In the past, evaluations of building material sustainability focused on a limited number of factors such as recycled content or the Life Cycle Inventory (e.g. environmental impact during mining, extraction and production). Sustainable building evaluation methods are evolving and are including more complete assessments of the impact of material selection on the carbon footprint of a building over its intended service life.
World Green Building Council member countries, such as Canada and USA, are developing Life Cycle Assessment (LCA) methods that require the materials used for large building systems (e.g. structural components, walls, roofs, etc.) to last the life of the building without replacement. Similar assessments are being adopted in building codes. These changes are encouraging designers to ask more questions about material performance.
Material comparisons fare increasingly including data on recycled content, diversion from landfills (recapture rate), potential for product reuse, expected service life, maintenance requirements, impact on energy and water consumption, and influence on indoor air quality and light. When these complete analyses are done, nickel-containing architectural stainless steels (e.g. 304/304L, 316/316L) are consistently among the most environmentally friendly metals commonly used in construction.
Many examples of stainless steel ‘s longevity can be found in the Nickel Institute brochure Timeless Stainless Architecture but there are many new buildings that are being designed for 50, 100 or even longer service lives where stainless steel was used for exterior systems because of its corrosion resistance, durability, and low maintenance. The applications where stainless steel is contributing to longevity, energy reduction, and other sustainable design concepts include roofing, wall panels, and sunscreens.
Stainless steel is also a sustainable choice for interior building surface applications because it produces no VOC emissions. This makes it ideal for buildings where control of the interior air quality is critical, such as museums, laboratories, archives, medical facilities, and but it is also ideal for any structure where low air volatile organic compound (VOC) levels are desired.
Internationally, the average recycled content of stainless steel is 60% with approximately 25% of the input material from end-of-service life recycled products and 35% from production and manufacturing. An interactive ISSF (International Stainless Steel Forum) presentation summarizes this research.
In parts of the world where stainless steel has been used in larger quantities for a longer period of time and scrap is more readily available, the scrap content of the stainless steels that are commonly used in architecture, building and construction is much higher. In North America, the Specialty Steel Industry of North America (SSINA) reports that typical recycled content levels are between 75 and 85% in their LEED Fact Sheet.
The ISSF video Recycled for Lasting Value provides an overview of stainless steel recycling.
Diversion From Landfills/Recapture Rate
A recently completed international study has determined the typical service life and end-of-life (EOL) recapture rates (diversion from landfills) for common stainless steel applications. The researchers at the Center for Industrial Ecology at Yale University in New Haven, CT and the National Institute for Environmental Studies in Tsukuba, Japan estimated that 92% of stainless steel used in building and construction is collected for recycling at the end of life. Their article published in Environmental Science & Technology (insert link – this pdf was emailed) provides details on this and other end-use markets.
Bioclimatic architecture can substantially reduce building energy requirements. Buildings and spaces (interior and exterior) are designed using local climatic conditions to improve thermal and visual comfort. This approach can provide protection from summer sun, reduce winter heat loss, and makes use of the environment (e.g. sun, air, wind, vegetation, water, soil, and sky) for building heating, cooling, and lighting. The Construct Canada article Designing With Stainless Steel: Bioclimatic Hybrid Facades, shows how stainless steel is being used for innovative, award-winning, bioclimatic double facade projects around the world because of its longevity and low maintenance requirements. Additional information about Australia's award winning Green Star project Council House 2 can be found in the article Vertical Landscaping Ecologically Sustainable Stainless Design.