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The U.S. Green Building Council has rolled out the latest changes to its widely accepted Leadership in Energy and Environmental Design (LEED) green rating system. The changes, known as LEED v4, have increased the stringency of the requirements to comply with the principles of green design. By their very nature, some products are more conducive than others to compliance with the changes in LEED v4. This course will discuss masonry in terms of its inherent ability to meet and exceed requirements of the new model. Also discussed will be several high-performance masonry systems and how they meet energy targets, reduce noise, and meet aesthetic objectives.
In fall 2013, the U.S. Green Building Council formally launched changes to its green rating system. The result is LEED v4. While the system is currently in the transition stage, in which projects can earn credits under either the previous version, LEED 2009, or LEED v4, after October 31, 2016, all new building projects must register under LEED v4.
It is widely acknowledged that LEED v4 has increased the stringency of requirements across all sectors from water to energy to materials. LEED v4 also goes deeper into getting a real take on exactly what comprises a building project and, to that end, has introduced a new approach for building materials and products. With overarching goals of transparency, responsible sourcing, and rigorous documentation, LEED v4 asks some basics about building materials. What are they composed of, and are hazardous ingredients involved? Where are the materials sourced, and how do they come to the manufacturer? Can the manufacturer document the life-cycle impacts of its products? The most significant changes in LEED v4, in fact, occurred in the Materials and Resources category, with three entirely new credits focused on product disclosure.
For specifiers of building products in vertical construction projects, Materials and Resources is almost overwhelmingly the primary category in which products can contribute to credits, and the upshot for architects specifying those products is the need for more—and more diligent—product research. Architects will require more information and have more to consider when making product selections. Under LEED v4, the selection of a certain building material does not automatically earn a credit but may contribute, along with a host of other factors, to a specific credit. Those materials with environmental product declarations (EPDs) or health product declarations (HPDs) may be at an advantage as compared to similarly performing products, but it is up to the architect not only to determine the type of product which best suits the project needs, but also which manufacturer has the documentation for which products.
Though recycled content and regionally manufactured materials are handled differently in LEED v4 as compared to LEED 2009, those attributes can still be an important consideration when selecting building products. LEED also encourages the synergy that occurs when one product has multiple benefits or can serve multiple functions.
By its very nature, masonry makes for green building. Primary ingredients in masonry products—sand and other aggregates, and water—are plentiful and readily available. Recycled materials, such as post-consumer glass, slag cement, or recycled aggregate, are often used. Products are manufactured at numerous facilities located throughout the United States and Canada, with raw materials often locally sourced.
Masonry products also get high marks in energy efficiency. Materials such as insulation that have a high R-value are usually associated with greater energy efficiency. However, this is not the entire picture as it neglects the benefit of thermal mass, which is a measure of a material’s capacity to store heat for future distribution. Because they are high in mass, masonry walls offer excellent thermal performance. Their slow rate of heat transfer keeps interiors warm in winters and cool in summers. When used with complementary products or systems, concrete masonry units (CMUs) are particularly energy efficient. The mass of a masonry building also pays off in preventing easy sound transmission, reducing noise pollution, and helping to achieve a quiet environment—a feature much sought after in public buildings that accommodate large numbers of people. Using masonry can also lead to savings on insurance and maintenance costs as the material won’t burn, dent, rot, rust, or suffer insect infestation.
Many of these attributes may give masonry products an edge over other structural materials not only in sustainable building but also in actually contributing to LEED v4 credits. Many masonry products can contribute to various LEED v4 credits, not only meeting but exceeding requirements. Specific applicability will be discussed below.
As mentioned above, the category of Materials and Resources (MR) is the one to watch for potential credits earned by building materials. The heavily revamped credit class applies life-cycle thinking at the whole-building and product level, with credits earned for maximum material reuse and a design that ultimately has a lower impact on the environment. In LEED 2009, the Materials and Resources category awarded points in credits focused on the attributes of recycled content, regional materials, rapidly renewable materials, and certified wood, as well as reuse of materials and construction waste management. LEED v4 takes an entirely different approach. The focus of MR in LEED v4 is on product transparency. Six of the 13 possible MR points relate to product ingredient disclosure, including EPDs, supply chain reporting, and material ingredient reporting. Other significant changes in the MR category include the addition of whole-building life-cycle assessment and the elimination of regional materials as a standalone credit. The credits that form the MR category in LEED v4 are shown in Table 1. Credits relevant to masonry products are detailed in the following paragraphs.
Building Product Disclosure and Optimization—Environmental Product Declarations (EPD). This MR credit asks manufacturers to verify a specific product’s life-cycle effects, with an EPD representing the best path to credit achievement. Similar to nutrition labels on food products, EPDs document impacts generally from raw material to manufacturer. One point can be earned if at least 20 different permanently installed products that have EPDs are used. Accordingly, a masonry or other product for which the manufacturer has developed an EPD can contribute to credit achievement. Not all EPDs are created equal, however. Productspecific, ISO-rated EPDs will earn full-credit value, while generic industry-wide EPDs will only receive half-credit value.
Building Product Disclosure and Optimization—Sourcing of Materials. Option 2: Leadership Extraction Practices awards one point if at least 25 percent by cost of the total value of permanently installed products on the project meet at least one of the responsible extraction criteria. Responsible extraction criteria include the use of recycled content materials and the use of salvaged materials. It is important to check the recycled content of a product or contact the manufacturing facility, which may have the ability to add recycled content to other CMUs.
Building Product Disclosure and Optimization—Material Ingredients. Option 1: Material Ingredient Reporting awards one point if at least 20 different permanently installed products report chemical inventory of the product to at least 0.1 percent (1,000 ppm). Reporting options include using Chemical Abstracts Service Registry Numbers (CASRN), health product declaration (HPD), or cradle-to-cradle certification. In the masonry industry, manufacturers are in the process of publishing HPDs for their products.
Construction Waste Management. Projects can earn up to two points in this credit for either diversion of waste or minimization of total construction waste on the project. Many masonry products are recyclable. Further, use of these products minimizes construction waste on-site because their modular nature minimizes on-site cutting. Wood structural products may not fare as well here as the sheathing and plywood required in a wood-framed structure can result in waste at the construction site.
Optimizing Energy Performance. This credit, worth up to 18 points, awards points for reduction in building energy use as compared with baseline requirements based on ASHRAE Standard 90.1-2010. All concrete masonry can contribute toward an energy-efficient building shell, especially those that include integration of insulation. The benefits of thermal mass provided by concrete masonry include moderation of indoor temperature swings and delayed heat transfer. Insulated concrete masonry units provide an added advantage in meeting energy-efficiency goals. Systems that use molded insulation inserts can provide up to a 16.2 R-value, and foam panel systems provide a 9.2 R-value. Particularly, masonry systems where the insulation is part of the product may have an advantage over wood framing simply because in the latter, insulation materials must be added, increasing construction time and the potential for error.
Low-Emitting Materials. This credit, worth up to three points, focuses on volatile organic compound (VOC) emissions. This credit requires that 100 percent of the ceiling and wall materials used meet general emissions evaluation criteria to be considered a compliant category. Stone, glass, concrete, and clay brick are listed as “…inherently non-emitting and comply without any testing if they do not include integral organic-based surface coatings, binders, or sealants.” Most masonry products do not include integral organic-based coatings, binders, or sealants. It is important to note that factory-applied coatings must meet the California Department of Public Health Standard Method v1.1-2010 requirements to comply with this credit.
For Healthcare and Schools only, exterior applied products are required to comply with the VOC criteria if this credit is pursued. Masonry products without added coatings used in this application will generally comply with this requirement.
Acoustic Performance. LEED v4 for New Construction now includes a credit for acoustic performance. A credit for acoustic performance was previously only found in the LEED for Schools rating system. This credit includes sound transmission class (STC) requirements for interior walls ranging from 45 to 60 depending on the occupancy of adjacent rooms. An STC of 50 is required between hallways and adjacent rooms. Typical STC values for standard concrete masonry units range from 45 for a lightweight 8-inch unit to more than 60 for a fully grouted 12-inch unit. Some masonry wall systems have an STC of 61 or more, with certain specially designed acoustical masonry units providing sound absorption at all frequencies—even low frequencies that can be hard to control. Acoustics is clearly one area where masonry building products will have an advantage over wood or steel materials.
The LEED Rating System also includes credits for Innovation and Regional Priority. Innovation credits vary from project to project but typically include strategies not covered in LEED, LEED Pilot Credits, or going beyond the LEED requirements. Regional priority credits give added weight of up to four points to credits identified by USGBC’s regional councils and chapters. In many areas of the country, Sustainable Sites credits related to rainwater management and heat island effects are identified as regional priority credits. Another area where masonry products may be able to contribute is the LEED Pilot credits for Resilient Design. One point is earned for each credit met in the areas of: assessment and planning for resilience, design for enhanced resilience, and passive survivability and functionality during emergencies. These credits recognize projects that are planned and designed to function and/or quickly return to normal operation after extreme events or disasters, either natural or manmade. Masonry’s advantages here include noncombustibility, impact resistance, and ability to withstand flooding or other water damage without developing mold or other moisture-related problems. Masonry’s thermal mass also enhances passive survivability and functionality.Back