The key to thermal mass solutions
Sustainable masonry solutions
One of the biggest challenges for facility managers is operating a building for which decisions already have been made during the design phase. Yet, there is good news as more building owners and facility managers become part of the integrated design team and help guide the long-term operation of a building.
Today, facility managers are involved in helping to direct operational outcomes during the design phase. This results in a positive return for both the design team and the building owner’s team. To address both initial design and long-term operating and sustainability goals, masonry systems offer a variety of options.
While masonry’s assets have always included durability, low maintenance, and good indoor air quality, the greatest sustainability benefits are being found in masonry’s tie to enhancing energy efficiency. The choice of masonry for design and operating solutions comes from looking beyond the material as a finish selection and, instead, matching masonry systems to the building’s functional needs and sustainable outcomes.
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, both initially and in long-term operating costs. Passive measures are paid for one time; yet, when designed and constructed correctly, perform repeatedly over the life of the building.
Masonry systems, with the ability to enhance a building’s thermal performance, provide one of the best passive design options, resulting in an integrated passive design strategy that balances building performance with heating and air conditioning requirements.
Yale’s Kroon HallMasonry systems and materials helped Yale pursue LEED (Leadership in Energy and Environmental Design) Platinum for the School of Forestry and Environmental Studies’ Kroon Hall. 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. Chosen as a 2010 AIA/COTE Top Ten Green Project, the building provides light and openness, while taking advantage of masonry thermal mass solutions.
The exterior wall system, which contributed to the project’s “Platinum” LEED goal, included a two-inch air and drainage space, four 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 of around 8, while the Rockwool insulation made of 100 percent recycled material has an R-value of 16.8.
“We evaluated multiple options for the wall assembly,” says James A. Coan, AIA, LEED AP from Centerbrook Architects & Planners LLP, “and all options included [Rockwool] at the veneer cavity.”
And how is the building working today?
“The building is aging gracefully and performing as expected,” says Coan. “The use of thermal mass was a fundamental concept considered in the design of this building and contributes to the building’s higher level of energy performance with a lower level of air distribution.”
Centerbrook continues to use these principals of thermal mass design on current projects.
The most important, cost-effective design measures come from looking at the building envelope and marrying the building envelope to local geography, weather patterns and site options. That is particularly true regarding the U.S. Green Building Council’s (USGBC) LEED, which measures a building’s performance in terms of energy.
For the building envelope, green building performance is based on five concepts:
- Thermal resistance
- Thermal mass
- Air infiltration and exfiltration
- Moisture penetration
- Sustainable details and durable materials.
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. Constructability also results in optimizing costs for the owner.
Saint Joseph’s UniversityWhen Saint Joseph’s University in Philadelphia was faced with meeting the residential needs of its student body, the school turned to a structural masonry solution that, in addition to providing durability, fire-safety and aesthetics, resulted in the best monetary investment for the university’s projected budget.
Villiger Hall, a six-story residence hall by PZS Architects and J. Barbato Associates, utilized a fully grouted structural masonry system that includes a stone veneer exterior, two inches of rigid insulation, and a full drainage board design. Supported by nine out of 10 cost studies, the cost of loadbearing masonry was determined to be less expensive than providing the university with a steel-framed building.
And, if upfront construction savings are not enough, Villiger Hall should expect to benefit from thermal mass efficiencies that occur due to the placement of thermal mass – loadbearing exterior and interior partitions – located throughout the building.
The ins and outs of green masonryMasonry materials are excellent materials for both interior and exterior applications. In addition to having excellent thermal mass qualities, which aids in absorbing excess temperatures, masonry materials are durable, and easily cleaned and maintained. Concrete block now can be found with a variety of textures and colors, and is becoming a material of choice for corridor walls, gymnasiums, libraries 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 envelopes 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.
Children’s Hospital of Pittsburgh of UPMCFor 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-square-foot 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 VP - healthcare.
“Using masonry and other unitized material allows designers to create patterns and surface effects that no other materials can do,” says Powers, noting this was particularly true for this urban campus. “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 provides a thermal mass strategy with low maintenance cost, while assisting in earning LEED points for local or recycled components.
A new look at old materialsOne commendable facet of the green race is how it inspires designers and contractors to look anew at old materials or existing buildings.
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. Drainage pavers are providing solutions for a variety of stormwater management concerns faced by facilities managers balancing campus environments, as well as city planners balancing community development issues.
Green retrofit projects are finding that the most optimal solution to upgrading existing masonry buildings is to allow masonry to be in clear view of the occupant. Designers are recognizing the added value that existing masonry inboard of the building’s insulated envelope offer. Instead of hiding masonry with additional materials, retrofit projects in both the United States and Canada are choosing to repair and expose brick walls, stone surfaces and tile and terrazzo floors to take advantage of their thermal mass contributions.
Guidelines and workmanshipGuidelines for sustainable construction have expanded over the years and now include code requirements, policies and municipally supported standards. We are seeing a growing trend in recording the performance of buildings, both as a measure of information sharing and quality control. Building commissioning now has expanded to include the review of the building envelope. Building envelope commissioning already is showing up in public and private projects and covers all design and construction phases of a project. As standards increase, quality of construction becomes ever more important.
With a masonry envelope that provides shelter and energy performance, quality assurance guidelines are critical. The International Masonry Institute (IMI) supports the industry by partnering with the full design and construction team to deliver a quality masonry project. To assure the design intent and project quality, IMI administers training for union craftworkers in all trowel trades, and uniquely supports the continuing education for journeyman and foremen on all building envelope components that added to the overall performance of a masonry building. IMI also provides contractor education including LEED compliance certification under IMI’s Sustainable Masonry Certification Program (SMCP), the only contractor program registered with USGBC.
About the Author
Maria Viteri, AIA, is Director of Program Development for the International Masonry Institute, and Project Coordinator for Masonry Variations.