Using steel in LEED v4 projects

by Katie Daniel | January 31, 2018 10:08 am

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by Mark A. Thimons, PE, LEED AP
Steel has long been recognized for its strength, durability, and functionality. More recently, it is being noted for additional advantages in sustainability, particularly its high recycled content and end-of-life recovery rate. When used in construction, the material contains between 25 and 100 percent recycled content, is nontoxic and noncombustible, and creates minimal waste during production. it is also 100 percent reusable or recyclable at end of life with no loss in performance.

This last point is particularly important, as the ability for future generations to reuse steel products over and over defines its sustainability. Since 1990, the amount of energy needed to produce a ton of steel in North America has decreased by 31 percent and associated carbon dioxide (CO₂) emissions have also reduced by 36 percent, with some even greater improvements expected in the future.

Over the years, sustainable design standards and green building rating systems like the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) program have helped construction professionals demonstrate the sustainability of their building projects. The use of steel construction products can assist in the meeting of the LEED certification requirements, helping earn points for projects in a range of credits.

In 1998, LEED was introduced to help professionals design, construct, and operate buildings in more sustainable and efficient ways. Currently, 3.4 million m² (3.6 billion sf) of North American real estate is LEED-certified. In 2015, the green building growth rate hit 13.2 percent, and the industry is still a $120- to $145-billion market growth opportunity.

As energy efficiency and sustainability have both become more common, LEED and green building have evolved from a set of aspirations to being the marketplace standard. The program is referenced in planned building project specifications for nearly 71 percent of projects over $50 million, making it vital for construction professionals to remain up to date with its latest developments and requirements. ( This is according to a 2011 report by Harvey M. Bernstein, F.ASCE, LEED AP, called “The Green Outlook 2011: Green Trends Driving Growth through 2015.” For the full report, visit www.ecocosminc.com/img/2011_McGraw_Hill_Green_Outlook.pdf[2].)

New additions in LEED v4
The rapidly evolving green building industry and increasing demand for environmental sustainability have led to updates, improvements, and also a more rigorous LEED certification process. The development of its latest iteration, LEED v4, spanned more than three years, engaging hundreds of volunteers and thousands of stakeholders worldwide.

The updates to LEED increase the focus on materials and resource transparency. Building professionals must understand how material decisions could affect
the project review and certification process. Steel-intensive building designs can be a significant contributor to earning points for a variety of LEED v4 credits. They may also provide builders with an immediate advantage because of the North American steel industry’s transparent supply chain and wealth of available life cycle inventory (LCI) data for all steel products.

The health and well-being of building occupants also factor into LEED v4. Human health credits are new to the rating system and can be achieved through a variety of documentation practices, including Health Product Declarations (HPDs) and Material Health Certificates. These documents examine the potential human health impacts of products used in building construction, providing a comprehensive view of the contents of a product and their potential health hazards. These declarations deliver increased transparency by helping construction professionals accurately assess and also compare product health characteristics.

In the interest of improving its rating system methods, LEED v4 places an increased focus on life cycle assessment (LCA), environmental product declarations, and improved product transparency. Understanding no two projects are the same, LEED v4 features greater flexibility for different market sectors, as well as a more streamlined documentation process with better alignment between rating systems.

TRANSPARENCY IN THE NORTH AMERICAN STEEL INDUSTRY

The North American steel industry provides resources to help building professionals earn certification under the Leadership in Energy and Environmental Design (LEED v4) program. In particular, the industry has been working to develop a complete list of available Environmental Product Declarations (EPDs) for steel building products. These EPDs are more comprehensive than those for some other building materials, creating an all-encompassing view of each product’s environmental impacts.* Currently, EPDs are available in the following product categories for use in North America: cold-formed steel studs and track—Steel Recycling Institute (SRI); open-web steel joists—Steel Joist Institute (SJI); steel roof and floor decks—Steel Deck Institute (SDI); roll-formed steel panels (Canada)—Canadian Sheet Steel Building Institute (CSSBI); roll-formed steel panels for roofs and walls—Metal Construction Association (MCA); insulated metal panels (IMPs)—MCA; fabricated steel plate—American Institute of Steel Construction (AISC); fabricated hot-rolled structural sections—AISC; primary structural steel frame components—Metal Building Manufacturers Association (MBMA); secondary structural steel frame components—MBMA; roll-formed metal wall and roof panels—MBMA; fabricated hollow structural sections—AISC and Steel Tube Institute (STI); hot-dip galvanized steel after fabrication: galvanized hot-rolled sections, plate, and hollow structural sections—American Galvanizers Association (AGA); hollow structural steel (HSS) sections—STI; fabricated structural steel plates (painted)—Canadian Institute of Steel Construction (CISC); fabricated structural steel plates (unpainted)—CISC; fabricated HSS sections (painted)—CISC; fabricated HSS sections (unpainted)—CISC; fabricated hot-rolled structural steel sections (painted)—CISC; and fabricated hot-rolled structural steel sections (unpainted)—CISC. * More information on steel product EPDs and updates on their sustainability resources can be found at www.buildusingsteel.org/EPDs[3].

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Using steel to achieve LEED v4 certification
Steel has always been positioned for credits in categories such as recycled content, but LEED v4 offers more opportunities for the material to help earn credits across a range of categories.

Materials and Resources (MR) credits
The MR category focuses on minimizing the embodied energy, emissions, and other impacts associated with the extraction, processing, transport, maintenance, and disposal of building materials. The requirements are designed to support a life cycle approach, which improves performance and promotes resource efficiency. It is this category where steel-intensive design truly excels within LEED v4 requirements and can contribute to a variety of credits.

Industry-wide and product-specific environmental product declarations for several North American steel construction materials have been completed or are nearing completion. Simply providing an Environmental Product Declaration (EPD) for at least 20 different permanently installed products sourced from at least five different manufacturers will earn credit for the disclosure portion of the Building Product Disclosures and Optimization–EPD under LEED v4.

Due to their high recycled material content, steel structures and components are valuable for builders seeking Building Product Disclosures and Optimization–Sourcing of Raw Materials credits. Steel is the only building material recognized by LEED as having a default value of 25 percent post-consumer recycled content. Product-specific documentation of recycled content in steel products may be as high as 100 percent for some products, such as structural sections and reinforcing bars.

For each of the Building Product Disclosures and Optimization categories, disclosure involves providing documentation about some of the building material products used in a project. Optimization involves assurance a percentage of building products complies with environmentally positive characteristics identified in LEED v4.

Due to its offsite fabrication, steel generates very little construction waste. Additionally, steel scrap is typically reused or recycled. Any steel generated from demolition can easily be repurposed, greatly assisting with obtaining the Construction and Demolition Waste Management credit.

Credits for Building Life Cycle Impact Reduction and Design for Flexibility focus on a building’s potential to be modified to meet changing needs throughout its lifetime. Steel buildings are adaptable and suitable for reuse. Bolted and screwed connections can be easily disassembled and repurposed, while welded members can be cut without either compromising the material or limiting its abilities. Cold-formed steel partitions can be removed, reused, and/or relocated as part of a building modification. Structural steel framing could easily be modified for changes in loading requirements and/or alterations to intended use or occupancy.

Steel typically emits no volatile organic compounds (VOCs) once installed in a building, and most steel-based furnishings are very capable of meeting the minimal chemical content requirements of the Furniture and Medical Furnishings credit that only applies to healthcare structures.

STEEL ROOFING SYSTEMS FOR WARMER CLIMATES

According to a 2013 report entitled “Sustainable Energy in Building Systems” by D. Paul Mehta, PhD, and Martin Wiesehan, buildings consume two-thirds of all electricity and one-third of all energy produced in North America. The roof can have the greatest impact on the energy use of a building. Energy Star reports lightly colored, more reflective roofs can reduce the amount of air-conditioning needed in buildings and reduce peak cooling demand by 10 to 15 percent. While it is recognized adding insulation under the roof surface can reduce cooling and heating costs, there is a diminishing return on the strategy of increasing insulation to conserve energy costs. This is where ‘cool roofing’ can play a role in large urban areas by way of reducing consumed energy and minimizing the heat island effect. Steel roofing materials are available in various finishes, colors, textures, and roofing profiles. They offer varying levels of reflectivity and emissivity, fitting building needs in a wide range of regions and climates. Reflectivity refers to a roof’s ability to reflect solar radiation back into the atmosphere, preventing it from being absorbed into the building envelope and, in turn, reducing the need for energy to cool the building. Emissivity is the ability to emit absorbed solar infrared radiation back to the atmosphere. Cool metal roofs also help increase the energy efficiency of steel-framed buildings in warm climates. Calculations involving solar reflectance and emittance can be used to determine the energy savings attributable to a roof. Steel roofing can reduce energy costs associated with air conditioning. For cooling loads, it is advantageous to both reflect solar radiation and re-emit as much of the absorbed infrared radiation as possible. A high solar reflectance is the most important characteristic of a cool roof, as this helps reflect sunlight and heat away from the building, reducing roof temperatures. A high thermal emittance also plays a role, particularly in climates that are warm and sunny. Together, these properties help roofs to absorb less heat and stay up to 28 to 33 C (50 to 60 F) cooler than conventional materials during peak summer weather. In addition to energy-saving benefits, steel roofs can contribute to a building’s use of renewable energy. They provide the optimal foundation for photovoltaic (PV) installations since the roof can be expected to last longer than the PV system it supports. When it is ultimately removed during building demolition or renovations, any steel used in metal roofing is fully recyclable, allowing it to credibly claim both a high level of recycled content and 100 percent recyclability by recognized definitions. The product’s recyclability also provides significant savings on construction removal and disposal costs. Steel roofing systems that are chosen for school, government, commercial, and industrial buildings are available in a number of stock sizes and finishes, and can be customized to satisfy the requirements on both simple and highly complex projects. Due to their light weight, steel roofs can provide structural savings in buildings when compared with heavier nonmetal roofing alternatives. For reroofing projects, steel roofing can often be applied on top of a nonmetal roof, saving removal and disposal costs. These assemblies also provide significant advantages in reduced energy use and overall sustainability. More information on both steel roofing products and local contractors can be found on the Metal Roofing Alliance website at www.metalroofing.com[5].

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Energy and Atmosphere (EA) credits
The EA category in LEED v4 approaches energy from a holistic perspective, addressing energy use reduction, energy-efficient design strategies, and also renewable energy sources. Due to its dimensional stability, steel framing can contribute indirectly to the Optimize Energy Performance credit. Properly designed steel framing can provide an exceptionally tight building envelope, resulting in reduced air loss and better building energy performance over time.

Steel roofs offer an excellent platform for solar photovoltaic (PV) systems because of their long expected lifespans, which can meet or even exceed the 20- to 30-year expected lives of solar PV panels. These roofs can help designers attain points through the Renewable Energy Production credit. Additionally, proprietary connection and framing systems are available to mount PV panels directly to standing seams of steel roofing panels, eliminating the need for attachments that penetrate the roof.

Sustainable Sites (SS) credits
The SS category rewards decisions about the environment surrounding a building, with credits to emphasize vital relationships among buildings, ecosystems, and ecosystem services. The category focuses on restoring project site elements, integrating the site with local and regional ecosystems, and preserving the biodiversity on which natural systems rely.

Steel-intensive design can support multiple credits within this LEED v4 category. Since most of the steel structures and components are manufactured offsite, construction time and the likelihood of site disturbances are reduced, contributing to earning the Site Development–Protect or Restore Habitat credit. Additionally, many available steel sheet roofing products meet the Solar Reflectance Index (SRI) criteria in relation to the Heat Island Reduction credit, which results in reduced cooling loads and lower utility bills. Some of these products utilize reflective pigment technology, allowing for a wider range of colors that meet LEED v4 requirements.

The future of sustainability in the steel industry
As green building requirements continue to develop, the steel industry is expanding its efforts to improve both sustainability and transparency. At this time, some construction product manufacturers are working to develop HPDs, which are intended to provide a transparent path to determine the contents of products and their related health hazards, as well as reward building professionals additional credits within the LEED v4 rating system.

The North American steel industry is also working to refresh LCI data to keep its EPDs and life cycle assessment materials up to date with the latest industry innovations. Additionally, the industry is developing whole-building LCA comparisons that show the potential environmental impact of different construction materials in functionally equivalent buildings. These projects demonstrate the comprehensive environmental impacts across a variety of scenarios and climates, from raw material extraction to the end of a building.

Design/construction professionals, building owners, and the general public are becoming increasingly aware of the need to consider sustainability principles. An increased knowledge and understanding of the environmental impacts of building materials will lead to the construction of truly sustainable structures. As design professionals witness the impact of this increased demand, they will also experience continued improvement in tools to demonstrate how materials and products affect the environment in sustainable steel buildings.

CASE STUDY: KLARMAN HALL, HARVARD BUSINESS SCHOOL

[7] Designed by Boston-based firm William Rawn and Associates, Harvard Business School’s Klarman Hall will serve as a main gathering point for the global intellectual community in Boston. On completion, the facility will house a large-scale conference center as well as a performance and creative gathering space. State-of-the-art digital technology, multipurpose space, and the flexibility to accommodate up to 1000 guests are just some of the targeted key features in this $97.5-million project. Harvard broke ground on the project in April 2016 and construction is expected to be finalized this fall. Another key component of Klarman Hall is environmental sustainability. The project team is working to develop the building to earn Gold or higher certification under the new LEED v4 program.

 

Mark A. Thimons, PE, LEED AP, is the vice-president of sustainability for the Steel Market Development Institute (SMDI), a business unit of the American Iron and Steel Institute (AISI). He is responsible for overseeing the Steel Recycling Institute (SRI), as well as research projects demonstrating the life cycle advantages of steel in the construction, automotive, and container markets. Thimons can be reached via e-mail at mthimons@steel.org[8].

Source URL: https://www.constructionspecifier.com/using-steel-leed-v4-projects/

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