Skip to main content
Sister Publication Links
  • European Rubber Journal
  • Plastics News
web
Subscribe
  • Login
  • Register
  • Subscribe
  • News
    • ITEC
    • Automotive
    • Tire
    • Non-Tire
    • Suppliers
    • Silicone
    • Latex
    • Coronavirus
    • Executive Action
    • Government/Legal
    • Opinion
    • Technical Notebooks
    • International Elastomer Show
    • Women in Tire & Rubber
    • HEXPOL Sponsored Content
    • Goodyear recognized by Lockheed Martin as 'elite supplier'
      EV tire advancements to help secure future
      Lambillotte: Only question on AVs is timing
      CAR official says EV future brighter than autonomous
    • Goodyear-branded transmission belts set to return
      Hot topics at virtual CES: AVs, air taxis and drones
      Apollo to raise prices of Vredestein brand tires
      China's tire production up in 2020
    • Greenergy, Haldor Topsoe tech turns tires to fuel
      India decides against extending carbon black duties
      GRI expanding ag tire capacity at 3-year-old Sri Lanka plant
      Apollo to raise prices of Vredestein brand tires
    • NewAge Industries celebrates 15 years of employee ownership
      India decides against extending carbon black duties
      WCCO task force navigates pandemic, expands communications
      JobsOhio funding gives Sperry & Rice room to grow
    • Safic-Alcan and Arkema working together on distribution deal
      India decides against extending carbon black duties
      Biesterfeld to supply Denka acrylate rubbers
      Ace Products & Consulting partners with Wallace Instruments
    • Ace Products & Consulting partners with Wallace Instruments
      Safic-Alcan extends distribution agreement with Momentive
      Momentive aims to grow silicone presence in Asia-Pacific region
      IRP Medical solidifies portfolio with KDL deal
    • WCCO task force navigates pandemic, expands communications
      ASTM cancels April meetings as COVID-19 continues impact
      Paycheck Protection Program funding reopens Jan. 15
      Detroit Auto Show canceled; alternative event being planned for September
    • ARP Materials adds technical sales manager
      Jack Murphy joins Akron Dispersions
      Adriano Alfani named Versalis CEO
      Maroon Group adds to Southeast sales team
    • India decides against extending carbon black duties
      Hot topics at virtual CES: AVs, air taxis and drones
      Paycheck Protection Program funding reopens Jan. 15
      Taiwan tire makers propose settlement of import duties case
    • Column: Pandemic looms over everything in life, business in 2020
      Column: Lessons from the 2020 Best Places to Work
      Editorial: Silicone hit hard by pandemic, expected to bounce back
      Column: Still far way from normal
    • Effects of multiple repurposed materials for reinforcements of standard rubber compounds
      Impact of peroxide blends on the cure rate and aged properties in HNBR
      Techniques to detect long chain branching in polymers
      A comparative study looking at effects of curing kinetics and batch variation on SBR injection molding and numerical analytics
    • Rubber Division seeks abstracts for 200th Technical Meeting
      WORD panelists say evolution, authenticity keys to success
      IEC keynote: Communication key to logistics
      IEC speaker: Specialized elastomers may reduce spread of life-threatening pathogens
    • WORD panelists say evolution, authenticity keys to success
      New video celebrates women in rubber industry
      ITEC panelists say women can thrive in tire industry
      Rubber Division planning second Women of Rubber event
    • Sponsored By HEXPOL Compounding
      Faster Access to Your Polymer Compounding Experts Around the World
      Sponsored By HEXPOL Compounding
      Take a walk thru a HEXPOL Lab
      Sponsored By HEXPOL Compounding
      HEXPOL offers a unique selection of High Performance Elastomers to match your application requirements
      Sponsored By HEXPOL Compounding
      It’s what you can’t see that makes the Difference at HEXPOL
  • Blogs
    • Products
    • Wacky World of Rubber
    • New Products: MonTech introduces 1,500 kN lab press
      New products: 3M introduces new durable, pliable medical adhesive
      New Products: Lanxess launches energy-efficient PU elastomer
      New Products: MonTech automates bale cutter for safety, productivity
    • Wacky World of Rubber: How Trelleborg, teens sealed a spot in the world record book
      Wacky World of Rubber: Of chicken and feet, but not chicken feet
      Wacky World of Rubber: Time to go mattress shopping
      Wacky World of Rubber: Because nothing says football like 'frunk' shrimp
  • Newsletters
    • Rubber in Automotive
    • Silicone News
    • Latex News
    • Sign Up for Newsletters
    • Goodyear-branded transmission belts set to return
      Hot topics at virtual CES: AVs, air taxis and drones
      Apollo to raise prices of Vredestein brand tires
      China's tire production up in 2020
    • Ace Products & Consulting partners with Wallace Instruments
      Safic-Alcan extends distribution agreement with Momentive
      Momentive aims to grow silicone presence in Asia-Pacific region
      IRP Medical solidifies portfolio with KDL deal
    • Jack Murphy joins Akron Dispersions
      Synthomer optimistic, raises earnings forecast
      Top Glove reopens COVID-hit factories with enhanced precautions
      Malaysia electronics group to enter rubber gloves sector
  • Multimedia
    • Videos
    • Photo Galleries
  • Directory
  • Resources
    • Classifieds & Mold Mart
    • Sponsored Content
    • White Papers
    • Sponsored By HB Chemical
      The Company Behind the Inventory
      Sponsored By French Oil Mill Machinery
      Process Improvement, Cost Reduction with Custom Press Systems
    • Sponsored By Uncountable Inc.
      Cooper Standard deploys lab informatics platform to synchronize R&D
      Sponsored By Elkem
      LSR Select™: A solution to improve your financial impact in molding applications
      Sponsored By HEXPOL Compounding
      Understanding and Selecting Performance Additives for Rubber Compounding
      Sponsored By HEXPOL Compounding
      Peroxide Cureable Silicone Injection Molding
  • Data
  • Events
    • RPN Events
    • RPN Livestreams/Webinars
    • Industry Events
    • Past Events
    • ITEC Library
    • International Silicone Conference Library
    • 2021 Healthcare Elastomers Virtual Edition
      2021 Rubber in Automotive Virtual Edition
      2020 International Silicone Conference Virtual Edition
      2020 ITEC Virtual Edition
  • Advertise
  • DIGITAL EDITION
MENU
Breadcrumb
  1. Home
  2. News
December 11, 2013 01:00 AM

Up on the rooftop: Debate continues—EPDM vs. TPO

Chris Sweeney
  • Tweet
  • Share
  • Share
  • Email
  • More
    Print
    Workers install a Firestone RubberGard R.M.A. System, an EPDM roof. Firestone makes both EDPM and TPO roofs.

    When it comes to roofing, one size does not fit all.

    A plethora of options dictate what kind of membrane, level of insulation and installation method should be used in the construction process. But one choice seems to spark more debate than the rest: The battle of black versus white, as in black EPDM surfaces against white reflective—usually thermoplastic polyolefin or PVC—membranes.

    Each has its advantages and works in a variety of situations. But to do so, a number of other variables must be taken into account and, in some cases, overcompensated for.

    When membrane—or any roofing variable—gets promoted as a quick environmental fix, the EPDM Roofing Association takes exception.

    “Roofs are based on a variety of factors,” said Ellen Thorp, associate executive director of the ERA. “To dictate one of those variables without an intimate understanding of that building's location, usage or number of occupants is short-sighted. All of those things go into what kind of a roof to put on there. A roof designer is the best person to help make those decisions.”

    Jeff Henegar, director of research and development, Firestone Building Products, said the typical break line for using white versus black is the Mason-Dixon Line. According to Weather Data Depot's calculator—and using a commonly adopted standard base temperature of 65°F—in 2012 Chicago had 5,166 heating degree days to 1,262 cooling degree days.

    New York City had 4,068 heating days to 1,195 cooling, and Pittsburgh had 4,837 heating days to 972 cooling days. Generally speaking, buildings in those cities spend more time keeping their respective buildings warm than cold.

    And all three cities are making a push for expanded use of white reflective roofs. Henegar said either membrane can be effective, but that doesn't mean it is necessarily the best choice for the situation.

    The cool choice

    Cities have a growing concern for what's called the urban heat island effect, citing studies that show excess heat generated by the structure of the city—human activity and the presence of dark, impermeable surfaces—traps heat within the city and raises its temperature in comparison to the surrounding rural areas. White roofs are being push-ed as a way to combat this effect.

    “There's been concerns throughout various larger cities in the U.S. that these darker surfaces—be it the road, the parking lot or the roof—contribute to elevated temperature in those cities,” Henegar said. “They felt the easiest way to try and attack some of that is by mandating the use of white roofs in those locations.”

    The Global Cool Cities Alliance is a non-profit founded in 2010 that works with cities around the world on understanding the issues around urban heat islands. It works with cities to identify whether or not it has a heat island and how big it is, and it connects the city to experts in the industry to develop strategies to help mitigate that heat island.

    According to Executive Director Kurt Shickman, the most economical of those options is cool roofing.

    “At the end of the day, you have to make a building-by-building decision in terms of design and what's going to work on an individual building,” Shickman said. “Generally I think cool roofs are the best choice for cooling down a city, reducing the AC load in a building and helping to reduce the amount of surface heat on or being blown off the roof. But my organization doesn't advocate for turning everything white as soon as possible. We want the buildings to be designed well and to meet what we think is an important social and environmental goal for cities.”

    Unfortunately for the ERA, regulatory bodies do not share Shickman's philosophy. Department of Energy Secretary Stephen Chu said in 2010 that cool roofs are “one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change.”

    At the same time, Chu and President Obama committed to reduce its greenhouse gas emissions 28 percent by 2020. Chu directed all DOE offices to install cool roofs when constructing new roofs or replacing old ones on DOE facilities, whenever cost effective.

    With the federal government taking the lead, other cities have followed suit, even those in the northern climates.

    “There is certainly concern among manufacturers, JM included, that legislation brought to light too fast may not offer the best solution for people in those regions,” said Rick Gustin, product manager for EPDM at Johns Manville Inc.

    Chicago was ahead of the curve. The city implemented an ordinance in 2008 requiring most new roofs and roof renovations to use white reflective materials. The ordinance was updated to include ballasted roof systems.

    New York City recently strengthened its building code to require expanded use of white roofing material. It also established the NYC CoolRoofs Initiative, a program that paints black roof surfaces with a white reflective paint designed to help reduce energy use.

    While white roofs are not required by the state of Pennsylvania, they are beginning to gain traction in Pittsburgh. The Children's Museum installed a white roof in 2004 as part of a museum expansion program, and earlier this year the city launched its own cool roofs program to paint the surfaces of 10 city-owned buildings with reflective paint.

    Mike DuCharme, director of product marketing at Carlisle Syntec, doesn't think paint programs make sense in the northern climates. He cited a study that demonstrated a higher degree of moisture accumulation among white roofs in northern climates when compared to black EPDM counterparts. If all things are equal, changing the coating of the roof changes the dynamics of the building.

    “What was working might not now work with that same building,” DuCharme said “Maybe it has enough humidity within the building that now you start to get condensation when you didn't have it before. You go from the one that was performing with good energy efficiency to one that has saturation insulation, poorer energy efficiency and maybe a premature roof failure.”

    Thorp said if facility managers want to change the color of a roof, they must take into account the number of occupants, type of insulation and the assembly.

    “We want the decision of what roof to use to be a joint decision between the building owner, the facility manager and the architect or the designer,” Thorp said. “Those are the people who should be making the decision about what sort of roof system to use.”

    A worker installs Firestone's UltraPly TPO roofing membrane.

    Other variables

    The membrane color is only one part of the roofing equation. Each roofing manufacturer stressed that insulation plays a bigger role in making environmental strides.

    “Insulation is still the lion's share of the difference,” DuCharme said. “When you compare different levels of insulation to the white versus black option, insulation by far is going to be what drives your energy efficiency. Whether the sun is out or not, whether it is night or day, insulation is going to provide a benefit, whereas color will not.”

    The American Society of Heating, Refrigerating and Air-Conditioning Engineers is one regulatory body that mandates a minimum amount of thermal resistance insulation that products need for a building to meet code. The minimum required thermal resistance of a product—or R-value—is calculated based on climate zone. Most minimum standards start at R-20 for the warmer zones in the U.S. and usually reach around R-35 for the colder ones, but cities and municipalities can raise the minimums on their own accord.

    Henegar said from the minimum R-value, designers can add more layers of insulation to increase the building's conservation of energy, minimizing the impact of the choice of membrane color.

    “Many of the government mandates that require white roofs are done so under the guise of energy efficiency,” Thorp said. “But the fact of the matter is if you have proper insulation, you can be just as energy-efficient with a dark colored roof in a southern climate.”

    DuCharme said that on average, when using an EPDM roof in the southern climate or a white reflective roof in the north, insulation should be increased by an R-value of 3-5, which isn't a huge burden on the cost of the roof. However, the need to overcompensate for condensation can impact the cost of a white roof in a northern climate.

    Henegar said the real impact of white roofing is the potential for reflectivity to take some of the thermal load off in the summer, but in areas with cold winters it offers no real value one way or the other. He said there are arguments that darker roofs make more sense in colder climates because it helps melt the snow off and take some of that burden off the roof structure.

    “A well-designed roof takes into account the type of vapor drive within the building and the type of usage,” Henegar said. “Typically as long as you're designing with vapor and air barriers within the system, white membranes will be effective in the colder climates. The thing you have to be concerned about is moisture drive in the cooler months and having condensation in the roof.”

    And that's where the cost goes up. DuCharme said that white reflective roofs have a higher potential for condensation in colder climates and usually has to be combated with an air barrier. He estimates that an air barrier could add as much as 30 percent to the cost of the roof.

    A black EPDM roof has the ability to handle temperature swings better, is more flexible and absorbs heat in the winter months, which DuCharme said minimizes the accumulation of ice and moisture.

    “We manufacture EPDM, TPO and PVC,” DuCharme said. “I do think that EPDM is the best performer from a longevity standpoint. We base that on lab testing that indicates to us that EPDM should have a life cycle of 40 years.”

    TPO does not have the history of EPDM. Gustin said the jury is still out on whether or not total lifecycle costs of the product will wind up being superior to EPDM.

    “A lot of studies are in motion at this time, and we're certainly seeing that this might not be the case in all buildings,” Gustin said. “I think JM and other manufacturers are advocating for building-by-building approach as opposed to a blanket one-size-fits-all piece of legislation that may be a good solution for most, but not all.”

    Ultimately, the ERA stresses that no one variable can determine whether or not a roof will be energy efficient or cost effective. What works in one state cannot be applied universally across the U.S. because of variances in climates, building sizes and frequency of use.

    “We try to encourage our policy makers to be well versed on a variety of research studies,” Thorp said. “There's always one or two favorite studies policy makers like to look at. We encourage everybody to look at a wide variety of research.”

    Related Articles
    Fed agency gives OK to LEED competitor
    Roofing group champions EPDM
    Rubber roofing still has legs
    Rubber roofing still has legs
    GAF wins two web marketing awards
    Precision Polymer develops steam resistant material
    Group takes issue with roofing study
    ERA makes recommendation to EPA on environmental guidelines
    ERA takes issue with proposed guidelines
    ERA praises ICC's decisions on roofing proposals
    TPO boom spurs expansion
    Letter
    to the
    Editor

    Rubber & Plastics News wants to hear from its readers. If you want to express your opinion on a story or issue, email your letter to Editor Bruce Meyer at [email protected].

    SIGN UP FOR NEWSLETTERS
    EMAIL ADDRESS

    Please enter a valid email address.

    Please enter your email address.

    Please verify captcha.

    Please select at least one newsletter to subscribe.

    Get our newsletters

    Staying current is easy with Rubber & Plastics News delivered straight to your inbox, free of charge.

    Subscribe Today

    Subscribe to Rubber & Plastics News to get the best coverage and leading insights in the industry.

    SUBSCRIBE
    Connect with Us
    • LinkedIn
    • Facebook
    • Twitter

    MISSION

    To serve companies in the global rubber product industry by delivering news, industry insights, opinions and technical information.

    web
    Contact Us

    2291 Riverfront Pkwy, Suite 1000
    Cuyahoga Falls,
    OH 44221

    Customer Service:
    877-320-1726

    Resources
    • About Us
    • Digital Edition
    • Contact the Staff
    • Advertise
    • Order Reprints
    • Privacy Policy
    • Privacy Request
    • Terms of Service
    • Careers
    • Ad Choices Ad Choices
    • Sitemap
    Partner Sites
    • Tire Business
    • European Rubber Journal
    • Plastics News
    • Plastics News China
    • Urethanes Technology
    • Automotive News
    • Crain Brands
    Copyright © 1996-2021. Crain Communications, Inc. All Rights Reserved.
    • News
      • ITEC
      • Automotive
      • Tire
      • Non-Tire
      • Suppliers
      • Silicone
      • Latex
      • Coronavirus
      • Executive Action
      • Government/Legal
      • Opinion
      • Technical Notebooks
      • International Elastomer Show
      • Women in Tire & Rubber
      • HEXPOL Sponsored Content
    • Blogs
      • Products
      • Wacky World of Rubber
    • Newsletters
      • Rubber in Automotive
      • Silicone News
      • Latex News
      • Sign Up for Newsletters
    • Multimedia
      • Videos
      • Photo Galleries
    • Directory
    • Resources
      • Classifieds & Mold Mart
      • Sponsored Content
      • White Papers
    • Data
    • Events
      • RPN Events
      • RPN Livestreams/Webinars
      • Industry Events
      • Past Events
      • ITEC Library
      • International Silicone Conference Library
    • Advertise
    • DIGITAL EDITION