.com, and DLR Group, www.dlrgroup.com
Construction manager: Rogers PCL Russell, a joint venture of Rodgers Builders Inc., Charlotte, www.rodgersbuilders.com; PCL Constructors Inc., Charlotte, www.pcl.com; and H.J. Russell & Co., Atlanta, www.hjrussell.com
Metal roofing manufacturer: McElroy Metal, Bossier City, La., www.mcelroymetal.com

Roof Materials

New metal roofing matches the campus scheme on many other buildings. It also offers overall longevity, durability and low-maintenance features.

The field house and press box are covered with 11,000 square feet of Maxima 216, 24-gauge Kynar in Slate Gray and 4,000 square feet of 24-gauge flat stock metal roofing and low-slope roofing trim.

Roof Report

2013-14 is the first year for Charlotte 49ers football. This new 15,000-seat stadium was built for the new team and is designed to be expanded to 40,000 seats. The main building, the Judy W. Rose Football Center-Fieldhouse, located in the south end zone, has been named after the university’s longtime athletic director.

The stadium includes several other buildings, including the McColl-Richardson Field Press Box, named in honor of Hugh McColl, former Bank of America CEO, and Jerry Richardson, owner of the NFL’s Carolina Panthers.

Photo courtesy of McElroy Metal, Bossier City, La.

Pages: 1 2 3 4 5 6 7 8