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High-Performance Envelopes Demand Know-How Architectural Record WE demand a great deal from the building envelope—the skin that shelters us from the outside world. For starters, it must protect us from ram and snow, provide appropriate amounts of sunlight and fresh air, retain interior warmth m the winter and resist exterior heat in the summer, all the while exuding an aesthetic that suits owner and public alike. To this intricate mix, add the tantalizing promises of new materials, products, and systems, and ever more stringent energy, security, and other requirements, and the j ob of designing a building's outer shell becomes very complicated indeed. So complicated, in fact, that some fear architects may be losing their grip on this most visible building component "The exterior of the building is how architects identify ourselves—it's our calling card, yet we are no longer in control of it if we don't know the building science and the technology necessary to design high-performing envelopes," says Richard Keleher, AIA, a technical-quality and drawing-review consultant in Concord, Massachusetts, and former director of building-envelope technology at The Stubbins Associates. He predicts that, if things continue as they have in recent years, envelope consultants may one day be dictating the look of our buildings. Fortunately, three recent national efforts to improve the performance of building envelopes are laudable steps toward remedying the current situation. These include the publication of the Building Envelope Design Guide, a comprehensive resource for the design and construction of institutional and office buildings; the Exterior Enclosure Technical Requirements for the Commissioning Process, which outlines a step-by-step process to ensure that a new envelope will function as intended; and the formation of building enclosure councils, which establish a forum within which practicing architects throughout the country can begin to learn the fundamentals of building science and discover regionally appropriate solutions. Although all three efforts evolved separately, the complementary programs have coalesced under the auspices of the National Institute of Building Sciences (NIBS), in Washington, D.C., a nonprofit, nongovernmental organization established by the U.S. Congress in 1974 to serve as a bridge between government and the private sector in order to improve the quality and efficiency of construction in this country. Among many other functions, NIBS disseminates technical information and helps introduce appropriate technologies into the building process. Referring to the advancement of high-performance envelopes, NIBS vice president Earle W. Kennett observes, "No one discipline figures this into their domain because of the multidisciplinary nature of the work." Nonetheless, to achieve high-quality enclosures, it is critical that the different disciplines interact and learn from each other. As an experienced intermediary among the varied facets of the design and construction industry, XIBS was well positioned to take on these new, inherently multidisciplinary initiatives. Design and construction guidelines The Building Envelope Design Guide is being produced by NIBS to provide comprehensive guidance on the design and construction of high-quality, long-lasting enclosures for offices and other public buildings, such as courthouses and hospitals, under the purview of six federal agencies: the Army Corps of Engineers, the Naval Facilities Engineering Command (NAVFAC), the Air Force, the General Services Administration (GSA), the Department of Energy, and the Federal Emergency Management Agency, [t is the first time ever that a group of federal agencies have joined forces to develop and rely on a single set of design and construction guidelines. Although intended to improve the performance of building envelopes within the public sector, the guide promises to be a great resource for architects and building owners within the private sector as well. The guide will be a Web-based rather than hard-copy document so that it can be more easily accessed and searched by users and expanded and updated on an ongoing basis by NIBS. It will be one of a series of guides posted on a relatively new Web site called the Whole Building Design Guide (www.wbdg.org), which is provided by NIBS, with support from the NAVFAC Criteria Office, GSA, the Department of Energy's National Renewable Energy Laboratory, and the Sustainable Buildings Industry Council, to facilitate the dissemination of regulatory and technical information to the building community. The first version of the Whole Building Design Guide will be available, free of charge, on the WBDG Web site later this year. The new guide builds upon an earlier one, called Envelope Design Guidelines for Federal Office Buildings: Thermal Integrity and Airtightness, which was developed for GSA by Andrew K. Persily of the National Institute of Standards and published in 1994. "The earlier guidelines are being rounded out, filled in, and updated," explains Wagdy Anis, AIA, director of technical resources at Shepley Bulfinch Richardson and Abbott, m Boston, and chair of the Building Environment and Thermal Envelope Council (BETEC), a long-standing NIBS committee whose mission is to encourage optimum energy use of buildings through a better understanding of how overall, complex building components interact with each other and with the environment. The new guide consists of an introduction plus five chapters on below-grade construction (including the basement walls, foundation, and floor slab that divide the interior from the exterior environment); structural and nonstructural exterior walls; low- and steep-slope roofing; fenestration (windows and curtain walls); and atria. Discussions of each system will include a basic description; fundamental principles of design; appropriateness of applications in terms of building function and climatic conditions; generic construction details in CAD format with extensive explanatory notes; a survey of significant current research and development; a summary of applicable codes and standards; and additional resources. Each system will be examined in terms of material durability, maintenance, thermal performance, moisture protection, fire safety, acoustics, and—in the case of fenestration and atria—daylighting and visual qualities. In addition, the connections between any nonstructural components of the enclosure and the building structure will be addressed. An accompanying series of papers will discuss sustainability; indoor air quality and mold prevention; HVAC integration; and the following safety issues: extreme wind; seismic activity; flood; blast attacks; and chemical, biological, and radiation (CBR) attacks. Exterior enclosure commissioning process Meanwhile, on another front, NIBS is in the process of preparing a building envelope commission guideline to be called NIBS Guideline 3-2005:Exterior Enclosure Technical Requirements for the Commissioning Process. This publication builds on—and is to be used in conjunction with—ASHRAE/NIBS Guideline 0-2005: The Commissioning Process. Guideline 0-2005, which outlines—without reference to a specific discipline—the basic procedures in the commissioning of any building component within a new or renovated project, was just approved in January by the ASHRAE board. A total of 14 guidelines, in addition to Guideline 0-2005, are anticipated to address the gamut of systems to be considered in a total building commissioning program.
Building commissioning is a systematic process of quality control through the predesign, design,
construction, occupancy, and operations
phases to assure that the owner gets a building that functions as intended. "The intent is to prevent errors
before they occur," says Joseph J.
Deringer, AIA, president of The Deringer Group in Berkeley, California, and chair of the NIBS Enclosure
Commissioning Guideline Committee.
Historically, commissioning had focused on the start-up of the mechanical
system toward the end of the construction phase to assure that it was
running properly and efficiently before handing the keys over to the owner. But as greater
emphasis was placed on building performance as a whole, it became clear that
such a quality-assurance program had to start The body of the envelope commissioning guidelines will be general enough to address the basic process for all building types, sizes, functions, ownership structures, and delivery methods. To begin the process, for example, the owner or owner's representative should develop a comprehensive list of project requirements as early as possible in the building delivery process, preferably before design begins These requirements will take into account the inherent trade-offs between quality and cost The ASHRAE/NIBS guidelines call this the "Owner's Project Requirements," or OPR The design team, in turn, responds to the OPR with the "Basis of Design," or BOD In the case of the building envelope, the BOD typically includes a description of each exterior envelope system option considered, including subsystems, materials, and components, a description of the interaction of the building exterior enclosure system with other building systems, the reasoning for the selection of the final building exterior enclosure system, and documentation of related assumptions, calculations, codes, and standards that were used in this decision-making process. With the OPR and BOD established, the project team then proceeds according to a methodical and transparent series of checklists, peer reviews, mock-ups, in-situ testing, documentation, and staff training at appropriate stages in the process in order to avoid any miscommunication or misconceptions among the various parties Deringer emphasizes that these guidelines do not require an outside commissioning agent "It's okay if an architecture or engineering firm commissions its own projects, as long as the people who undertake the quality control work k are different from those who do the design. An attached series of annexes will provide specific tools, delve further into certain key topics, and discuss issues pertinent to particular building projects It is within the annexes that readers will be presented with actual case studies The proposed annexes include:
The Enclosure Commissioning Committee, which includes architects,
engineers, builders, scientists, and representatives from
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