LEED & HDG
As LEED® is the most common method for measuring sustainability, often specifiers question whether hot-dip galvanized steel can contribute credits. 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 contributes points under Materials & Resources Credit 4: Recycled Content category. LEED® requires the following to earn points:
Use materials with recycled content such that the sum of postconsumer recycled content plus ½ of the preconsumer content constitutes at least 10% or 20% based on cost, of the total value of the materials in the project. The minimum percentage materials recycled for each point threshold is as follows:
- 10% – 1 point
- 20% – 2 points
The recycled content of a material assembly is determined by weight, and the recycled fraction is then multiplied by the cost of the assembly to determine the recycled content value. Hot-dip galvanized steel is both the material and the building product (the zinc metallurgically reacts with the iron in the steel, becoming one product); therefore, the value of the steel building product is directly multiplied by hot-dip galvanized steel’s recycled content.
With more than 70% combined recycled content, hot-dip galvanized steel easily meets the requirements of Materials & Resources Credit 4: Recycled Content, contributing two points.
Other Possible LEED Points
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. The requirement is:
Use materials or products that have been extracted, harvested, or recovered and manufactured within 500 miles of the project site for a minimum of 10% or 20%, based on cost, of the total materials value. If only a fraction of a product or material is extracted, harvested, or recovered and manufactured locally*, then only that percentage (by weight) can contribute to the regional value. The minimum percentage regional materials for each point threshold is as follows:
- 10% – 1 point
- 20% – 2 points
*Per USGBC, the steel fabricator is the final point of assembly and is therefore the manufacturer in terms of LEED® Local/Regional Materials credits (unless steel is delivered directly from the mill to the site).
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. The LEED® 2009 requirement is:
Use salvaged, refurbished or reused materials, the sum of which constitutes at least 5% or 10%, based on cost, of the total value of materials on the project. The minimum percentage materials reused for each point threshold is as follows:
- 5% – 1 point
- 10% – 2 points
Innovation in Design Credits
In addition to the Materials and Resources Credits already outlined, hot-dip galvanized steel may be able to contribute “bonus” points under Innovation in Design (ID) Credit 1. There are two paths for earning credit and depending on the job, HDG may contribute in both.
Path 1: Innovation in Design (1-5 points)
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.
Achieve significant, measurable environmental performance using a strategy not addressed in the LEED® 2009 for New Construction and Major Renovations Rating System.
Example: 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.
Path 2: Exemplary Performance (1-3 points)
Exemplary performance point for MR Credit 4 is always achievable when utilizing HDG due to the 70% recycled content value. The additional exemplary point for MR Credit 5 or other areas would be on a job-by-job basis.
Achieve exemplary performance in an existing LEED® 2009 for New Construction and Major Renovations prerequisite or credit that allows exemplary performance as specified in the LEED® Reference Guide for Green Building Design & Construction, 2009 Edition. An exemplary performance point may be earned for achieving double the credit requirements and/or achieving the next incremental percentage threshold of an existing credit in LEED®.
- 1 point for MR Credit 4: Recycled Content (exceeding by an additional 10%)
- 1 point for MR Credit 5: Regional Materials (if exceeded by an additional 10%)
*LEED®-NC Versions 2.2 and 2009