LEED v4 and Masonry

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.

Masonry products are already engineered to fulfill the requirements of LEED v4.

LEED Credit: Materials and Resources

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 stand-alone 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. Product-specific, 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.

LEED Credit: Energy and Atmosphere

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.

SOUTH CAROLINA HIGH SCHOOL OPTS FOR MASONRY VENEER

Faced with a need to manage the area's continued growth, Richland School District Two put together a 10-year master plan that included the construction of this new state-of-the art educational facility that opened its doors to 1,700 students in 9th–12th grade in the fall of 2012. Masonry veneer was selected to clad the exterior of the 340,000-square-foot facility, as well as wrap a number of interior columns. Architects AAG Associates LLC of Beaufort, South Carolina, chose the product for its look of natural stone without the high cost. In addition, the ability to manufacture the product at a regional facility with a percentage of recycled concrete offered additional LEED consideration. The placement grid provided by the insulated panels has increased overall construction speed and virtually eliminated what lead architect Chris Caudle calls the "oops" factor. "The installation is faster and cleaner than I expected," says Caudle. "The contractor needs to take care in the initial layout of the first few insulation panels, and it almost guides itself from there."

Masonry veneer was chosen for its look of natural stone without the high cost.