environmentaly friendly

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 half 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%)

Hot-Dip Galvanized Steel: Low in Economic Cost

The initial cost of hot-dip galvanized (HDG) steel is the final cost. Once HDG steel is in place, it rarely needs maintenance for 75 years or more, even in the most corrosive industrial environments. Therefore, utilizing HDG allows maintenance budgets to be allocated to new projects and programs. With HDG steel, there is no expensive labor, site precautions and protection, surface preparation, and materials needed every 12-15 years as is required with paint.

As shown below, HDG’s time to first maintenance is a key contributing factor to low economic cost.

Galvanized Steel Contributes LEED® Credits

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.

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:

Zinc Recycling

Zinc brings a multitude of economic and social benefits to society. Man has found a wide range of uses for this versatile natural element whose properties are valued in many industries.

The most important application of zinc is protecting steel from corrosion by hot-dip galvanizing. Steel is one of the most widely-used materials on the planet, and thanks to zinc, steel’s durability can be prolonged. Both steel and zinc are 100% recyclable. The zinc-steel combination has significant economic benefits in terms of life-cycle costs. Improved air quality in many industrialized countries, with diminishing levels of sulfur dioxide (SO2), means today zinc coatings provide even longer protection for steel.

Increased attention to life-cycle costing is motivating designers, specifiers and investors to opt for zinc-coated steel in many traditional and new applications, from construction to automobiles, from electricity distribution poles to safety barriers, from farm gates to ski-lifts.

Zinc, the 27th most common element in the Earth’s crust, is fully recyclable. At present, approximately 70% of the zinc produced originates from mined ores and 30% from recycled or secondary zinc. The level of recycling is increasing in step with progress in zinc production and zinc recycling technologies.

Today, over 80% of the zinc available for recycling is recycled. Zinc is recycled at all stages of production and use - for example, from emissions that arise during the production of galvanized steel sheet, from scrap generated during manufacturing and installation processes, and from products at the end-of-life. The pie chart below describes the percentage of recovered zinc from various products manufactured with zinc.

The life of zinc-containing products is variable and can range from 10-15 years for cars or household appliances, to over 100 years for zinc sheet used for roofing. Street lighting poles made of zinc-coated steel can remain in service for 50 years or much longer, and transmission towers for over 70 years. All these products tend to be replaced due to obsolescence, not because the zinc has ceased to protect the underlying steel. For example, zinc coated steel poles placed in the Australian outback a hundred years ago are still in excellent condition.

The presence of zinc coating on steel does not restrict steel’s recyclability and all types of zinc-coated products are recyclable. Zinc coated steel is recycled along with other steel scrap during the steel production process – the zinc volatilizes and is then recovered.

The supply of zinc-coated steel scrap is expected to double over the next five years, as more zinc-coated vehicles enter the recycling stream.

ZINC COATING

Zinc protects the steel in 2 ways. The first is by barrier protection. Zinc provides a tough metallurgical bonded zinc coating, which completely covers the steel and seals it from the environment.

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GALVANIZING PERFORMANCE

For over 250 years, hot-dip galvanizing has proven to be a high quality and cost effective corrosion protection coating. In most applications hot-dip galvanizing is superior to paint.

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