LEED & HDG
As LEED® is the most common method for measuring sustainability, often specifiers question whether hot-dip galvanized steel can contribute credits. The hot-dip galvanizing process is not LEED® rated, because processes and products are categorized as contributing to the overall LEED® score for a building under construction or completed. Hot-dip galvanized steel can contribute to your LEED® score in the Materials & Resources section in both the 2009 version as well as the new v4. Let's take a look at both in more detail.
The main area where galvanizing contributes to LEED® 2009 is due to the recycled content. The Materials & Resources Credit 4: Recycled Content category specifically focuses on increasing the use of building products with high recycled content, thus reducing impacts caused by extraction and processing of raw metal and ores. The two primary components of hot-dip galvanized steel (steel and zinc) have high recycling and reclamation rates. The recycling rate, which is factored into the LEED® rating, considers how much of a particular product comes from recycled sources. The reclamation rate, which measures how often a product is actually recycled at the end of its useful life, is not currently used in the LEED® rating, but is also an important environmental indicator to consider.
|1. International Zinc Association (IZA) Zinc Recycling, 2004
2. Steel R ecycling Institute Steel Lakes LEED with Recycles Content, March 2009
Because of these high recycling rates, hot-dip galvanized steel can contribute 2 points in the key area of Materials & Resources Credit 4: Recycled Content for having more than 20% of the total value of the material coming from recycled sources. Additionally, because of the extremely high recycling rate of both zinc and steel, HDG can actually earn an “extra credit” point under Innovations in Design Credit 1: Path 2 Exemplary Performance because the recycled content actually exceeds 30%.
Other Possible LEED 2009 Credits
Hot-dip galvanizing may (on a job-by-job basis) be able to provide additional LEED® 2009 points under the following areas:
- MR Credit 5: Regional Materials - Because USGBC has now recognized the steel fabricator as a final point of assembly, hot-dip galvanized steel may also be able to provide credits under MR Credit 5. This would be determined on a job-by-job basis and awarded if the fabrication and galvanizing facility are within a 500-mile radius of the job-site. Credits available: 10% – 1 point; 20% – 2 points
- MR Credit 3: Materials Reuse - Similar to MR Credit 5, this would be evaluated on a job-by-job basis. There are a number of examples of material from one demolition site being reused on the existing site during reconstruction or used at another location. Credits available: 5% – 1 point; 10% – 2 points
- Innovation in Design Credit 1 Path 1 : Innovation in Design - There are numerous possibilities here with sufficient explanation of how the use of hot-dip galvanized steel is adding to the overall environmental performance of the building in a way not addressed in the other credits. One example would be Material efficiency - utilizing hot-dip galvanized Architecturally Exposed Structural Steel (AESS) eliminates additional materials required for finishing as well as additional materials for future maintenance and/or the use of castellated beams (in a parking structure) provides the same strength with less material.
- ID Credit 1 Path 2: Exemploary Performance - This credit can be achieved if a material can achive double the credit requirement and/or achieve the next incremental percentage threshold of an existing credit. Exemplary performance point for MR Credit 4 is always achievable when utilizing HDG due to the 70% recycled content value. An additional exemplary point for MR Credit 5 or other areas would be on a job-by-job basis.
The new LEED® v4 (passed in 2013) is quite different than its previous versions. The USGBC is transitioning LEED from a prescriptive checklist to a more definitive measure of environmental impact from start to finish. The goal is more transparency in materials, so specifiers can make the best choices. The new version has a heavy focus on Environmental Product Declarations (EPDs) which detail the materials used in a building and their economic impact (which are founded on Life-Cycle Assesments (LCAs)). There also is a heavy emphasis on the supply chain – knowing not only what the final manufacturer did to the material, but where they acquire their base material, and how responsibly it is mined, etc. Finally, there is an opportunity for credit if the material you are using has a published material ingredient list or Health Product Declaration (HPD).
The AGA is currently working on an industry-wide EPD, and have already developed HPDs based on the type of zinc in the galvanizers kettle. The International Zinc Association (IZA) and its mining members are working on more information related to zinc and the supply chain.