March 1, 2013
by Julie Rapoport, PhD, PE, LEED AP
When selecting products for a new project, architects, engineers, specifiers, and building owners consider many criteria, from aesthetics to strength to cost. Green buildings require an additional level of scrutiny to determine products’ environmental impacts in several categories, including operational and embodied energy, carbon footprint, and emissions.
Historically, evaluation of environmental impact relied on supplier claims, with some stakeholders researching specific aspects of a product’s composition and manufacture. Now, independently conducted lifecycle assessments (LCAs) and third-party-verified environmental product declarations (EPDs) are emerging as important tools for comparing some of the environmental attributes of similar products. (Another tool, Health Product Declarations [HPDs], which are recognized by the Leadership in Energy and Environmental Design [LEED] program, are even more nascent than EPDs. The topic will be worthy of an article in itself, once more of the initial groundwork has been completed and additional consensus achieved.)
With growing calls for increasing product transparency and the role it will likely play in U.S. Green Building Council’s (USGBC’s) newest version of Leadership in Energy and Environmental Design (LEED) due this summer, these resources are beginning to become mainstream for specification materials. LCAs and EPDs provide standardized methods for verifying manufacturers’ environmental claims and allow for accurate side-by-side product comparisons. As such, LCAs and EPDs are an excellent way to prevent ‘greenwashing’—defined by the Oxford English Dictionary as “disinformation disseminated by an organization so as to present an environmentally responsible public image.”
‘Product benchmarking’ is a baseline assessment of environmental impacts across all relevant categories—from extraction of the product’s raw materials to its end-of-life disposition. Benchmarking and quantification of environmental impacts are necessary elements of green building because they provide a better method of making apples-to-apples product comparisons. Accurate measurements of products’ environmental impacts enable reduction of the overall building’s environmental impact.
The three tools discussed in the following paragraphs—LCAs, PCRs, and EPDs—work together. Product category rules are first developed, a lifecycle assessment is performed according to the PCR, and an environmental product declaration publishes the results of the LCA.
A lifecycle assessment is an analysis of every component of a product’s manufacture and use. The lifecycle includes raw material extraction and transportation to manufacturing site (i.e. extraction phase), manufacturing, transportation to the jobsite and construction (i.e. construction phase), use, and end-of-life phase. (LCAs have some commonalities with lifecycle cost inventories [LCCIs]—used by individual companies for decades to evaluate their product supply chain for pinpointing inefficiencies and expense-cutting opportunities—but the two are not the same.)
An LCA that complies with International Organization for Standardization (ISO) 14040, Sustainability in Building Construction–Environmental Declaration of Building Products, is conducted by an independent third-party, ensuring unbiased results and confidence by end users.
This lifecycle phase include the impacts due to extracting raw materials and transporting them to the manufacturing site. For instance, products using aggregate as a raw material include the quarrying of the material and its transportation to the manufacturing site in their extraction phase. For short-haul distances, roundtrip transportation is considered because the truck that delivers the aggregate would directly return to the quarry for an additional load. (Where recycled materials are used, their impacts are allocated to their original product and to the new product according to a separate analysis outside the scope of this article.)
This phase includes all operational energy required to run the manufacturing plant, as well as all upstream energy to create the operational energy. (This is significant because for standard grid-delivered electricity, about two-thirds of the energy is lost during transmission. That is, for every 1 kWh of electricity used at the manufacturing site, about 3 kWh of electricity are made.) For product-specific LCAs and EPDs, this phase looks specifically at local energy grid sources.
This means identical plants manufacturing the same product can have different impacts in the manufacturing phase depending on where in the country they are located and what kind of fuel is used to generate electricity (e.g. manufacturing sites relying on coal combustion will have a higher carbon footprint than those relying on natural gas combustion, as the carbon emissions per unit of energy for coal are about twice as high as those for natural gas). Where manufacturers use renewable energy, such as locally mounted solar panels, there is a corresponding reduction in environmental impacts.
This phase includes transportation of finished products to the jobsite and accessory materials required for construction, as well as the construction itself. For example, the lifecycle of brick includes the use of mortar because a brick wall cannot generally be built or function without mortar. Depending on the distance the finished goods are transported, the LCA will consider one-way or two-way transportation. For example, brick and ingredients for mortar are generally moved on flatbed trucks on an as-needed basis by contract haulers. Consequently, one-way transportation is considered for this phase, as back-hauls on flatbed trucks are common and expected.
This phase includes the impacts of using the product over its expected service lifetime, including any maintenance that is expected and required. PCRs and EPDs define the expected service lifetime of the product under consideration. For bricks, a reasonable service lifetime is 80 years. Tuck-pointing (i.e. repair) of mortar could be expected once during this service lifetime. The definition of the service lifetime is helpful when EPD users want to compare durability and longevity of different products in the same category. For example, an asphalt pavement does not have as long a service lifetime as its concrete counterpart, and users can take this into account (in the context of other variables) when specifying products.
This phase includes the impact of a product’s deconstruction and final disposition. Where recycling occurs, this phase includes the impacts of recycling a product, both positive and negative. For example, crushing a brick wall and recycling it into sub-base for roads might have a net decrease in carbon impact (because virgin aggregate does not need to be quarried for the road sub-base) and a net increase in energy impact (because the energy required to crush the brick wall is part of this phase).
A product category rule (PCR) is the standardized method for conducting and reporting an LCA. The PCR ensures all products in a certain category (e.g. ready-mix concrete or roofing products) are measured the same way and environmental impacts are quantified in the same way in each lifecycle phase. The PCR defines boundaries for measurement—such as cradle-to-gate or cradle-to-grave—as well as the functional unit measured (e.g. 1 m3 of concrete, or 1 square of roofing material). (The measurement of 1 square of roofing material is equivalent to 9.3 m2 [100 sf].)
PCRs are developed by industry experts and stakeholders using a consensus-based, collaborative, transparent process. They are then verified by an expert review panel. The entire process must follow guidelines generally laid out in ISO 21930, Sustainability in Building Construction–Environmental Declaration of Building Products.
PCRs are costly and, as a result, there is not currently a large number of them. However, this is starting to change, and more are being developed each year. For example, the Institute for the Market Transformation to Sustainability (MTS) has developed a unique universal ISO-compliant PCR that can apply to any environmentally preferable product. It was rigorously developed by independent third-party LCA experts and open to a public comment period. The only variable in MTS’ PCR is the functional unit, which must be defined for each product. MTS administers Sustainable Materials Rating Technology (SMaRT), which is the leadership sustainable products standard. MTS also acts as the program operator for SMaRT EPDs, which follow the SMaRT PCR.
An environmental product declaration is a document created by the manufacturer to show results of a lifecycle assessment. It is verified by an expert and approved by a program operator, such as UL Environment (ULE) or the aforementioned MTS.
EPDs that comply with ISO 14025, Environmental Labels and Declarations–Type III Environmental Declarations: Principles and Procedures, enable stakeholders to make direct accurate comparisons of some environmental attributes—such as carbon footprint and embodied energy—of similar products. This enables stakeholders to assess products with the same traditional attributes (e.g. strength, durability, cost) and choose the product with the lowest environmental impact of interest.
EPDs can have requirements for how often they must be renewed. For example, SMaRT EPDs used by this author’s firm must be renewed every three years. During the renewal process, aspects like energy input can be revisited and updated.
Impact categories describe the effect of a product lifecycle—or individual phases—on specific areas of concern. Impact categories include:
PCRs define which impact categories must be reported in each EPD. Of course, EPDs can always report more impact categories than required by the PCR. (For example, the SMaRT PCR also includes human health air pollutants, human toxicity, and eco-toxicity for air, soil, and water.) Design professionals and owners should consider which impact categories are of greatest interest for their projects. For instance, while carbon footprint is likely always a concern, impact on water resources might also be of particular consideration in the arid Southwest.
Boundaries are an important element in LCAs and associated EPDs. Simply put, where does the product system start and stop? Does the LCA consider the electricity used to power the plant and also the energy required to create that electricity? Does the EPD include cradle-to-grave impacts (i.e. all lifecycle phases) or only cradle-to-gate impacts (i.e. limited to raw material extraction and manufacturing phases, but not construction, use, or end-of-life phases)?
EPDs present results of the lifecycle assessment. It is necessary to understand which boundaries are used to accurately compare environmental data. Typically, EPDs show information with one of the following sets of boundaries (Figure 1):
The PCR specifies what boundaries should be used in the LCA. (For example, ISO 21930 requires the consideration of energy needed to generate electricity, not simply the electricity used at a manufacturing site.)
From a stakeholder’s perspective, the most versatile EPDs present impacts by each lifecycle phase. This allows users to compare environmental impacts with appropriate boundaries in mind. (This is important if one manufacturer has published a cradle-to-gate EPD and another has published a cradle-to-grave EPD. In this situation, for a meaningful comparison, the user should look at cradle-to-gate impacts, as it is the information available for both products.)
ISO 21930 has requirements regarding which impact categories must be included in EPD impact category tables. For example, Figure 2 shows an impact category table from an EPD for brick made with the alternative ingredient of fly ash, rather than fired-clay or shale. The white items are categories required by ISO, while the highlighted categories are additional categories required by the specific PCR used for the LCA for this EPD. As discussed, PCRs ensure each EPD (in the product category) shows impacts in the same categories, determined using similar methods.
Before environmental considerations became paramount, design professionals typically chose products based on specific features such as aesthetics, technical performance, and price. EPDs provide further information for consideration. For instance, in addition to selecting a product based on price, color, and performance, a design professional can also choose the material with the lowest carbon footprint or embodied energy. Using EPDs, some environmental impacts can be compared directly. As discussed, one should consider which impact categories are of greatest interest for each project.
Comparing products without EPDs
In the ideal future, most products will have EPDs. At present, making accurate and meaningful comparisons of similar products can require a fair amount of effort from the stakeholder.
In some situations, there may be one EPD published for a specific product and generic industry data might be available for other products. For instance, in the aforementioned EPD for fly ash brick, a formal LCA was conducted by architecture firm Perkins+Will using Gabi 5.0—software to perform the lifecycle assessments.
There are not yet any EPDs for clay brick (both are in the same product category). However, a generic LCA for clay brick exists in the National Institute of Standards and Technology (NIST) Building for Environmental and Economic Sustainability (BEES) Online database.
The data from the fly ash brick EPD can be compared to the NIST BEES Online data to draw some conclusions. The user needs to research the data to understand boundaries used in the fly ash brick LCA (presented in the EPD) and the clay brick LCA to ensure an accurate comparison is made. In this case, the boundaries and assumptions are the same for both types of bricks through the cradle-to-gate phases, but change in the gate-to-grave phases. Thus, the meaningful comparison is made using cradle-to-gate boundaries. The fly ash brick manufacturer reported environmental impacts by individual lifecycle phase, so determining the cradle-to-gate impact from the EPD is relatively easy.
In other situations, when no (or questionable) lifecycle data is available, it can be worth contacting product manufacturers to ask questions regarding environmental impact. Even a high-level understanding of a manufacturing process can provide some insight into environmental impact. For example, if a product (such as a brick) requires days of high-temperature heat treatment, a user can determine the product likely has a high carbon footprint and embodied energy.
Environmental product declarations and lifecycle assessments are important tools for assessing the environmental impact of materials and associated product selection decisions. LCAs provide design professionals with additional information when choosing among products; they are one more method for weighing the attributes of material selections. As always, design professionals must exercise professional judgment when choosing materials.
Even in the absence of ISO-compliant EPDs or LCAs based on PCRs, it is important to gather environmental data for the products in buildings. Such educated selections are perhaps the best way to avoid ‘greenwashing.’ These selections can also play a significant role in reducing a building’s environmental footprint before a single tenant takes occupancy. Though it can take some effort now, as design professionals increasingly ask for environmental impact information, more will become available. Additionally, as the demand grows for independent, standardized, verified product information, the comparison process will get easier.
Julie Rapoport, PhD, PE, LEED AP, is vice president of engineering at CalStar Products. She has more than a decade of experience in the fields of building technology, concrete products, and cementitious materials. Rapoport earned her PhD at Northwestern University (Evanston, Illinois) and her degrees in physics and English from Williams College (Williamstown, Massachusetts). She can be reached by e-mail at firstname.lastname@example.org.
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