Photo courtesy Super Stud Building Products
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. |
