When introduced in 2014, the U.S. Green Building Council’s LEED v4 heightened awareness of environmental product declarations or EPDs. Among significant changes to the LEED Materials & Resources credit criteria, LEED v4 now bestows a modest one point for projects with at least 20 EPDs from different construction material manufacturers. Given that buildings and sites typically contain thousands of products, this seems a small requirement by LEED v4.
One intent of this credit is to raise awareness of EPDs among construction material suppliers. This requirement has led many construction materials industries to first create product category rules (PCRs) according to ISO standards. PCRs prescribe requirements for defining the impacts of manufacturing a product, as well as outline the elements of a life-cycle assessment (LCA) of environmental impacts from manufacturing. The LCA forms the basis for creating an EPD.
EPDs list environmental impacts from manufacturing a product. They have been compared to reading a nutrition label on food packaging. Rather than fat, carbohydrates, proteins and vitamins, EPDs list the following impacts: global warming potential (carbon emissions); sulfur-dioxide, ozone and smog-type air pollutants; total energy consumed; use of renewable resources; depletion of non-renewable natural resources; nutrient emissions into waterways; and fresh-water use.
A practical yardstick for measuring these impacts is typically a unit of volume or mass of the finished construction product. For segmental concrete paving units, this is a cubic yard or meter of concrete. Most impacts per cubic yard of concrete are from carbon emissions due to producing cement and from generating electricity to run a manufacturing plant. Obviously, the energy source to make cement and electricity influence carbon emissions. EPDs favor hydroelectric, nuclear, wind and solar energy with lower carbon emissions compared to coal, gas or oil-fueled sources.
Now that ASTM issued a PCR for segmental concrete pavement products, it’s up to manufacturers to conduct LCAs, then produce and publish EPDs on their products. While the market isn’t consistently or even intermittently demanding EPDs from concrete paver manufacturers, the industry is preparing for the inevitable change. California manufacturers will likely be the first with EPDs, since that state imposed a legal mandate to trim carbon emissions. To assist the education process, the ICPI Foundation for Education & Research recently developed a guidebook for manufacturers on creating LCAs and EPDs. ICPI also developed a manufacturing material and energy-use inventory spreadsheet tool for its members.
Comparing EPDs among manufacturing segmental concrete paving products, asphalt and ready-mix concrete requires nearly equivalent PCRs. The asphalt industry will weigh in when their PCR is completed late this year or next.
While LEED and other sustainability evaluation tools have taken modest steps to raise EPD awareness in the North American construction world, where are EPDs ultimately going? They will become a critical source of data that will eventually feed into evaluating environmental impacts from a product’s construction, life and disposal/reuse. This is already happening in the building design world. It’s just starting in the pavement world.
Segmental concrete paving products are in a unique position to offer lower environmental impacts by not requiring huge paving machines and concomitant fuel consumption during construction. During their life, segmental concrete pavements offer immediate reuse in-service, a significant benefit for cities. Asphalt and cast-in-place concrete do not; those materials are removed and landfilled or later recycled.
Quantifying differences among construction, lifetime and end-of-life impacts will become increasingly important to municipal transportation agencies in the coming years.
Aggregates supplies are decreasing in some regions. Asphalt isn’t cheap. Transportation agencies are expected to build, maintain and rehabilitate pavements with less money and make them last longer.
Like Europe, agencies here will eventually move toward bidding material, construction and project maintenance life-cycle assessments. Maintenance pricing and LCA bids will spawn risk assessment/financing companies. (Maintenance price bids are already happening with some ICPI members selling permeable interlocking concrete pavements.)
All of these tools will ultimately save agencies money. LCAs will grab their wallets. That will get their attention.