A new round of environmental regulations enacted to address growing concerns about climate change are inspiring roofing professionals to consider how commercial (low-slope) roof insulation can reduce a building’s environmental footprint. On Jan. 1, 2021, Canada and several U.S. states put into place new regulations eliminating the use of blowing agents containing hydrofluorocarbons with high global warming potential. The regulations apply to extruded polystyrene insulation and other closed-cell foam insulations that use HFC blowing agents in lowslope roof systems to support thermal performance, provide moisture control and deliver compressive strength.
Currently, the new HFC regulations are being implemented on a state-by-state basis in the U.S. The regulations are effective in California, Colorado, New Jersey, New York, Vermont and Washington, as well as Canada. At press time, Delaware, Maryland and Massachusetts have finalized regulations to lower the global warming potential levels of blowing-agent formulations that will go into effect later this year, and several states have proposed legislation. The regulations generally prevent the sale of noncomplying products into a state and allow a grace period for sales of existing materials after which noncompliant products cannot be sold. However, because of high demand during the pandemic, existing material is quickly depleting. As more robust environmental agendas take effect and the planet continues to experience more extreme weather events linked to climate change, adoption of more stringent environmental regulations may accelerate in the years to come.
Although the extent of climate change remains a subject of debate, the data points to clear trends. According to the Intergovernmental Panel on Climate Change, the United Nations’ body for assessing science related to climate change, the past three decades have been the hottest ever recorded on Earth. The levels of carbon dioxide in the air are greater than 400 parts per million, contributing to a rise in global temperatures. Human activity is credited with contributing about three of every 10 carbon dioxide molecules in the environment. This results not only in the basic need for more insulation to maintain comfort in the built environment but also leads to increased extreme weather activity and negative effects on the fragile ecosystem that ultimately affect the health, safety and welfare of Earth’s inhabitants.
As noted, increased temperatures result in more extreme weather, which ironically includes extreme lows as well as extreme highs. Record cold, ice and snow throughout Texas and many areas of the Gulf Coast contributed to a humanitarian crisis in February 2021. In 2020, extreme weather events, such as hurricanes and floods, also relentlessly affected the U.S. in different but devastating ways. The National Oceanic and Atmospheric Administration reported a record $22 billion worth of disasters striking the U.S. in 2020. Extreme weather left virtually no part of North America unscathed. NOAA reports 2020 was the fifth warmest year on record in the U.S. As these events become more frequent and extreme, it is imperative we do what we can to reduce the causes of this escalation.
The new HFC regulations follow a trend that supports sustainability and an escalating regulatory environment. Vegetative roof systems, often incorporated into low-slope commercial roofs, are a good example of fusing functionality with sustainability in the manufacturing of materials and environmental impact of the resulting roof through reducing rooftop heat islands, providing natural flora and fauna, reducing stormwater effects and extending the life of materials below a vegetative roof’s surface. Examples of high-performing vegetative roof assemblies can be seen coast to coast.
For example, acting as a gigantic 550,000-square-foot sponge, the Douglas A. Munro Coast Guard Headquarters building in Washington, D.C., absorbs rainfall while managing its release into the city’s sewer system. The roof system’s components, including extruded polystyrene insulation, help reduce rainwater runoff while also reducing pollutant loads and protecting natural resources such as the nearby Chesapeake Bay. Key performance objectives include complying with the city’s stringent stormwater regulations as well as Environmental Protection Agency rules requiring 95% of stormwater to be collected on-site. Washington, D.C., is a strong user of vegetative roof systems that make use of massive cistern systems, permeable pavements and bioretention vegetation. A good example of this approach can be seen in The Wharf, a public-private partnership spanning nearly 1 mile of the Potomac River and boasting a network of vegetative roof systems.
In addition to helping manage stormwater runoff, The Wharf’s vegetative roof systems are built as a protected roof membrane assembly with the waterproofing layer beneath the insulation and overburden. This helps support the development’s sustainability performance goals, which include reducing energy usage through daylighting, providing views and access to rooftop areas, and improving thermal performance through the heat reduction, cooling and shading properties of soils and plantings. Vegetative roof systems also can play a role in providing habitats for birds and other wildlife as well as reducing pollution in the immediate area.
Moving west, the Dickies Arena’s plaza deck helps manage Texas’ fierce weather as it brings a “sandwich” to the roof system design. As the roof’s structural slab slopes one way toward stormwater drains, the insulation rises and meets the bottoms of pavers or topping slabs, which slope in different directions to intermediate drains. Extensive modeling helped determine not only the placement of drains but also precisely how much insulation should be used, as well as its depth and location, in various parts of the plaza deck.
In addition to the drains that sit under the insulation, a network of drains placed on top of the insulation navigate the flow of stormwater runoff. On the surface of the pavers, linear drains serve as an open joint in the pavement, distributing heavy surface water falling on the plaza. Below the aesthetic and wearing surface, a second set of drains collects water at the waterproofing level above the structural slab. Sleeves and slopes work to drain this incidental water to the storm drain leading rainwater to the storm sewer lines. This intricate design allows for water management while maximizing design flexibility, reducing weight (as opposed to simply installing over a foot of concrete) and protecting the waterproofing membrane buried beneath the roof’s surface.
But there is more work to be done. The new environmental regulations and HFC bans have accelerated the pace of innovation for manufacturers to develop blowing agents with less global warming potential.
The blowing agent in extruded polystyrene foam insulation enhances thermal performance and can be tailored to a targeted density. Depending on the application, a project, such as a vegetative roof system or plaza deck, may require a higher density to deliver compressive strength while other projects, such as insulation in nonload-bearing walls, may favor a lighter-density material. In both applications, the blowing agent can tailor the polymer material to achieve a desired density and thermal performance.
Although blowing agents are an essential ingredient in extruded polystyrene foam, the processes that drive the material’s production also are important. As any chef worthy of his or her toque knows, even a small change to a recipe must be carefully evaluated in context with other ingredients and the various processes that create the final product. The same approach applies when it comes to selecting a blowing agent recipe that can meet more stringent environmental guidelines while delivering performance and complying with rigorous tests such as NFPA 285, “Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components.”
Finding the right recipe for a blowing agent formulation is no shortorder job. For more than six years, polymer scientists and researchers at Owens Corning, Toledo, Ohio, evaluated more than 100 blowing-agent formulations in concurrence with the company’s manufacturing processes. These insights informed recipe development and a proprietary process for manufacturing FOAMULAR® NGX™ (Next Generation Extruded) insulation. The changes in the manufacturing process were supported by investments in infrastructure and manufacturing assets.
The most daunting challenge in formulating an alternative to the legacy extruded polystyrene foam insulation was achieving the desired reduction in global warming potential while maintaining the wide portfolio of performance attributes, including a range of compressive strengths, high R-value per inch, moisture resistance, durability and even the company’s iconic pink color. And, of course, the new insulation had to deliver this performance over time, standing up to performance demands even as the planet experiences more episodes of extreme weather.
Owens Corning developed a calculator tool based on general data from the EPA and analyzing leading extruded polystyrene products that makes it easy for contractors and others to view a product’s environmental benefits. The calculator shows how replacing a traditional extruded polystyrene board with a next-generation offering can result in a significant reduction in carbon dioxide. Every 10 boards installed is equivalent to removing one car from the road for a year. When viewed through this lens, the savings metrics of a typical hospital project equate to 45,221,558 fewer miles driven, 6,199 tons of waste recycled instead of landfilled, 301,342 tree seedlings grown for 10 years or 2,324,183,946 fewer cell phones charged for a year based on information available at press time.
The way forward
Meeting future sustainability challenges demands an approach that adapts to and mitigates challenges ranging from extreme weather to increased regulations. A good starting point for roofing professionals is to become familiar with the regulations in the market(s) they serve. Given the U.S. reentering the Paris Accord and the Department of State’s initiation of the process to resume the Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer, it is conceivable a federal approach to banning these HFCs could replace the state-by-state patchwork model currently being deployed.
The roofing industry is poised to become an important player in the environmental arena as product innovations continue to keep pace with changing regulations.
For an article related to this topic, see "Stepping Forward", December 2018 issue.