Assessing aluminum’s LCA

by Katie Daniel | August 11, 2017 9:45 am

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by Ben Mitchell and Vikas Ahuja
It is incumbent on designers and specifiers to develop an increasingly sophisticated understanding of how various products and materials impact the environment. General terms such as ‘green’ and ‘sustainable’ are giving way to ISO-guided, science-based, standardized measures of products’ and buildings’ environmental performance. Fortunately, assessment tools and methodologies are making these measures easier to access and understand.

To designers and specifiers, the most familiar of these tools is the Environmental Product Declaration (EPD). Produced by manufacturers, but verified by independent third parties, these provide quantified environmental data. An EPD can be done by an individual manufacturer (known as a ‘product-specific EPD’) or an entire industry (known as an ‘industry-average EPD’). When using the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) system, the maximum credit contribution is via the product-specific EPD route. However, industry-average EPDs can contribute toward LEED Material Resources (MR) credits.

These include Building Product Disclosure and Optimization–
Environmental Product Declarations, which awards one point for using at least 20 different permanently installed products sourced from at least five different manufacturers that have used a form of life cycle analysis (LCA). A building product with a product-specific EPD counts as one whole product, whereas one with an industry-average EPD counts as half a product. A second point contribution can be possible when a manufacturer can demonstrate optimization (i.e. by using an EPD to show impact reduction below an industry average).

Many designers are also familiar with product category 
rules (PCRs), which are foundational to EPDs and set parameters for data collection and reporting, as well as for 
the type of information used in EPDs. PCRs are consensus-based documents developed by stakeholder organizations, defined in ISO 14025, Environmental Labels and Declarations–Type III Environmental Declarations, as “a set of specific 
rules, requirements, and guidelines for developing Type III environmental declarations for one or more product categories.” There must always be a PCR before a manufacturer can produce an EPD.

Life cycle analysis describes the process by which the parameters set forth in PCRs can be used to compile and evaluate inputs, outputs, and the potential environmental impacts of a product, system, or even 
a whole building throughout its life cycle. EPDs contain a summary, or selected results, of an LCA. They communicate information about the life cycle environmental impact of individual products, and can include additional environmental information, as relevant.

To develop an EPD, an LCA practitioner or consultant typically:

• identifies the correct PCR;
• collects inputs and outputs;
• uses software for LCA modeling; and
• creates EPD documentation.

Upstream data from relevant databases supplements data and assists with 
the assessment.

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How LCA affects both design 
and specifications
Incentives for owners and designers to choose environmentally preferable products—and consider LCA results—have increased with the introduction of LEED v4 Building Product Disclosure and Optimization credits. Points are awarded for EPDs, as well as the sourcing of raw materials and ingredients.

Some design professionals believe once an EPD is in hand, adequate information is contained therein and no further research is necessary. However, it is important to become familiar with PCRs and LCAs as well as EPDs, as a means of verifying individual EPDs comply with methodological prerequisites. Care must also be exercised in comparing one manufacturer’s EPD to that of another. The only way two EPDs can be compared is if the PCR is the same, the product function is identical, and the software and underlying data used to do the LCA are the same in both cases.

Conversations about environmental impact center on carbon emissions, or ‘carbon footprint,’ even though this is often just one aspect of environmental impact. Product, system, and building life cycles can touch on a vast number of processes, so it is useful to set system boundaries clarifying just what is included in a given assessment. ISO 14044, Environmental Management–Life Cycle Assessment–Requirements and Guidelines, allows LCA practitioners to consider any boundary, including or excluding any process, as long as that boundary is disclosed.

This makes sense for manufacturers of products that can have a wide variety of applications once they leave the plant gate—hence the nomenclature ‘cradle-to-gate’ for an LCA that does not consider installation and use phases. However, building designers generally need to be concerned with cradle-to-grave LCAs, which include use phase and end-of-life considerations. In this scenario, the impacts of the use phase dominate most other life cycle stages.

The extensive amount of comparisons that need to be made when benchmarking environmental impacts from cradle to grave means useful tools for designers include LCA databases. These can perform whole-building LCAs throughout the design process, in real time. They are populated with industry-average life cycle impacts and product-specific EPDs, making design scenario comparisons fast, flexible, and easy.

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In-depth example: Aluminum building components and LCA
From curtain walls and façade cladding panels to commercial windows, sunscreens, and louvers, aluminum exterior building systems and components are widely used.

For glazed systems, common impact categories will include:

• resource use—renewable and nonrenewable material resources, freshwater consumption, and primary energy demand (i.e. inputs requiring renewable and fossil energy sources);
• global warming potential (GWP)—outputs leading to global warming (expressed as carbon dioxide [CO₂] equivalents in kilograms);
• acidification potential—outputs leading to acid rain/forest decline (expressed as sulfur dioxide equivalents in kilograms);
• eutrophication potential— outputs leading to overfertilization of the soil or water (expressed as nitrogen equivalents in kilograms);
• smog formation potential—outputs with potential photochemical ozone creation (expressed as ozone equivalents in kilograms);
• ozone depletion potential—outputs leading to thinning of the ozone layer in the upper atmosphere (expressed as trichlorofluoromethane equivalents in kilograms); and
• waste—hazardous and nonhazardous waste disposed and materials for recycling.

Aluminum and resource use
Aluminum is the most commonly recycled postconsumer metal in the world. Recent decades have seen a notable increase in the material’s secondary production (the process of recycling aluminum scrap so it can be used again). According to the Aluminum Association, “Nearly 40 percent of the North American aluminum supply is now created through secondary production, up around 10 percent since the early 1990s.” (This information was derived from www.aluminum.org/industries/production/secondary-production[4].) In fact, approximately 65 percent of all the aluminum ever produced is still in use.

Recycled aluminum consumes only about five percent of the energy required to produce primary aluminum, leading to fewer greenhouse gas (GHG) emissions. Using postconsumer metal as opposed to raw materials also greatly reduces the environmental toll (and economic costs) associated with long-distance transport.

Even for extracted aluminum, numerous U.S. primary aluminum producers have participated in the Environmental Protection Agency’s (EPA’s) Voluntary Aluminum Industrial Partnership (VAIP) program to both measure and reduce perfluorocarbon (PFC) generation. (PFC traps heat in the atmosphere, contributing to the greenhouse effect.) U.S. emissions of perfluorocarbon (PFC) from aluminum smelting have been reduced by more than 50 percent from 1990 levels, according to the American Architectural Manufacturers Association (AAMA). (For more, visit www.aamanet.org/pages/environmental[5].)

Environmental impacts associated with the finishing and pretreatment of aluminum require particular consideration. Anodizing, for example, involves an electrochemical process that increases the thickness of the naturally occurring, protective oxide layer. This finishing option has some benefits—it is cost-effective, results in a very hard, mar- and scratch-resistant surface, and has a popular metallic look. However, it is also water-intensive, using millions of gallons a year. Additionally, it requires the use of corrosive acids and chemicals, along with extremely high electricity consumption (which is typically generated using carbon fuels).

Buildings employing architectural coatings avoid the problems associated with anodizing. The chromates used in coating pretreatment have historically had environmental costs, as they may contain hazardous materials. However, those costs may be mitigated by the adoption of trivalent chromium or chromium-free pretreatment methods. To eliminate the use of chromium in the pretreatment process, conversion coatings have been developed that use ‘dry-in-place,’ nonreactive coatings applied in a thin film on the metal.

This only refers to the pretreatment process, and has nothing to do with 
the paint chemistry—whether liquid, powder, acrylic, or polyvinylidene fluoride (PVDF). Coatings currently sold in this market have been tested and perform well over this pretreatment process. There are no significant advantages to dry versus wet coatings, as both have their environmental benefits. For example, one advantage of powder is it has no volatile organic compounds (VOCs) at application. With wet paint, on the other hand, 
the solvent is destroyed, and the heat generated from this process fuels 
the curing oven, so much less natural gas is needed to cure wet paint 
than powder.

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Aluminum and building use phase
Other life cycle benefits associated with aluminum are conferred during building service life, and stem from recent technological improvements to enclosure systems. Historically, glazed openings were major points of unwanted heat loss or gain for building interiors. However, the advantages of glazed aluminum fenestration products ensured their continued popularity and drove several advancements in their technology. Most recently, engineered systems—polymers or structural plastics set into specially designed channels—were incorporated into the framing of glazed curtain wall units to successfully interrupt thermal bridging and prevent energy transfer. Given the proliferation of high-rise structures involving curtain 
wall construction, new improvements in curtain wall energy performance represent a major positive contribution in terms of life cycle performance.

For low-rise commercial or residential structures, metal-coil roofing can lower air-conditioning costs, reduce peak energy demand, and help mitigate urban heat island effects. In addition to the environmental benefits conferred by the roofing’s aluminum or zinc/aluminum-coated steel substrate, some specialty coatings contain ceramic and inorganic infrared (IR) reflective pigments, designed to reflect IR energy while still absorbing visible light energy. Reflective pigments appear the same color as traditional variations, but stay much cooler, lowering attic temperatures by up to 19 C (35 F).

For buildings of all sizes, modern aluminum alloys are structurally capable of supporting large expanses of glass, improving daylighting within buildings and reducing the need for electrical lighting.

Another common measure of a product’s environmental impact is durability. The strength of aluminum framing members can meet standards for both impact resistance (against windborne debris, etc.) as well as for blast loads (tested to 40,000 psi [275,790 kPa] without steel reinforcement). Metal roofing is durable enough to be specified (along with other nonflammable materials) by some local codes, especially in areas prone to forest fires.

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Any aesthetic or functional deterioration of a coated 
metal risks shortening the service life of a building or creating the need for extensive repairs. The extent of building surface area involved in high-rise architecture 
can make repair and refurbishment particularly challenging. Therefore, considerations such as the building finish 
become crucial.

Standards established by AAMA are voluntary and 
include specifications, performance requirements, and testing procedures for pigmented organic coatings on aluminum extrusions and panels (for factory-applied organic coatings only). As defined by AAMA:

• AAMA 2603, Voluntary Specification, Performance Requirements, and Test Procedures for Pigmented Organic Coatings on Aluminum Extrusions and Panels, identifies pigmented organic coatings that will provide a good level 
of performance, highlighted by one year of South Florida weathering exposure at a 45-degree angle;
• AAMA 2604, Voluntary Specification, Performance Requirements, and Test Procedures for High-performance Organic Coatings on Aluminum Extrusions and Panels, focuses on high-performance organic coatings that will provide and maintain a high level of performance, and requires five years of South Florida weathering; and
• AAMA 2605, Voluntary Specification, Performance Requirements, and Test Procedures for Superior-performing Organic Coatings on Aluminum Extrusions and Panels, focuses on organic coatings that will provide 
and maintain a superior level of performance, and requires a 10-year South Florida exposure.

Coatings meeting AAMA 2605 are appropriate for use on high-end building exteriors and are expected to last the lifetime of the building.

A related consideration when choosing a coating is the use of conflict minerals (i.e. those extracted in a geographic conflict zone and believed to fuel continued conflict.) It is advisable to work with a coating supplier able to provide a policy statement on its product in accordance with the U.S. Securities and Exchange Commission (SEC) final rule on conflict minerals.

Aluminum and waste
At the end of a building’s service life, aluminum is 100 percent recyclable. It can be repeatedly reused without any loss in quality or physical properties. Given recycling aluminum, as opposed to using new raw materials, reduces energy use 
by more than 90 percent, the aluminum recycling industry has tripled in recent decades. The increasing popularity of and demand for aluminum also enhances the profitability of aluminum recycling.

Conclusion
Understanding PCRs, EPDs, and LCAs—as well as the software tools that assist in their implementation—is now critical 
for any designer. LEED and other green programs are rewarding LCA more heavily, and as with other sustainability efforts, owners are becoming increasingly aware of LCA’s value. Fortunately, the demand for standardized life cycle information is being met by industry participation and disclosures.

Ben Mitchell is the extrusion coatings sales and marketing manager for AkzoNobel, a global paints and coatings company and producer of specialty chemicals. He has a bachelor’s degree in comprehensive science, as well as an MBA from Urbana University in Ohio. Mitchell started at AkzoNobel in 1990 as a lab chemist formulating polyvinylidene fluoride (PVDF) coatings, and moved into product management. 
He can be reached at ben.mitchell@akzonobel.com[8].

Vikas Ahuja is a senior account executive with Thinkstep, a company offering life cycle analysis (LCA) consulting, sustainability software development, and life cycle inventory databases. Ahuja holds degrees from the University of Chicago and University of South Florida, and has expertise in LCA, sustainable construction, and environmental transparency programs. He is based in Chicago and can be reached at vik.ahuja@thinkstep.com[9].

Source URL: https://www.constructionspecifier.com/assessing-aluminums-lca/

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