RoofViews

Building Science

Overburden

June 15, 2022

Since its inception a roof's primary purpose has been to shelter its inhabitants from the elements, but now the underutilized potential of roof surfaces is being realized. For roofs with large surface areas, the potential for large overburden installations, such as solar, vegetative roofing, or amenity decks can be exceptional. Even smaller roofs can have overburden that make a significant impact on the sustainability goals of a building including: increased energy efficiency, stormwater retention, energy generation, biohabitat restoration, food production, reduced urban heat island effect, and outdoor space.

However, selection of the overburden system is only part of the design. Selection and design of the roof membrane, the waterproofing layer that protects the building, is critical for a long-lasting installation. Failure of the membrane, whether it requires repair or replacement, may necessitate removal of the overburden. The removal of the overburden can result in lost energy generation for solar installations, and loss of rainwater capture for both vegetative and blue or purple roof assemblies. Appropriate selection of the entire assembly, including proper detailing and integration of the roof assembly, as well as installation, are paramount to the overall success and longevity of the overburden system.

Overburden Assemblies

Roofing overburden is defined as "any manner of material, equipment or installation that is situated on top of, and covering all or a portion of, a roof or waterproofing membrane assembly."^* This excludes thermal insulation but includes: planters, vegetative roof assemblies (both trays and built-up), loose gravel, water tanks, void fill (like EPS, XPS, and/or Polyiso rigid foam), tiles, pavers, supporting pedestals, equipment, and solar PV arrays.^*

While each property is unique, there are many overburden options and roof assembly considerations to meet sustainability goals.

Vegetative Roofs: Vegetative roofs are plants that are installed in trays or built in-place on the roof with extensive or intensive plant configurations. Tray systems and extensive roofs are generally in depths of less than six inches and consist of shallow rooted plants, such as sedums. Intensive vegetative roof systems have deeper soil depths and can accommodate larger plant installations.
Blue Roofs: Blue roofs are systems that are designed to provide stormwater detention. Rainfall onto the roof is managed using orifices, weirs, or other outlet devices that control the discharge rate of rooftop runoff.
Blue-Green Roofs: A blue-green roof is a blue roof with a vegetative roof assembly.
Purple Roofs: A purple roof is a "sponge" roof that incorporates a sponge-like layer made of hydrophilic mineral wool, a dense polyester fabric detention layer, and may or may not include an additional honeycomb layer to increase the volume of rainwater that can be retained and detained .
Rooftop Solar: Solar PV panels come in both single sided and bifacial (double-sided) modules. A bifacial module can produce power from both sides thereby increasing the energy generation. Modules are supported by racking systems on the rooftop that are either mechanically attached to the roof, mechanically attached to a structural canopy that is attached to the roof, or held in place with ballast.
Agrivoltaics: The emerging practice of agrivoltaics, or agriculture combined with photovoltaics, is showing promise as a mutually beneficial symbiotic solution to not only increase the efficiency of solar panels, but also increase plant size and crop yields by shading and limiting soil evaporation

Roofs have the potential for many types of overburden installations including vegetative assemblies, plaza decks, and incorporation of multiple types of assemblies.

Roof System Considerations

Selection of the roof membrane, the waterproofing layer that protects the building, is critical for the success of overburden installations. The membrane performance and roofing assembly configuration, including location of the membrane in the assembly must be considered. Improper selection of membranes can result in leaks, costly repairs, or even replacement. Special considerations like the type of insulation and cover board should be explored. Most importantly, the roof system should have a lifespan that is equal to or greater than the overburden system. Membrane performance is not only dependent on the overburden and associated roofing assembly materials, but also the design and installation. Roof assembly selection and specific design details down to the last termination and penetration detail should be provided to ensure the roof is installed in accordance with the contract documents.

Membrane Selection

Single-ply membranes can be an excellent choice for overburden installations as they can be used at the deck level and at the top of the assembly. Membranes that will be used at the deck level, such as for vegetative assemblies, should be evaluated for durability and longevity since access to them for repairs will be limited. Solar is typically installed directly on the membrane. For blue roofs and water catchment systems, single-ply membranes are commonly used at the top of the assembly and it is recommended that single-ply membranes meet NSF P151 water standards.

Membrane Color

For roof assemblies where the membrane is exposed and at the top of the assembly, such as for solar panel installations and blue roof assemblies, the color can have a significant impact on the performance of the system and also on the roof surface temperatures. Reflective roof membranes can lower the ambient roof temperature. Using a lighter colored roof can decrease the urban heat island effect in cities, and also may decrease the amount of heat that is able to radiate into a building's interior.

For solar panel installations, light colored or reflective roof membranes can lower the ambient roof temperature which allows the panels to function more efficiently. The temperature of a PV panel can significantly impact how much electricity the panel produces; as panels get hotter, they produce less power. According to an article published by GAF, "It is estimated that the efficiency of a PV panel can be up to 13 percent higher when installed over a highly reflective membrane compared to a dark membrane with low reflectance. Also, the use of bifacial PV panels over reflective roof membranes can increase the efficiency by 20-35 percent, as they take advantage of the reflected light.

For overburden installations, such as blue or purple roofs where the membrane is exposed, reflective membranes are also advantageous. Even though the roof may not always be holding water, or presumably when water is present it is translucent, a reflective membrane contributes to lower roof surface temperatures. Additionally, vegetative roof systems can take advantage of reflective membranes where vegetation is not installed. Codes require that borders and paths are maintained on the roof for fire, access, and maintenance. Reflective membranes at these locations may lower roof temperatures which mitigates interior heat gain, and also decreases the strain of summer heat on vegetation.

For solar panel installations, light colored or reflective roof membranes can lower the ambient roof temperature which allows the panels to function more efficiently.

Membrane Thickness

Roof assemblies should be installed to match or exceed the service life of the overburden systems. The risk of installing a less robust system, such as with a thinner single-ply membrane, could require roof replacement prior to the end of overburden's service life. An unprotected roof membrane should offer enhanced protection against the effects of UV, high service temperatures, punctures, and added foot traffic to help ensure that the roof's life and overburden will match. For single-ply membranes, thicker membranes can provide protection against punctures from the extra foot traffic for overburden service and maintenance. Single-ply membrane thickness significantly improves impact resistance (such as by dropping a tool) by almost 80 percent from 45 mil to an 80 mil membrane. A thicker single-ply membrane also provides additional protection to both UV and high surface temperatures, which is important since a thicker overall membrane provides more thickness over the scrim (reinforcing layer). This portion of the membrane provides weather resistant properties, including UV resistance.

A roof membrane in an IRMA assembly should have added protection to punctures and abrasion from roof elements above it, including root damage in a vegetative assembly. For installations where the membrane is on top, it is a best practice to install walkway pads around solar arrays or exposed areas of single-ply membranes to protect against the added foot traffic to service the installations.

Membrane Attachment

There are two broad categories of roof attachment; mechanically attached via use of fasteners, and adhered.

Attachment methods should be reviewed for ease of installation and energy efficiency. Energy efficiency roof assemblies can be directly related to thermal bridging, which occurs when components allow for heat transfer through the roof assembly. Heat loss means that the mechanical equipment will have to work harder to maintain the desired interior temperatures. Thermal bridging occurs at gaps or discontinuities between materials, such as at fasteners in a mechanically attached system. Particularly where the fasteners penetrate the entire assembly from the membrane through the insulation and into the deck, the fasteners provide a direct thermal path from the exterior to the interior.

Mechanically attached single-ply systems are also subject to billowing in high wind events. Billowing, or fluttering, of a membrane is when wind causes a negative pressure by pulling interior air into the roof assembly creating uplift force on the roof assembly. Over time, it can cause stress and fatigue on the mechanical attachments and membrane. Interior air that is pulled into the roof assembly equates to energy loss since often the temperature controlled air may warm or cool based on the temperature of the membrane. Overburden installed over mechanically attached systems may billow and flutter with the roof membrane during high wind events. As the membrane flutters and moves, the overburden will shift on the membrane, causing abrasion of the membrane surface. The overburden may also experience stress and fatigue due to movement, which could decrease their overall service lives.

Adhered system where only the first layer of insulation is mechanically attached, significantly reduces interior air loss and thermal bridging.

Adhered systems that do not use mechanical fasteners greatly reduce thermal bridging by eliminating the path from the interior of the roofing assembly to the exterior. Adhering also prevents billowing of the membrane, by mitigating the interior air that can be brought into the roof assembly.

Insulation

Insulation is critical in roofing assemblies for overall energy efficiency of the building. The higher the R-value, expressed per inch, the better the thermal performance of the insulation and its effectiveness at maintaining interior temperatures. Higher R-value per inch means less material is required to achieve the desired insulating value. In overburden systems, the roof system thickness can have an impact on the overall design of the overburden system. For example, roof flashings need to extend a minimum of 8-inches past the completed installation. For vegetative systems, this means that the flashing must extend 8-inches past the vegetation. Flashing heights are of particular importance at mechanical curbs and parapets. For a new construction installation, it is possible to raise the heights of the curbs and parapet walls to the desired height, however, in an existing building, this can be problematic.

Insulation boards should be installed so that the joints are staggered and offset, and several layers of insulation should be installed rather than just one thick layer. Gaps between boards can decrease insulating ability by allowing thermal loss, an increased condensation potential if air travels into the roof assembly. Air brings moisture, which if allowed to condense, can saturate the insulation boards. Wet insulation has an R value of approximately zero, which is like having no insulation at all.

Staggered and offset insulation board joints.

Coverboards

Inclusion of a coverboard must be considered after selection of the overburden. Rooftops with overburden assemblies not only have increased foot traffic on the roof, but are also an added dead load on the roof assembly. High traffic areas should always be protected with walkway pads. Adding a high-compressive-strength coverboard below the roof membrane will enhance system protection, including compressive strength. Coverboards provide added protection against penetration, including tools dropped by service contractors, wind-borne debris, and hail. A thicker coverboard increases its penetration resistance. The use of high-density polyiso insulation coverboards should be considered since they not only add protection to the roof assembly, but also add an R-value of 2.5 per half-inch.

Overburden Layout, Details & Flashings

Qualified design and construction professionals should be involved throughout design and construction phases of roof and overburden systems. Overburden layout should address access for installation and both roof and overburden maintenance throughout the component service lives.

Inadequate detailing or termination heights leave the roof assembly vulnerable to leaks. Improperly detailed or flashed components may be water-tight for a period of time, but will most likely fail prematurely. Removal of the overburden system for repairs can be an added difficulty and cost. It is good practice to allow penetrations, flashings, expansion joints, drains, and other critical roofing interfaces to be accessible for maintenance and repairs. Flashings should be installed in accordance with current NRCA guidelines and the roof manufacturer's construction details. Ballasted assemblies can block or inhibit drainage resulting in trapped water on the roof membrane. The overburden layout should leave portions of the roof around drains open for both access and drainage and be unimpeded by the overburden.

Summary

While the roof is the primary defense to prevent water entering into a building, due to the current market trends and legislation, this previously underutilized asset is being recognized by owners for the opportunity the roof offers. There are many overburden options and roof assembly considerations when meeting sustainability goals. Once the overburden type is selected, the roof needs to be determined, which depends on the type of overburden and the ultimate use of the roof space. The overburden's success depends on the roof assembly beneath. For installations such as solar or vegetation, the plants and solar array will need to be removed for repairs or replacement; so, a more robust membrane for the long-term durability and serviceability of the complete roof may be needed. A performance-based approach for energy efficiency requirements (insulation, thermal bridges, and air tightness) versus a prescriptive code minimum may be warranted to ensure a long-lasting roof and to minimize roof replacements over the life of the building.

^*Resource: Roofing Contractors Associoation of British Columbia

About the Author

Kristin Westover

Kristin Westover, P.E., LEED AP O+M, is a Technical Manager of Specialty Installations for low-slope commercial roofing systems at GAF. She specializes in cold storage roofing assemblies where she provides insight, education, and best practices as it relates to cold storage roofing. Kristin is part of the Building and Roofing Science Team where she works with designers on all types of low-slope roofing projects to review project design considerations so designers can make informed roof assembly decisions.

As part of its effort to build resilient communities, GAF provides students across the country with opportunities to gain work experience and hands-on training. The GAF co-op program offers participants autonomy and leadership in project management, engineering design, budgeting, project installation, and more.Over the years, the GAF co-op recruiting program has helped students advance academically, grow professionally, and earn competitively while working full time with North America's largest roofing and waterproofing manufacturer.How the GAF Co-Op Program WorksThe program gives students high-impact, hands-on experience in the manufacturing sector. They perform meaningful work alongside supportive GAF mentors and senior leadership while earning a competitive wage. Participants can also receive credits from their university, which they can apply to their coursework.Differences between a Co-op and an InternshipInternships and co-ops have a few notable differences. At GAF, the main difference is the length of time. Internships at GAF usually last 10 weeks, but the co-op program is six months. While internship programs often allow students to stay enrolled in school and complete coursework as they gain professional training, co-op participants must take a semester off to gain full-time work experience.Not all companies pay internship participants for their work. However, at GAF, both interns and co-op students are paid competitive hourly wages. GAF also offers financial relocation assistance for qualifying co-op program candidates.Finally, participants in the GAF programs are there to learn real skills that will help them advance their future careers. GAF interns and co-op students are given the same responsibilities, and chances to collaborate on major projects, as full-time employees.Recent GAF Co-Op Success StoriesMin U, a mechanical engineering student at the University of Maryland, says he "fell in love with manufacturing" thanks to his placement on an engineering project. The experience gave him a firsthand account of the role engineering plays in manufacturing safety, profit, and operations. This ultimately led him to shift his career goals from construction management to manufacturing engineering.When Dante Stellar, an industrial engineering student at Virginia Tech, met GAF representatives at a career fair, he says he didn't expect to become a self-proclaimed "nerd for shingles" and develop a passion for manufacturing. However, that's exactly what happened. And that newfound passion paid off when Dante won Student of the Year from Virginia Tech's Cooperative Education and Internship Program. Dante notes he's now eager to return to GAF and aspires to become a manufacturing leader in the world of shingles.Michael Hesseltine, an electrical engineering student at Texas A&M University, chanced upon a GAF co-op recruiting listing online. After a series of interviews, he landed a project engineering co-op in Ennis, Texas. Working with the Ennis team on major projects solidified his manufacturing engineer career goals.Co-Op Students Complete Meaningful WorkStudents in the GAF co-op program are involved in meaningful projects and get to see their work's impact on day-to-day operations.During his time in Ennis, Michael designed a baler that compacts fiberglass scrap, reducing site disposal trips and costs. He also oversaw renovations of the site's maintenance mechanical break room from start to finish. He notes that his favorite contribution was helping design the electrical system for a dewatering press.In Baltimore, Min's core project was ensuring site compliance with state regulations for discharging stormwater runoff. Min managed all the project contractors and budget with his manager's and mentor's support. Throughout his time there, Min was exposed to Lean methodologies, 5S, risk mitigation, insurance compliance, cost control, and procedure standardization. He gained an overall understanding of manufacturing equipment and business.At the Tampa plant, Dante worked on a rock pad storage expansion project and installed a starwheel machine guarding the manufacturing line, among other important projects. According to Dante, the defining moment of his co-op experience was his granule silo refurbishment project, which involved replacing eight silos, including floor plates and support beams.Dante explains the trust and opportunities his mentors provided were key to his success. "At GAF, I was given the chance to interact with contractors, and immerse myself in the plant, which accelerated my learning," he says.Co-Op Students Build Professional RelationshipsThrough "lunch and learn" sessions, leadership speaker series, meetings with senior leadership, and mentorship, co-op students build long-term professional relationships.Dante was given the chance to showcase the coordination and safety efforts involved in his granule silo project to the GAF executive leadership team in Parsippany, New Jersey.For Min, getting the right feedback to grow meant having the right relationships. He notes the mentorship from his manager Alex Smith and engineering manager Mike Kloda was key to his progression. As advice to future co-op participants, he explains that "everyone is here to help... but it's up to you to drive that forward."Meanwhile, the autonomy and leadership opportunities program leaders gave Michael allowed him to grow technically and professionally. "I was often the go-to person for projects, managing contractors and ensuring everything was on track," he says.Joining an Industry Filled with OpportunityThe GAF co-op program helped Min, Michael, and Dante start and solidify their careers in manufacturing engineering. Following their experience, each student was excited and motivated by the autonomy, responsibility, and growth opportunities they were given. In fact, Min has since accepted a full-time role as a project engineer at the GAF plant in Baltimore. His expected start date is July 7, 2025.GAF is committed to fostering diversity, equity, and inclusion throughout the organization. It believes a talented and diverse organization can drive innovation, growth, and transformation more effectively. To further bolster inclusivity, GAF offers academic and merit scholarships, partners with the Thurgood Marshall College Fund to recruit from the nation's most diverse talent at Historically Black Colleges and Universities and Predominantly Black Institutions, and reaches out to candidates at career fairs nationwide.Bright and motivated minds who want to explore manufacturing have plenty of opportunities. From shingles to solar to environmental impact, GAF offers many exciting career paths.Are you ready to do work that matters and be empowered to explore a leadership role? Discover the co-ops, internships, and job opportunities available at GAF.

Have you ever thought about building products reducing the carbon dioxide emissions caused by your building? When considered over their useful life, materials like insulation decrease total carbon emissions thanks to their performance benefits. Read on for an explanation of how this can work in your designs.What is Total Carbon?Total carbon captures the idea that the carbon impacts of buildings should be considered holistically across the building's entire life span and sometimes beyond. (In this context, "carbon" is shorthand for carbon dioxide (CO2) emissions.) Put simply, total carbon is calculated by adding a building's embodied carbon to its operational carbon.Total Carbon = Embodied Carbon + Operational CarbonWhat is Embodied Carbon?Embodied carbon is comprised of CO2 emissions from everything other than the operations phase of the building. This includes raw material supply, manufacturing, construction/installation, maintenance and repair, deconstruction/demolition, waste processing/disposal of building materials, and transport between each stage and the next. These embodied carbon phases are indicated by the gray CO2 clouds over the different sections of the life cycle in the image below.We often focus on "cradle-to-gate" embodied carbon because this is the simplest to calculate. "Cradle-to-gate" is the sum of carbon emissions from the energy consumed directly or indirectly to produce the construction materials used in a building. The "cradle to gate" approach neglects the remainder of the embodied carbon captured in the broader "cradle to grave" assessment, a more comprehensive view of a building's embodied carbon footprint.What is Operational Carbon?Operational carbon, on the other hand, is generated by energy used during a building's occupancy stage, by heating, cooling, and lighting systems; equipment and appliances; and other critical functions. This is the red CO2 cloud in the life-cycle graphic. It is larger than the gray CO2 clouds because, in most buildings, operational carbon is the largest contributor to total carbon.What is Carbon Dioxide Equivalent (CO2e)?Often, you will see the term CO2e used. According to the US Environmental Protection Agency (EPA), "CO2e is simply the combination of the pollutants that contribute to climate change adjusted using their global warming potential." In other words, it is a way to translate the effect of pollutants (e.g. methane, nitrous oxide) into the equivalent volume of CO2 that would have the same effect on the atmosphere.Today and the FutureToday, carbon from building operations (72%) is a much larger challenge than that from construction materials' embodied carbon (28%) (Architecture 2030, 2019). Projections into 2050 anticipate the operations/embodied carbon split will be closer to 50/50, but this hinges on building designs and renovations between now and 2050 making progress on improving building operations.Why Insulation?Insulation, and specifically continuous insulation on low-slope roofs, is especially relevant to the carbon discussion because, according to the Embodied Carbon 101: Envelope presentation by the Boston Society for Architecture: Insulation occupies the unique position at the intersection of embodied and operational carbon emissions for a building. Insulation is the only building material that directly offsets operational emissions. It can be said to pay back its embodied carbon debt with avoided emissions during the building's lifetime.A Thought Experiment on Reducing Total CarbonTo make progress on reducing the total carbon impact of buildings, it is best to start with the largest piece of today's pie, operational carbon. Within the range of choices made during building design and construction, not all selections have the same effect on operational carbon.When making decisions about carbon and energy reduction strategies, think about the problem as an "investment" rather than a "discretionary expense." Discretionary expenses are easier to reduce or eliminate by simply consuming less. In the example below, imagine you are flying to visit your client's building. Consider this a "discretionary expense." The input on the far left is a given number of kilograms of carbon dioxide equivalent (CO2e) generated for the flight, from the manufacturing of the airplane, to the fuel it burns, to its maintenance. The output is the flight itself, which creates CO2 emissions, but no durable good. In this case, the only CO2 reduction strategy you can make is to make fewer or shorter flights, perhaps by consolidating visits, employing a local designer of record, or visiting the building virtually whenever possible. Now consider the wallpaper you might specify for your client's building. It involves a discretionary expenditure of CO2e, in this case, used to produce a durable good. However, this durable good is a product without use-phase benefits. In other words, it cannot help to save energy during the operational phase of the building. It has other aesthetic and durability benefits, but no operational benefits to offset the CO2 emissions generated to create it. Your choices here are expanded over the previous example of an airplane flight. You can limit CO2 by choosing a product with a long useful life. You can also apply the three Rs: reduce the quantity of new product used, reuse existing material when possible, and recycle product scraps at installation and the rest at the end of its lifespan. In the final step in our thought experiment, consider the insulation in your client's building. As before, we must generate a certain amount of CO2e to create a durable good. In this case, it's one with use-phase benefits. Insulation can reduce operational energy by reducing heat flow through the building enclosure, reducing the need to burn fuel or use electricity to heat and cool the building. The good news is that, in addition to the other strategies considered for the flight and the wallpaper, here you can also maximize operational carbon savings to offset the initial embodied carbon input. And, unlike the discretionary nature of some flights and the often optional decision to use furnishings like wallpaper, heating and cooling are necessary for the functioning of almost all occupied buildings.Based on this example, you can consider building products with operational benefits, like insulation, as an "investment." It is appropriate to look at improving the building enclosure and understanding what the return on the investment is from a carbon perspective. As the comparison above demonstrates, if you have a limited supply of carbon to "invest", putting it into more roof insulation is a very smart move compared to "spending" it on a discretionary flight or on a product without use-phase carbon benefits, such as wallpaper.This means we should be careful not to measure products like insulation that save CO2e in the building use-phase savings only by their embodied carbon use, but by their total carbon profile. So, how do we calculate this?Putting It to the TestWe were curious to know just how much operational carbon roof insulation could save relative to the initial investment of embodied carbon required to include it in a building. To understand this, we modeled the US Department of Energy's (DOE) Standalone Retail Prototype Building located in Climate Zone 4A to comply with ASHRAE 90.1-2019 energy requirements. We took the insulation product's embodied energy and carbon data from the Polyisocyanurate Insulation Manufacturers Association's (PIMA) industry-wide environmental product declaration (EPD).To significantly reduce operational carbon, the largest carbon challenge facing buildings today, the returns on the investment of our building design strategies need to be consistent over time. This is where passive design strategies like building enclosure improvements really shine. They have much longer service lives than, for example, finish materials, leading to sustained returns.Specifically, we looked here at how our example building's roof insulation impacted both embodied and operational carbon and energy use. To do this, we calculated the cumulative carbon savings over the 75-year life of our model building. In our example, we assumed R-30 insulation installed at the outset, increased every 20 years by R-10, when the roof membrane is periodically replaced.In our analysis, the embodied CO2e associated with installing R-30 (shown by the brown curve in years -1 to 1), the embodied carbon of the additional R-10 of insulation added every 20 years (too small to show up in the graph), and the embodied carbon represented by end-of-life disposal (also too small to show up) are all taken into account. About five months after the building becomes operational, the embodied carbon investment of the roof insulation is dwarfed by the operational savings it provides. The initial and supplemental roof insulation ultimately saves a net of 705 metric tons of carbon over the life of the building.If you want to see more examples like the one above, check out PIMA's study, conducted by the consulting firm ICF. The research group looked at several DOE building prototypes across a range of climate zones, calculating how much carbon, energy, and money can be saved when roof insulation is upgraded from an existing baseline to current code compliance. Their results can be found here. Justin Koscher of PIMA also highlighted these savings, conveniently sorted by climate zone and building type, here.Support for Carbon Investment DecisionsSo how can you make sure you address both operational and embodied carbon when making "carbon investment" decisions? We've prepared a handy chart to help.First, when looking at lower-embodied-carbon substitutions for higher-embodied-carbon building materials or systems (moving from the upper-left red quadrant to the lower-left yellow quadrant in the chart), ensure that the alternatives you are considering have equivalent performance attributes in terms of resilience and longevity. If an alternative material or system has lower initial embodied carbon, but doesn't perform as well or last as long as the specified product, then it may not be a good carbon investment. Another consideration here is whether or not the embodied carbon of the alternative is released as emissions (i.e. as part of its raw material supply or manufacturing, or "cradle to gate" stages), or if it remains in the product throughout its useful life. In other words, can the alternative item be considered a carbon sink? If so, using it may be a good strategy.Next, determine if the alternative product or system can provide operational carbon savings, even if it has high embodied energy (upper-right yellow quadrant). If the alternative has positive operational carbon impacts over a long period, don't sacrifice operational carbon savings for the sake of avoiding an initial embodied product carbon investment when justified for strategic reasons.Last, if a product has high operational carbon savings and relatively low embodied carbon (lower-right green quadrant), include more of this product in your designs. The polyiso roof insulation in our example above fits into this category. You can utilize these carbon savings to offset the carbon use in other areas of the design, like aesthetic finishes, where the decision to use the product may be discretionary but desired.When designing buildings, we need to consider the whole picture, looking at building products' embodied carbon as a potential investment yielding improved operational and performance outcomes. Our design choices and product selection can have a significant impact on total carbon targets for the buildings we envision, build, and operate.Click these links to learn more about GAF's and Siplast's insulation solutions. Please also visit our design professional and architect resources page for guide specifications, details, innovative green building materials, continuing education, and expert guidance.We presented the findings in this blog in a presentation called "Carbon and Energy Impacts of Roof Insulation: The Whole[-Life] Story" given at the BEST6 Conference on March 19, 2024 in Austin, Texas.References:Architecture 2030. (2019). New Buildings: Embodied Carbon. https://web.archive.org/web/20190801031738/https://architecture2030.org/new-buildings-embodied/ Carbon Leadership Forum. (2023, April 2). 1 - Embodied Carbon 101. https://carbonleadershipforum.org/embodied-carbon-101/

At GAF, we're serious about our sustainability promise: to protect what matters most, including our people, our communities, and our planet. We recently published 21 new GAF product-specific Environmental Product Declarations (EPDs) as one way we're delivering on that promise.EPDs are critical to improving green building solutions. These standardized and third-party-verified documents outline the environmental impacts associated with a building product's life cycle—from raw material extraction to end-of-life disposal or reuse. Through the EPD creation process, we have been advancing on our sustainability goals, demonstrating our commitment to the environment and our customers, and increasing product sustainability in the roofing industry.Here's a look at our most recent progress and what's expected to come.GAF Sustainability GoalsThe 21 new EPDs are an exciting milestone toward our GAF 2030 Planet Goals, which have four focus areas: increase product transparency, reduce carbon emissions, drive circularity in the roofing sector, and divert operational waste. By 2030, we plan to publish EPDs for our entire commercial and residential core product portfolio. As we've scaled the GAF EPD creation process, through extensive life cycle assessments across our portfolio, we better understand the environmental impact of each stage in our products' life cycles. This opens up internal and external sustainability opportunities as we learn from, and analyze, our life cycle assessment results.Evolving to Product-Specific Environmental Product DeclarationsRoofing has long relied on industry-wide EPDs created from aggregate product data. As a result, our architecture, engineering, and construction (AEC) community members have had fewer opportunities to make informed sustainability choices around roofing materials.According to several sources, the built environment accounts for 39% of global energy-related carbon emissions worldwide. Collectively, we as a roofing industry could help reduce this number by increasing our transparency documentation. With more product-specific Environmental Product Declarations, companies and customers can make more informed product sustainability decisions.And although GAF currently has the highest overall number of transparency documents for roofing materials in the industry, we know we also have an opportunity to grow.GAF Uses Life Cycle Assessments to ImproveWe review product Life Cycle Assessments (LCAs) to understand the environmental impact of each product's production stages, from raw material extraction to end-of-life. Then, we can use that information to identify areas of improvement and make informed decisions to reduce a product's environmental impact, resulting in a reduction in embodied carbon. The knowledge we gain from our LCAs creates the potential for product improvements and new innovations to help further our 2030 Planet Goals.Looking Toward 2030 and BeyondWe're working hard to continue leading the industry with transparency documentation such as EPDs, Health Product Declarations, and Declare Labels. But we're not stopping there.We're fostering collaboration in our broader building, construction, and design space to help reduce the built environment's total carbon emissions. At GAF, sustainability isn't checking a box. We believe in and champion protecting our homes and our planet. By changing how we do business, we hope to improve how builders can build and, ultimately, how our world lives.Empowering the AEC CommunityTransparency and product sustainability documentation help us all build a better world. We're committed to empowering designers, builders, architects, and engineers by providing information about the lifecycle and environmental impact of GAF products whenever possible.Explore some of our most recent EPDs below.Polyiso InsulationEnergyGuard™ Barrier. Polyiso InsulationEnergyGuard™ HD and HD Barrier Polyiso Cover BoardEnergyGuard™ HD Plus Polyiso Cover BoardEnergyGuard™ NH Barrier Polyiso InsulationEnergyGuard™ NH HD Plus Polyiso Cover BoardEnergyGuard™ NH HD Polyiso Cover BoardEnergyGuard™ NH Polyiso InsulationEnergyGuard™ NH Ultra Polyiso InsulationEnergyGuard™ NH Ultra Tapered Polyiso InsulationEnergyGuard™ Polyiso InsulationEnergyGuard™ Ultra Polyiso InsulationUltra HD Composite InsulationTPO Single-Ply MembraneEverGuard® TPO Extreme Fleece-backEverGuard® TPO ExtremeEverGuard® TPOEverGuard® TPO Fleece-backEverGuard® SA TPO Self-Adhered Roof MembranePVCEverGuard® PVCEverGuard® PVC Fleece-back Roof CoatingsHydroStop® System GAF Acrylic Top CoatLooking to explore more sustainable design solutions? You can learn how GAF is investing in our people, our planet, and progress for a more sustainable future, here.

Don't miss another GAF RoofViews post!

Subscribe now