BUILDING ENVELOPE
Sustainable Masonry Solutions:
The Envelope Please

One of the biggest challenges for facility managers is operating a building where decisions have already been made during the design phase. As long-term guardians of building performance, it makes sense to incorporate their responsibilities into the initial design solution, particularly when it comes to sustainable design. To address both initial design and long-term sustainability goals, masonry systems fit the bill.

While masonry’s sustainability assets include durability, low maintenance, energy efficiency and good indoor air quality, the greatest benefits come from looking beyond simple material selection, to overall outcomes.

Masonry materials and construction strategies helped Yale pursue LEED Platinum
for the School of Forestry and Environmental Studies’ Kroon Hall.

Sustainability outcomes are about managing resources, materials, site conditions, human comfort and energy. Particularly on the energy criteria, design solutions often neglect to incorporate passive measures that provide facility managers with the most value for money invested, measuring for both initial and long-term operating costs.

The most important cost-effective design measures come from looking at the building envelope. That is particularly true when it comes to the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED), which measures a building’s performance in terms of energy savings.

For the building envelope, green building performance is based on five concepts:
• Thermal resistance
• Thermal mass
• Air infiltration and exfiltration
• Moisture penetration
• Sustainable details

More than a single solution, such as insulation, the building envelope is an integrated component to be understood holistically. Systems include mass materials (e.g. brick, block, stone, tile, terrazzo), insulation, air barriers, vapor barriers, and flashing and weep materials. Each system uniquely contributes to one of the five building performance
concepts.

Grasping the entire system is the best way to anticipate and avoid problems. Constructability and proper detailing have a greater and more economical impact on energy performance than any operating system added later.

With a masonry envelope that provides shelter and energy performance, quality assurance guidelines are particularly important. Experienced masonry contractors work closely with the construction team.

The Ins and Outs of Green Masonry
Masonry can help in numerous LEED categories, for both new construction and restoration or renovation. The International Masonry Institute (IMI) LEED checklist addresses all masonry materials—brick, stone, tile, terrazzo, marble, plaster, and cement.

Masonry materials are excellent materials for both interior and exterior application. In addition to having excellent thermal mass qualities, which aids in absorbing excess temperatures, masonry materials are durable, easily cleaned and easily maintained. Concrete block can now be found with a variety of textures and colors and is becoming a material of choice for corridor walls, gymnasiums, library and multi-purpose spaces. In addition to having fire-resistant characteristics, block walls assist with noise reduction. Autoclaved Aerated Concrete (AAC) is an interesting lightweight block that provides superior fire-resistance and acoustical performance. The material is easy to cut and therefore, a perfect masonry material for walls that require electrical or plumbing chase space.

Material and system choices should be made to reinforce sustainable outcomes. To address energy costs, use brick, block or stone on exterior envelope or on interior walls for indirect solar gain. To maximize opportunities for good indoor air quality, use ceramic or stone tiles or stone panels on interior horizontal and vertical spaces.

For one of the nation’s top pediatric institutions, Children’s Hospital of Pittsburgh of UPMC, designers at Astorino used masonry as part of an environmentally sensitive design that also offers reduced operation costs. The ambitious project of renovation and new construction for the 1.4-million squarefoot campus covered inpatient and ambulatory care facilities, pediatric research, a healing garden, expanded central plant facilities, a data center, and parking and traffic improvements.

LEED strategies for the massive, $625 million project included material choices both outside and in. For the facade, where maintenance and long-term sustainability in the Pittsburgh climate was critical, Astorino chose masonry, because “it is very durable, easy to assembly and looks great for a lifetime,” says Timothy L Powers, AIA, senior vice president-healthcare.

“Using masonry and other unitized material allows designers to create patterns and surface effects that no other materials can do,” says Powers. That was particularly true for this urban campus, he notes. “We were situating a very large structure into a dense urban fabric, so we looked for similar, locally used materials, and used them in non-traditional applications. The design response is extremely successful.”

Inside, the 11,000-square feet of terrazzo for the research building, for example, earned points for local or recycled components, and a natural, no-wax finish that cuts down on maintenance costs. Other strategies included construction waste and site management, among many others.

For the Yale School of Forestry and Environmental Studies, there was no question that the new home for America’s first professional forestry program would be sustainable. It also had to blend well with the venerable campus while distinguishing itself through contemporary architecture.

The exterior wall system, which contributed to the project’s “Platinum” LEED goal, included a 2-inch air and drainage space, 4 inches of rockwool insulation, an air and moisture barrier, and eight inches of Autoclaved Aerated Concrete (AAC) masonry units. The AAC units carry an R-value around 8, while the rockwool insulation made of 100% recycled material has an R-value of 16.8.

“We evaluated multiple options for the walls,” says James A. Coan, AIA, LEED AP from Centerbrook Architects & Planners, LLP, “and all options included the (rockwool) at the veneer cavity.” Other LEED point contributors were exterior stone quarried within 500 miles of the campus, and “thermally inactive” concrete, plus recycling of construction waste and other contractor strategies. School officials proclaim it as “Yale’s greenest building” that serves as the cornerstone for the campus’ ambitious sustainable building efforts.

A New Look at Old Materials
One commendable facet of the green race is how it inspires designers and contractors to look anew at old materials.

Take humble brick pavers that “can offer more than aesthetic solutions,” notes William McConnell of Architectural Paving & Stone, Inc. He recommends a stroll around the campuses of Harvard and MIT, where brick pavers are being used extensively in both new and reconditioned buildings.

Instead of putting them on a traditional sand bed, they can be placed on pedestals or other setting systems to function as a radiant floor, collecting energy from the sun and transferring it to a below grade water system. When used on a roof deck or terrace, they also offer more usable space, plus easy maintenance. Drainage pavers designed specifically for streets, driveways and parking lots let water penetrate down into the subsoil, and help with both LEED and zoning issues.

The guiding principle is that, whenever it becomes part of a surface, or a divider between the outside and inside, masonry materials offer versatility. Its many forms, beginning with structural, are compatible with a variety of climates and are good environmental stewards. Many are found regionally and some, like stone, can be fabricated on site.

The latest version of LEED 2009 has 110 points. With masonry addressing the sustainable intents of 52 of them, you are halfway there.

Maria Viteri, AIA, LEED AP, is director of sustainability and program development for the International Masonry Institute (IMI). She is a board member with the Sustainable Buildings Industry Council (SBIC). She can be reached at mviteri@imiweb.org.
 

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