As a market transformation catalyst, the next version of the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) program further incentivizes energy conservation and reduced carbon emissions for products selected for neighborhood, site and building design, construction and maintenance. LEED v4 will be balloted and published later this year. This article reviews some important changes that apply to segmental concrete paving products.
One of the most notable changes is the application of environmental impact analysis to building and paving products.
LEED v4 grants points to productswhereas the paving industry, or more importantly, the concrete paver manufacturer issues an environmental product declaration (EPD). Some in the industry have described an EPD akin to a nutrition label on food packaging. Instead of nutrition characteristics, building products will list energy use, carbon emissions and other environmental impacts. This information provides designers and project owners with some basis for product comparison. Though building material selection isn’t strictly based on EPDs, it is still an importantconsideration regarding cost, performance and appearance.
ABCs of EPDs
A key notion behind EPDs is that the environmental impacts of various products can be compared as long as the basis of measurement and the analysis boundaries are the same.
Analysis boundaries of environmental impacts include extraction, manufacturing, construction, use and end-of-life. Unlike other construction products (e.g., stainless steel doors), construction, use and end-of-life for concrete products (and other paving materials) have wide variations that are difficult to quantify. Thus, boundaries are generally drawn around extraction and manufacturing, often called cradle-to-gate impact analysis.
EPDs are based on two other key documents. The first is a life cycle assessment (LCA) that quantifies environmental impacts of a product. Per ISO 14040, environmental impacts include:
- Carbon footprint (emissions)
- Fossil fuel depletion
- Water depletion
- Metal depletion
- Ozone depletion
The second document is a product category declaration (PCR). This is standard method for reporting an LCA and defines what impacts must be reported in an EPD. PCRs help ensure that similar products quantify impacts the same way. Bases for measuring environmental impacts are also included. For example, for concrete materials,energy consumption is often reduced to kilowatt-hours per cubic meter of concrete.
Once a PCR has been written, like an EPD, it should be reviewed and certified as compliant with ISO requirements by an independent third party. From a practical perspective: First a PCR is written and receives a third-party review; then an LCA is conducted; and from that an EPD is developed, which also receives outside review and ISO-compliance certification.
LEED v4 offers ¼ credit for EPDs from a product manufacturer with no third-party review or certification. If third-party certification is provided, then ½ credit is earned for an industry-wide product EPD and 1 credit for an EPD provided by the product manufacturer.
While the expense to obtain a PCR and EPD seems large in relation to the number of credits offered, LEED v4 may develop additional credits based on these environmental impact assessment tools in the future. For now, LEED v4 is a first effort in quantifying the environmental impacts of products. Another benefit is that an LCA and EPD can help manufacturers identify areas for cost-saving conservation measures.
In summary, LEED v4 provides a more complex structure for evaluating sustainability of building products, including concrete unit paving products. The introduction of PCRs and EPDs can enable some comparison among pavement materials, at least within cradle-to-gate boundaries. With LEED v4, the industrycan expect further affirmation of segmental concrete paving products as environmentally sustainable. One thing that hasn’t changed is the crediting categories. They remain:
- 40-49 = Certified
- 50-59 = Silver
- 60-79 = Gold
- 80+ = Platinum