By Julie Rapoport
Architects designing Hancock Elementary School in Kiln, Miss. – slated to be the first LEED-certified K-12 school in the state – used product benchmarking tools to help select the CalStar bricks and the bio-based floor tiles.
Selecting masonry products requires consideration of a number of attributes – performance, aesthetics and cost, to name just a few. If you’re working on a green building, the list grows. Products for sustainable projects require an additional level of scrutiny to determine environmental impacts, including operational and embodied energy, carbon footprint, and impact on human and ecosystem health.
Historically, the evaluation of environmental criteria relied upon manufacturer claims, with some stakeholders researching specific aspects of a product’s composition and manufacture. But the emergence of independently conducted life cycle assessments (LCAs) and third-party-verified environmental product declarations (EPDs) provides specifiers with helpful tools for accurately comparing similar products’ environmental attributes.
What is product benchmarking?
Product benchmarking provides standardized methods for verifying manufacturers’ environmental claims and allows for accurate side-by-side comparisons of the environmental impacts of two or more products. This type of evaluation is key to the green building process, because it provides a truly transparent method of making consistent product comparisons. Accurate assessments of products’ environmental impacts enable reduction of the overall building’s environmental impact.
As with many fields, product transparency has its own specialized lingo.
The International Organization for Standardization – an independent body that creates the rules for how product category rules should be written and how Life Cycle Assessments should be conducted.
|Figure 1 – This EPD, published by CalStar Products in November 2012, shows the third-party-verified carbon footprint and embodied energy of its bricks. The EPD also contains background information on how the data were collected and details on attainable LEED credits.|
A life cycle assessment (LCA) is an analysis of every component of a product’s manufacture and use. The life cycle includes raw material extraction and transportation to the manufacturing site (extraction phase), the manufacturing phase, transportation to jobsite and construction (construction phase), use phase, and end-of-life phase.
An ISO-compliant life cycle assessment is conducted by an independent third party, ensuring unbiased results and confidence by end users.
A product category rule (PCR) is the standardized method for conducting and reporting a life cycle assessment. The PCR ensures that all products in a certain category (e.g., ready mix concrete or roofing products) are measured the same way in each life cycle phase and that environmental impacts are quantified in the same way. The PCR defines the boundaries for measurement (such as cradle-to-gate or cradle-to-grave), as well as the functional unit measured (e.g., one cubic yard of concrete or 100 square feet of a roofing material).
PCRs are developed using a consensus-based, collaborative, transparent process by industry experts and stakeholders. They
are then verified by an expert review panel. The entire process must follow certain ISO guidelines.
At present, the number of PCRs is not large. This is starting to change, with more PCRs developed each year.
An environmental product declaration (EPD) is a document created by a manufacturer to show the results of a life cycle assessment of a product (see Figure 1). It is verified by an expert and approved by a program operator, such as UL Environment (ULE) or the Institute for Market Transformation to Sustainability (MTS).
EPDs enable stakeholders to make accurate, direct comparisons of environmental attributes – such as carbon footprint and embodied energy – of similar products.
These three acronyms work together: Product category rules are developed; a life cycle assessment is performed according to the PCR; and an environmental product declaration publishes the results of the LCA.
Impact categories describe the effect of a product on specific areas of concern. Impact categories include, but are not limited to, global warming potential (aka, carbon footprint), fossil fuel depletion (aka, embodied energy), smog and ozone depletion. 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. When evaluating product choices, specifiers can consider those impact categories that are of greatest importance for each project. For instance, while carbon footprint is likely always a concern, in arid regions, impact on water resources might also be an important consideration.
Figure 2 – When comparing products, it’s important to compare them within the same lifecycle boundaries. For example, the cradle-to-gate lifecycle of concrete shown here includes raw material extraction through the manufacturing process, but not transportation to the jobsite, construction or end of life.
Boundaries are an important element in life cycle assessment and associated EPDs (see Figure 2). 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 (all life cycle phases) or only cradle-to-gate impacts (raw material extraction and manufacturing phases, but not construction, use, or end-of-life phases)?
The PCR specifies what boundaries should be used in the LCA. EPDs present the results of the LCA. It is necessary to understand which boundaries are used to accurately compare environmental data.
Comparing products without EPDs
Ideally, in the future most products will have EPDs. Without them, making accurate and meaningful comparisons of similar products can require a fair amount of effort from the specifier.
In some situations, there might be one EPD published for a specific product, and generic industry data might be available for other products. For instance, an EPD exists for fly ash bricks but not yet for clay bricks. However, a generic LCA for clay bricks exists in the NIST BEES Online database. The data from the fly ash bricks EPD can be compared to the NIST BEES Online data to draw some conclusions. The user needs to delve into the data to understand the boundaries used by both the fly ash bricks LCA (presented in the EPD) and the clay bricks LCA to assure a meaningful, accurate comparison is made.
In other situations, when no life cycle data (or questionable life cycle data) are 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 insights (e.g., Is one product more energy intensive to produce? Does one product require a lot of washing?).
Even in the absence of EPDs or LCAs, it is important to gather environmental data for the products in your buildings. These considerations can play a significant role in reducing the environmental footprint of buildings before a single tenant takes occupancy. Such educated selections also are the best ways to avoid greenwashing. Though it can take some effort now, as stakeholders increasingly ask for environmental impact information, more will become available. As the demand for independent, standardized, verified product transparency information grows, the comparison process will get easier.
This article first appeared in Masonry Magazine.
Julie Rapoport is VP of product development at CalStar Products.
Limestone Powder Enhances Performance of ‘Green’ Concrete
|Adding limestone powder to green concrete mixtures – those containing substantial amounts of fly ash, a byproduct of coal-burning power plants – can significantly improve performance, report researchers from the National Institute of Standards and Technology (NIST) and the Federal Highway Administration (FHWA).
The laboratory results suggest a path to greatly increasing the use of fly ash in concrete, leading to sizable reductions in greenhouse gas emissions, energy use, construction costs and landfill volumes. Global production of cement for concrete accounts for 5 percent to 8 percent of human-caused greenhouse gas emissions.
Currently, fly ash accounts, on average, for about 15 percent of the binder powders in the ready-made concrete used in the United States. To produce a more green concrete, NIST is researching new material combinations and procedures that could help the industry use fly ash to routinely replace 40 percent to 50 percent of the ordinary portland cement (OPC), the main binding and hardening agent in concrete.
Because of delays in setting times and questions about its strength in the first few days after application that both “impact its constructability,” says NIST chemical engineer Dale Bentz, “green concrete has been a tough sell in large parts of the construction industry.” However, Bentz and his FHWA colleagues found that a “judicious combination of fine limestone powder” can help to put these concerns to rest.
So-called high-volume fly ash “ternary” mixtures (including some limestone) that replace between 40 percent and 60 percent of the cement portion not only set at rates comparable to those for typical concrete, but also were superior in terms of key properties.
Initially, the strength of the green concrete mixtures after 28 days slightly lagged that of concrete without any fly ash. However, the team was able to tweak the fly ash-limestone-OPC mixture to overcome the gap, primarily by lowering the water-to-powder ratio and switching to a different standard composition of OPC (ASTM Type III).
Today, global production of OPC totals about 3.5 billion metric tons (3.85 billion tons) annually. Generation of each ton of OPC emits about a ton of carbon dioxide into the atmosphere.
Greater use of high-volume fly ash mixtures could reduce this environmental burden and, at the same time, reduce costs for concrete construction, says Bentz. For Bentz and his team, the next research challenge is to test their limestone-enhanced mixtures in the field, where curing conditions can vary.
For more information, contact Mark Bello, 301-975-3776.