Hot-dip galvanized (HDG) steel is 100% recyclable and has a reclamation rate for zinc and steel of 80% and 100%, respectively. Based on such a high recycling rate, HDG steel may contribute one point/credit toward LEED® certification under both paragraph 4.1 and 4.2 of the Materials & Resources Credit 4: Recycled Content category.
Learn more by downloading the Hot-Dip Galvanizing (Zinc+Steel) takes LEED® with Recycled Content publication.
LEED® as an Indicator of “Greenness”
Though LEED® can be a bit simplistic, if you are seeking a LEED® rating, hot-dip galvanizing can contribute points to your LEED® score due to its high recyclability. Steel, the most recycled material in the world, and zinc are both 100% recyclable infinitely without the loss of any mechanical properties.
There are two measures of recyclability: percentage of recycling content and reclamation rate. Recycling content refers to the amount of the product produced from recycled sources. The reclamation rate measures how often a product is actually recycled at the end of its useful life.
Hot-dip galvanized steel rates highly on both measures, and the primary reason more recycled zinc is not used is it is unavailable – it is so durable it is still in use! Currently, only the percentage of recycled content is considered in garnering LEED® points, and not the equally important reclamation rate.
The table below shows the Recycling and Reclamation Rates for both zinc and steel:
LEED® Points HDG Can Contribute
Due to these high recycling rates, hot-dip galvanized steel always contributes two points under the following category:
MR Credit 4: Recycled Content
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 value of a material assembly is determined by weight. The recycled fraction of the assembly is then multiplied by the cost of assembly to determine the recycled content value.
There may be other areas hot-dip galvanized steel contributes points to your LEED® score on a case-by-case basis and thus each project should be evaluated individually. Here are a few additional areas utilizing hot-dip galvanized steel may contribute points:
MR Credit 5: Regional Materials
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
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
ID Credit 1: Innovation in Design
Path 1: Innovation in Design (1-5 points)
Achieve significant, measurable environmental performance using a strategy not addressed in the LEED® 2009 for New Construction and Major Renovations Rating System.
- 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
Path 2: Exemplary Performance (1-3 points)
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 (exceeding by an additional 10%)