RoofViews

Science du bâtiment

Conception avec polyiso

17 mars 2021

Thermal insulation is an important part of commercial roofing assemblies. As with anything, there are ways to design with and install polyiso insulation — a better way, a best way, and many variations in-between! Ce qui peut être le mieux pour réduire les coûts initiaux peut s'avérer seulement bon ou très mauvais sur la durée de vie à long terme du bâtiment.

As discussed later, important points to remember about polyiso and its use include:

Due to polyiso's very low air permeability, good design and installation practices can result in low risks of condensation, even for buildings with somewhat higher than normal humidity levels.
Building designers can use the label R-value, stated at a mean temperature of 75°F, for projects in most ASHRAE climate zones. However, for climate zones 6 and 7, it may be appropriate to use published values at 40°F.
Electricity is four times as expensive as gas, on an equivalent Btu basis. Therefore, polyiso's greatest value is seen during summer months when air conditioning usage is at its highest.

Introduction

Polyiso has become the go-to insulation for commercial roofing with about 75 % market share. The reasons include:

Lowest cost per R-value.
High R-value per inch, meaning it doesn't require as much thickness as other types of rigid insulation to achieve the same insulation performance.
Good fire resistance. Being a thermoset unlike polystyrene foams, it doesn't melt during a fire. Melting of thermoplastic foams and subsequent flowing down of molten material through the deck into a building can be hazardous for occupants and fire crews.
Solvent compatibility - adhesives used in adhered systems don't adversely affect polyiso. This is not the case with polystyrene foams.
Reduced condensation — When installed correctly in a properly designed system, polyiso helps to resist interior air from reaching the underside of the membrane, thereby reducing condensation risks.

However, just because polyiso is specified and used doesn't mean that the ideal outcome is reached. There are installation details that need to be considered.

Single-ply membrane combined with polyiso can make for a good roof, but additional factors can improve performance:

The Basics

Polyiso boards have straight cut edges (the boards are not tongue and grooved). These butt joints between boards can allow for vertical air movement.

Polyiso was often installed as a single layer:

As shown in the figure above, a single layer of butt-jointed insulation is generally a bad idea and is no longer allowed by the International Building Code (IBC) in the 2018 and newer versions. For roofs with a single layer of butt-jointed insulation boards:

There is little restriction for air flow and so, during wind events, wind uplift forces result in membrane billowing for attached systems.
Membrane billowing draws interior conditioned air up to the underside of the membrane and may create a risk of condensation within the assembly.
Billowing may place additional stress on membrane fasteners, a factor recognized by membrane manufacturers by the issuance of shorter guarantees or warranties for mechanically attached versus adhered membrane.
Essentially unrestricted air flow up into the assembly diminishes the insulation value and lowers energy efficiency.

In contrast, two layers of polyiso restrict the free flow of air into the roof assembly. Care must be taken to seal between roof penetrations and the polyiso, or air is still free to move up into the assembly as shown here:

Spray foam is a good choice for achieving a seal between the polyiso and the penetrations.

Two layers of polyiso with staggered joints and sealed penetrations is a good system, but two of its features still reduce its insulation efficacy. These are shown in the following magnified view of a roof assembly cross-section.

This cross-section illustrates lower energy efficiency resulting from:

Insulation and membrane fasteners both act as thermal bridges, conducting heat through the assembly.
Gaps between insulation boards that allow thermal convection to occur
When both the insulation and membrane are attached and fastener densities are at their highest, R-value reductions of up to 29 % have been predicted.

Adhered versus Attached

The alternative to mechanical attachment is to adhere the insulation with adhesive. Typically, low rise foam is the adhesive used for both insulation and cover board installation. The original method of application was as a ribbon but for labor savings it is often sprayed in a spatter-pattern as shown in the following picture of a typical installation in progress using one of GAF's low rise foams

Usually, when polyiso is adhered, the roof membrane is also adhered. For a steel deck substrate, fasteners are typically only used for the first layer of insulation, and then the adhesive is used on the subsequent layers of insulation and membrane. While it may be possible to adhere directly to a steel deck and eliminate fasteners totally, this approach is more common with concrete decks, as shown in the schematic here:

Key features of systems with adhered insulation are:

Air flow up through the assembly is limited and the risk of condensation in cold climates is low. Similarly, membrane billowing is minimized due to the restricted air flow up through adhered insulation layers.
Thermal bridging is minimized since only the first layer of insulation might be mechanically attached. With concrete decks, the first layer of polyiso can be adhered thereby eliminating the use of fasteners totally.
Wind uplift resistance is uniformly distributed across the roof deck. A system with adhered membrane and insulation can act as a monolithic system with excellent wind uplift resistance.
When combined with an adhered membrane the finished roof appearance is usually aesthetically pleasing. When applied in accordance with manufacturer's instructions, the membrane can be very flat and there will not be any insulation fasteners to telegraph through and mar the appearance.

Soudés par induction

Induction welded fasteners are another type of roof attachment, the largest type being the Drill-Tec™ RhinoBond® system. By definition this is a mechanical attachment method but it has many of the features of adhered systems. The technique fastens TPO and PVC membranes to the substrate below using a microprocessor controlled induction welding machine. The thermoplastic roof membrane is welded directly to specially coated fastening plates used to attach the insulation. The picture below shows such a system being used:

The induction machine is placed above each plate in turn and activated for approximately 10 seconds. As the machine is moved to the next position, a weighted magnet is placed over the plate and acts to squeeze the membrane down onto the hot fastener plate causing it to weld to that plate's surface coating.

For typical mechanical attachment of single-ply membranes with fasteners along the seam lines, the insulation boards are simply secured with five fasteners per 4 x 8 ft. board to keep them flat. When using a Drill-Tec™ RhinoBond® system, the combined insulation and membrane fasteners resist wind uplift forces as shown in this picture during a test of wind uplift resistance:

Thinking outside the seam | Professional Roofing magazine

This means that wind loads are more uniformly distributed versus a conventionally attached system.

Key features of systems with induction welded membrane attachment are:

Performance is very similar to adhered in terms of the distribution of loads.
Thermal bridging is reduced compared to traditional mechanically attached membrane systems.
There are no application temperature restrictions and so this approach can be used in place of adhesive attachment regardless of how cold it might be.
Drill-Tec™ RhinoBond® systems can be cost competitive due to the speed of installation as compared with traditional bucket and roller adhesives.

Dew Point Calculations

The dew point is the temperature at which moisture vapor forms condensation. It's a function of the relative humidity and the ambient temperature. The evaluation of a roof assembly where the dew point might be reached is an important step towards designing a roof with minimized condensation risks. The topic has been covered in greater depth elsewhere, but this section summarizes the key steps. Examine the chart below (this is a simplified form of what is used by HVAC engineers).

Locating 40 % relative humidity in the first column and then going across to the 70°F, design dry bulb temperature shows a dew point of 45°F. This means that in an environment that is 70°F and 40 % relative humidity (RH), water in the air will condense at a temperature of 45°F. A roof assembly separates the interior conditioned environment from the outside and the insulation layer in the roofing system resists heat loss or gain to/from the outside, depending on the season. Within the insulation layer the temperature has a gradient between the hot and cold side, i.e. between inside and outside.

As an example, consider a building in the winter to illustrate the point. The interior is 70 °F with 40 % RH, like the example on the chart above. The temperature gradually drops from the innermost part of the insulation until at the outermost part it will be at the exterior, cold temperature. The plotting of temperature through the insulation thickness is referred to as the temperature gradient of that system. Using the example, if the temperature gets to the dew point of 45°F at any point in that system then water would be expected to condense on the nearest surface. This is shown in the following diagram:

Summarizing, in this example the interior air has 40 % of the total water vapor that it can support. But as the air migrates up through the roof system, it gets cooler until the point where it can no longer hold onto the water vapor and condensation occurs. In the example shown above, that's at 45°F and just inside the insulation layer.

As will be discussed later, dew point calculations can be used to inform the placement of a vapor retarder layer when used.
When a dedicated vapor retarder layer is not used, it is good practice to ensure that the dew point is in the upper layer of polyiso insulation. This will lower the risk of interior air migrating up through the roof assembly and condensing on a surface below its dew point.

Using Vapor Retarders with Polyiso

Vapor retarders can be used to limit humidity ingress to the roof assembly. Under certain circumstances, depending on the building use and location, condensation can occur as discussed in the previous dew point discussion. In general there are four basic building conditions that can be considered:

1. Buildings with Standard Amounts of Occupancy-Generated Moisture

These are the most common situations covering for example, office, retail, and warehouse spaces. The risk of having a condensation issue is low and good roofing practices such as sealing around penetrations may likely suffice.

2. Buildings with Larger Amounts of Occupancy-Generated Moisture

This category includes apartments and other multiple residency buildings, paper mills, laundries, buildings with indoor swimming pools, and the like. In fact, anything that doesn't fit into category 1 above should be evaluated to determine humidity levels. The building's air handling and ventilation systems should be carefully specified to take into account the moisture loading.

3. Construction–Related Moisture

Most construction practices release some amount of moisture into the building space. These can be relatively short term such as drywall installation and painting. However, some practices can release large amounts of water over a considerable time frame into the building. These include poured in place concrete floors and roof decks.

4. Concrete Roof Decks

These can present a challenge for roof system designers especially in new construction. Regardless of the type of concrete, significant amounts of water remain after curing is completed. Allowing concrete to thoroughly dry is most appropriate; however, it is often reasonably impractical. Dealing with potential moisture in concrete decks is beyond the scope of this article, but guidance can be found elsewhere.

It is recommended that a building science professional experienced in designs for Categories 2, 3, and 4 be involved to determine whether a vapor retarder should be used and what type.

Specification of R-Value

Polyiso is manufactured to meet the ASTM C1289 Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board. ASTM C1289 specifies the thermal resistance at a mean temperature of 75°F for various product thicknesses and requires that the values at 40 and 110°F be made available upon request.

Important features of manufacturer's published R-values are:

The values are an average across a temperature range. The test methods need the insulation specimen to have a hot and a cold side at least 40°F apart. Most reputable test labs use a difference of 50°F for accuracy. A published value at 75°F is actually an average R-value across the range of 50 to 100°F.
To take into account the diffusion of gas out of, and air into the polyiso foam, the values are based on projected "Long Term Thermal Resistance" or LTTR, obtained by rapidly aging thin slices of the foam.
The Polyisocyanurate Insulation Manufacturers Association, PIMA, conducts a third-party certification program to independently validate LTTR values. This is referred to as the PIMA QualityMark™ program. The LTTR values are considered as "labelled R-values" to be used by building design professionals.
Label R-values represent a 15-year time-weighted average value. They can help a design professional estimate a building's energy efficiency without having to be concerned about long-term loss of performance, which is already factored into the value.
Building design professionals designing roofs for ASHRAE climate zones 6 and 7 may need to use the R-value reported for a mean temperature of 40°F.

Attachment Patterns

The various fastener patterns for polyiso have been mentioned in the previous sections. However, due to the impact of fasteners on thermal bridging and wind uplift resistance, the key points are summarized here:

For systems that have both mechanically attached membrane and insulation, the membrane attachment provides the wind uplift resistance. The polyiso insulation fasteners are simply there to hold the insulation flat during the roof installation and to resist long term lateral movement.
Typical fastener patterns are shown here:

For systems with adhered single-ply membrane and mechanically attached polyiso boards, the insulation fasteners provide the wind uplift load resistance. This is the case whether both layers of polyiso are mechanically attached or only the bottom layer (in which case the upper layer would be adhered).
Manufacturers have tested the fasteners per board required to meet wind uplift resistance requirements for these combined mechanically attached and adhered systems. The number of fasteners needed depends on the board size and thickness. For common systems, the numbers are shown in the table below:

For each of these combinations above, manufacturers' handbooks provide fastener patterns.
The number of fasteners for these combined mechanically attached and adhered systems is very large, for example a 125 000 s.f. big box type roof could require around 50 000 fasteners, resulting in significant thermal bridging.
When installing over a steel deck, to reduce thermal bridging and to make for a more robust system with reduced condensation risk, it is advisable to only attach the first layer of polyiso and to adhere all subsequent layers and the membrane.
If the first layer of polyiso is attached and the rest of the system adhered, then using a 1,5" thickness for that first layer would help to bury the thermal bridging fasteners. It could also put the dividing line between first and second polyiso layers below the dew point, which is advisable.

Pour conclure

Polyiso is a cost-effective roof insulation and has the advantage that its permeability is low. Good design and installation practices can result in low risks of condensation even for buildings with higher than normal humidity levels.
When designed correctly, mechanically attached components with two layers of polyiso having staggered and offset joints can be part of a successful roof system.
Adhered insulation and membrane roof systems have advantages including reduced or eliminated thermal bridging, lowered condensation risks, and better wind uplift resistance.
In cases where building use anticipates higher interior humidity levels and/or the local climate suggests higher condensation risk, then a building science professional should be consulted as to vapor retarder use and specification.
Building designers and specifiers are advised to use the labelled R-values shown for a mean temperature of 75°F. For projects in ASHRAE climate zones 5 and 6, values at 40°F could be used depending on the building's geometry and local energy costs.

About the Author

Thomas J Taylor

Thomas J Taylor, Ph. D. est le conseiller scientifique de la science de la construction et de la toiture de GAF. Tom compte plus de 20 ans d'expérience dans l'industrie des produits de construction à travailler pour des entreprises manufacturières. Il a obtenu son doctorat en chimie à l'University of Salford, en Angleterre, et détient environ 35 brevets. Chez GAF, Tom se consacre principalement à la conception de systèmes de toiture et à la réduction de la consommation d'énergie des bâtiments. Sous la direction de Tom, GAF a développé un TPO avec une résistance aux intempéries inégalée.

Les chaleurs extrêmes ont été la principale cause de décès liés aux conditions météorologiques aux États-Unis au cours des 30 dernières années. En effet, entre 2010 et 2020, environ 12 000 américains sont morts de chaleur extrême, les communautés amérindiennes et noires étant touchées de manière disproportionnée. Around the globe, excess heat collects in urban areas and can contribute to increased heat-related death and illness, diminished quality of life, and reduced economic opportunities.One example of this urban heat is Los Angeles's Pacoima neighborhood. During days of extreme temperatures, Pacoima had seven times the number of excess heat emergency room visits (19 000 between 2009 and 2018) compared with nearby Santa Monica, an affluent community of similar size, according to Bloomberg.Economic sectors, such as tourism and local businesses, also feel the effects of urban heat. Pacoima food truck vendor Jennifer Ramirez told Bloomberg she couldn't start work until outdoor and street temperatures cooled. Otherwise, her food truck generator could blow out.Fortunately, cooling strategies are now available and being used in initiatives like the GAF Cool Community Project to help mitigate urban heat.Understanding Heat IslandsYou can envision heat islands as heat-saturated sponges spread out across vast, shimmering urban spaces. These "islands" tend to have minimal shady vegetation, so their blacktop and hard surfaces-such as pavements, parking lots, concrete recreation areas, and roofs-absorb and retain the sun's heat well into the evening. Temperatures in urban heat islands can often be 15°F to 20°F hotter than in equivalent vegetated areas.In technical terms, darker, tarmac-covered surfaces have a "low albedo" effect, which describes the ability to reflect and diffuse the sun's rays back to the upper atmosphere. Meanwhile, reflective, snow-covered regions such as the Arctic have "high albedo." Areas with low albedo are at greater risk of experiencing increased heat retention.Densely packed buildings compound a low albedo effect by preventing cooling breezes from lowering temperatures. To top it off, heat islands can trap waste heat from cars, air conditioners, and other heat-emitting devices-exacerbating the effects. In terms of detrimental environmental impacts, this is the perfect, overheated, storm.Shifting from Heat Islands to Cool CommunitiesThe GAF Cool Community Project addresses the complex issue of urban heat with a simple solution: Take a hot, sun-exposed community with an abundance of heat-retaining surfaces. Then, apply colorful, solar-reflective coating to its streets and public hardscaping-such as GAF StreetBond® pavement coatings with Invisible Shade™, which Time magazine named one of the Best Inventions of 2022.The result? Cooler surfaces and ambient air temperatures.Making Progress on Cooling PacoimaLA's Pacoima neighborhood is one example of a community hit hard by heat. A true urban heat island, it has consistently been one of the city's hottest areas. On one summer afternoon in 2022, Bloomberg reported a pavement temperature of 127°F at noon. Just one hour later, it had risen to 141,8°F.Many of Pacoima's residents are in lower-income brackets and live in spaces that haven't been fully optimized to mitigate heat island effects. So, combatting the heat became a priority for local officials and organizations. Melanie Torres, community organizer with Pacoima Beautiful, said that "the cooling solutions that were brought here to Pacoima were actually very impactful to our community." Torres shared, "it definitely cooled things down, but we definitely did need the educational aspect -beginning the discussion of climate exchange and what extreme heat is, and how we can create solutions to combat it."With resources and support from GAF and non-profit partners, more than 700 000 square feet worth of streets, parking lots, and other hardscapes were coated with StreetBond® over a contiguous 10-block area. Attractive, colorful solar-reflective materials cover the park and playground areas, and blue and white coatings brighten the public basketball court. The formerly dark streets are now a cool gray-blue.According to Miguel Angel Luna, president of Urban Semillas, Pacoima residents are right "on the front line of climate change." Urban Semillas is an LA-based social and environmental justice consultancy working with GAF on the Cool Community Project.Achieving Positive Results in PacoimaOver the past year, Cool Community Project members monitored pavement and air temperatures using sensors, satellite technology, and drones. Findings from the past 12 months of observation have shown a positive impact on the Pacoima community:Ambient air temperature (Surface temperatures have been reduced by an average of 10°F during the daytime on sunny days.The second phase of the project includes applying pavement coatings to an additional 500 000 square feet of streets and introducing a new cooling technology on select residences-Timberline® CS Shingles. These shingles are made with a highly reflective material that can help reduce attic temperatures and air conditioning costs.In addition to heat reduction and urban beautification, GAF StreetBond® can help preserve pavement. Longer-lasting pavement can save cities time, money, and resources while giving them another tool to help mitigate the impacts of climate change. This is just another way GAF is looking to strengthen communities from the ground up.Through this project, GAF and its partners aim to improve the lives of the roughly 2 000 people living within the project area of Pacoima. They're accomplishing this by taking what Jeff Terry, GAF vice president of sustainability, describes as a "complete community approach," which involves residents and local organizations coming together to create a model for cities around the world.Reducing Temperatures at HomeWhether urban or rural, all communities can use technology to help reduce indoor and outdoor temperatures. Some cooling strategies that can be effective across cities or in your own home include:Cool SurfacesSurfaces treated with solar-reflective coatings can help reduce heat absorption and lower street and ambient air temperatures. Plus, products such as StreetBond® come in a range of colors to highlight urban areas and preserve pavement.Cool RoofsSolar reflective shingles like Timberline® CS Shingles may save homeowners an average of 7 % to 15 % on their total cooling costs.* This cooling technology can minimize a building's solar heat gain by reflecting incoming sun rays and reemitting the absorbed energy.Ready to get started in your neighborhood? Check out the inspiring community improvement projects at streetbond.com. (A division of GAF, StreetBond® offers the same quality and reliability customers have come to rely on from North America's largest roofing and waterproofing manufacturer.)*Potential for savings depends on various factors including, but not limited to, climate zone, utility rates, location, and HVAC equipment efficiency.

Quelle est la chaleur exacte d’un toit en été? Selon le département de l’Énergie des États-Unis, les toits à bardeaux d’asphalte foncés traditionnels peuvent atteindre les 150 °F par une journée d’été. And prolonged exposure to high heat like this can damage your roof.Four Potential Effects of Summer Weather on Your RoofHere are four common ways hot summer weather can adversely affect your roof system:1. High HeatOver time, high heat can damage roofing materials.2. Ultraviolet LightUV light shines down on your roof on both sunny and cloudy days during the summer. Over time it can cause materials to deteriorate and diminish the amount of protection your roof shingles ultimately provide, leaving your roof vulnerable to leaks.3. HumiditySummer's high humidity can also damage your roof by creating condensation that collects under the shingles. If left unaddressed, this moisture can cause water damage, leaks, or mold growth.4. Thermal ShockThermal shock occurs when high temperatures during the day are followed by quickly cooling temperatures at night. This temperature swing can cause roofs to expand and contract rapidly, weakening the roof's integrity.How to Reduce the Risk of Heat Damage to Your RoofHere are a few strategies to help reduce the risk of heat damage:Ventilate the AtticA properly balanced attic ventilation system helps damaging heat and moisture to escape. Make sure you have the proper amount of ventilation needed to keep attic temperatures down.Maintain and Clean ShinglesRegularly removing debris and replacing damaged shingles can help ensure your roofing system is operating correctly. If you don't take care of your roof, its integrity could be compromised. It's best to leave this work to the professionals, so consider scheduling regular maintenance.Have the Roof InspectedHave your roof inspected at least twice a year for damage. Have a professional perform these inspections, as they know what to look for and can do so safely. Damage can often be seen inside your home before it shows up on your roof, so be sure the inspection looks both inside and outside for potential issues.Choose a Cool RoofInstalling a highly reflective roof (often known as a "cool roof") can help prevent early damage from the sun and may even help reduce cooling costs.1 How hot does a roof get in the summer when it's designed with "cooler" materials? A highly reflective roof can keep the surface 50°F cooler compared to traditional roofs, notes the US Department of Energy.2Benefits of Cool RoofsTwo factors affect the coolness of a roof: thermal emittance and solar reflectance. Thermal emittance is a roof's ability to shed heat by giving off thermal infrared radiation. Solar reflectance is its ability to reflect or bounce sunlight off the roof before heat is created.In general, light-colored roofs stay cooler than darker ones. However, new advances have made it possible to get cool roofs in a variety of architecturally pleasing colors. The benefits of a cool roof may include:Lowering cooling costs1Reducing the load on air conditionersEligibility for rebates and other incentives from utilities or government programs4Decreasing roof temperature, which may help extend the life of the roofCurious to learn more? Contact a local roofing professional today to find out how you can reduce the temperature of your roof, either through increased ventilation or by installing a cool roof system.1 Energy cost savings are not guaranteed and the amount of savings may vary based on climate zone, utility rates, radiative properties of roofing products, insulation levels, HVAC equipment efficiency, and other factors.2,3: From energy.gov/energysaver/cool-roofs.4 Rebates and Incentives, and their eligibility requirements vary and availability is not guaranteed.

Les sociétés, les organisations et les cabinets opérant dans le secteur de la conception et de la construction ont une opportunité et une responsabilité uniques. Collectivement, nos émissions de carbone représentent près de 40 % dans le monde. While the goals, commitments, pledges, and promises around these challenges are a step in the right direction, no one entity alone will make major improvements to this daunting issue.We need to come together, demonstrate courageous change leadership, and take collective approaches to address the built environment's impacts on climate. Collectively, we have a unique opportunity to improve people's lives and make positive, measurable changes to impact:Buildings, homes, and hardscapesCommunity planningConsumer, commercial, and public sector behaviorOur Collective Challenge to Reduce our Carbon FootprintAccording to many sources, including the U.S. Green Building Council (USGBC), the built environment accounts for 39 % of global energy-related carbon emissions worldwide. Operational emissions from buildings make up 28 % and the remaining 11 % comes from materials and construction.By definition, embodied carbon is emitted by the manufacture, transport, and installation of construction materials, and operational carbon typically results from heating, cooling, electrical use, and waste disposal of a building. Embodied carbon emissions are set during construction. This 11 % of carbon attributed to the building materials and construction sector is something each company could impact individually based on manufacturing processes and material selection.The more significant 28 % of carbon emissions from the built environment is produced through the daily operations of buildings. This is a dynamic that no company can influence alone. Improving the energy performance of existing and new buildings is a must, as it accounts for between 60-80 % of greenhouse gas emissions from the building and construction sector. Improving energy sources for buildings, and increasing energy efficiency in the buildings' envelope and operating systems are all necessary for future carbon and economic performance.Why It Is Imperative to Reduce our Carbon Emissions TodayThere are numerous collectives that are driving awareness, understanding, and action at the governmental and organizational levels, largely inspired by the Paris Agreement enacted at the United Nations Climate Change Conference of Parties (COP21) in 2015. The Architecture 2030 Challenge was inspired by the Paris Agreement and seeks to reduce climate impacts from carbon in the built environment.Since the enactment of the Paris Agreement and Architecture 2030 Challenge, myopic approaches to addressing carbon have prevailed, including the rampant net-zero carbon goals for individual companies, firms, and building projects. Though these efforts are admirable, many lack real roadmaps to achieve these goals. In light of this, the US Security and Exchange Commission has issued requirements for companies, firms, and others to divulge plans to meet these lofty goals and ultimately report to the government on progress in reaching targets. These individual actions will only take us so far.Additionally, the regulatory environment continues to evolve and drive change. If we consider the legislative activity in Europe, which frequently leads the way for the rest of the world, we can all expect carbon taxes to become the standard. There are currently 15 proposed bills that would implement a price on carbon dioxide emissions. Several states have introduced carbon pricing schemes that cover emissions within their territory, including California, Oregon, Washington, Hawaii, Pennsylvania, and Massachusetts. Currently, these schemes primarily rely on cap and trade programs within the power sector. It is not a matter of if but when carbon taxes will become a reality in the US.Theory of ChangeClimate issues are immediate and immense. Our industry is so interdependent that we can't have one sector delivering amazing results while another is idle. Making changes and improvements requires an effort bigger than any one organization could manage. Working together, we can share resources and ideas in new ways. We can create advantages and efficiencies in shared R&D, supply chain, manufacturing, transportation, design, installation, and more.Collaboration will bring measurable near-term positive change that would enable buildings and homes to become net-positive beacons for their surrounding communities. We can create a network where each building/home has a positive multiplier effect. The network is then compounded by linking to other elements that contribute to a community's overall carbon footprint.Proof of Concept: GAF Cool Community ProjectAn estimated 85 % of Americans, around 280 million people, live in metropolitan areas. As the climate continues to change, many urban areas are experiencing extreme heat or a "heat island effect." Not only is excess heat uncomfortable, but heat islands are public health and economic concerns, especially for vulnerable communities that are often most impacted.Pacoima, a neighborhood in Los Angeles, was selected by a consortium of partners as a key community to develop a first-of-its-kind community-wide research initiative to understand the impacts various cooling solutions have on urban heat and livability. Pacoima is a lower income community in one of the hottest areas in the greater Los Angeles area. The neighborhood represents other communities that are disproportionately impacted by climate change and often underinvested in.Implementation:Phase 1: This included the application of GAF StreetBond® DuraShield cool, solar-reflective pavement coatings on all ground-level hard surfaces, including neighborhood streets, crosswalks, basketball courts, parking lots, and playgrounds. The project also includes a robust community engagement process to support local involvement in the project, measure qualitative and quantitative impact on how cooling improves living conditions, and ensure the success of the project.Phase 2: After 12 months of monitoring and research, GAF and partners will evaluate the impact of the cool pavements with the intent to scale the plan to include reflective roofing and solar solutions.This ongoing project will allow us to evaluate for proof of concept and assess a variety of solutions as well as how different interventions can work together effectively (i.e., increasing tree canopies, greenspacing, cool pavements, cool roofs, etc.). Through community-wide approaches such as this, it's possible that we could get ahead of the legislation and make significant innovative contributions to communities locally, nationally, and globally.GAF Is Taking Action to Create Community-wide Climate SolutionsWith collaboration from leaders across the building space and adjacent sectors, we believe it is possible to drive a priority shift from net neutral to net positive. Addressing both embodied and operational carbon can help build real-world, net-positive communities.We invite all who are able and interested in working together in the following ways:Join a consortium of individuals, organizations, and companies to identify and develop opportunities and solutions for collective action in the built environment. The group will answer questions about how to improve the carbon impacts of the existing and future built environment through scalable, practical, and nimble approaches. Solutions could range from unique design concepts to materials, applications, testing, and measurement so we can operationalize solutions across the built environment.Help to scale the Cool Community project that was started in Pacoima. This can be done by joining in with a collaborative and collective approach to climate adaptation for Phase 2 in Pacoima and other cities around the country where similar work is beginning.Collaborate in designing and building scientific approaches to determine effective carbon avoidance-or reduction-efforts that are scalable to create net-positive carbon communities. Explore efforts to use climate adaptation and community cooling approaches (i.e., design solutions, roofing and pavement solutions, improved building envelope technologies, green spacing, tree coverage, and shading opportunities) to increase albedo of hard surfaces. Improve energy efficiency to existing buildings and homes and ultimately reduce carbon at the community level.To learn more and to engage in any of these efforts, please reach out to us at sustainability@gaf.com.

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