New Construction Peer Review Getting the Most out of Your Building Envelope Consultant
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I S S U E 4/2013 VOLUME 30 NUMBER 4 Journal of architectural technology published by Hoffmann Architects, Inc., specialists in the rehabilitation of building exteriors. New Construction Peer Review Getting the Most out of Your Building Envelope Consultant Craig A. Hargrove, AIA and Stephanie L. Dillon, Assoc. AIA With today’s strict energy conser- specialist can identify ways to reduce vation codes and increasingly com- costs with details that are watertight, plex facade and roof systems, many thermally insulating, and correctly new construction projects involve the constructed; when amplified over the services of a building envelope design entire building, even small improve- professional as part ments can add up to substantial sav- of the project team. ings. Ideally, boosting exterior envelope Making the best use performance can reduce the necessity of that consultant’s for larger mechanical packages and services is impor- mitigate the effect of energy-consum- tant not only to the ing systems, such as lighting. bottom line of the construction project, To realize these benefits, there are but to the energy steps a building owner or design ar- efficiency, code com- chitect can take to get the most value pliance, sustainability, from a building envelope consultant. integrity, and longev- The role of the envelope specialist ity of the building. changes throughout the design and When should a build- construction process, and knowing ing envelope con- when and how he or she should be sultant get involved involved can make a big difference to in a new construc- the project outcome. tion project? What Technical details, such as sealant joint design, make the difference services should he or Material and Assembly Specification between a long-lasting building and one that fails prematurely. she be expected to Because building envelope architects provide? How does and engineers work exclusively with the consultant’s role the outsides of buildings, they tend to differ from that of the architect of amass substantial knowledge of facade record? What, exactly, does a building and roof systems and their proper- envelope consultant do? ties. Therefore, when it comes time to By working with the design team to formulate and apply building envelope establish performance criteria for system criteria – whether budget- the building envelope, the consultant ary, ecological, performance, or design proposes materials and components – the envelope specialist brings key to optimize efficiency across facade background experience to the project and roof assemblies. The envelope team in establishing these parameters Craig Hargrove, AIA LEED AP, senior vice president of Hoffmann Architects, Inc., oversees the development of design solutions, both for new construction and for the rehabilitation of existing structures. Stephanie Dillon, Assoc. AIA, project manager, provides envelope consultation for building managers and design professionals. JOURNAL Curtain wall construction at this glass high-rise involved quality control of fabrication, assembly, installation, and field verification, to see that the final product meets design standards for performance and sustainability. and identifying options for suitable envelope design on the size and cost counts. That’s where building envelope envelope systems. of heating and cooling systems. consultants really pay for themselves: Recently, one of our engineers pro- As an example, consider fenestra- by specifying components individually, vided facade design consultation tion design. Energy loss tends to be rather than as a prefabricated system, services for a new residential high-rise greatest at the edges of glazing, where the envelope specialist can handpick in Manhattan. In a city where space is inefficiencies of the frame transfer only those parts that are essential, at a premium, a central consideration thermal load to the glass. By specifying thereby reducing costs on a piece-by- for any developer is how to maximize warm edge spacers – low-conductivity piece basis. interior floor space while meeting materials used in lieu of aluminum to A recent new construction project at design and performance requirements position the panes of insulating glazing a military base in New England pro- for the facade. After evaluating energy units (IGUs) – the envelope consultant vides an excellent example of design code requirements and probable con- can mitigate heat loss across windows collaboration between the architect struction costs, the engineer was able or glazed curtain walls. Even seemingly of record and the envelope specialist. to recommend a facade assembly that minor modifications like this one can With a very tight budget, the project met the relevant energy efficiency re- improve thermal performance enough was nonetheless expected to earn quirements, but which was shallow in to permit downsizing of mechanical LEED certification by using efficient, depth, thereby maximizing apartment equipment, often netting both short- well-designed envelope systems. Our square footage. and long-term savings. building envelope engineer ran ther- With energy code often the prime Green building projects can make mal computer models for a number directive driving design, balancing the most of the building envelope of different roof assemblies, then mechanical package efficiency with consultant by involving him or her provided options to the project team. building envelope thermal resistance in the design phase, to brainstorm In addition, we advised on the integra- has become a central consideration. In exterior wall and roof assemblies and tion of air and vapor barriers, particu- order to achieve the requisite energy to act as a sounding board for design larly at facade/roof intersections. By performance, design teams must offset decisions. Many government projects optimizing the configuration and type an economical mechanical package are now required to obtain certifica- of insulation in the roof assembly, we with strict control of heat transfer tion from Leadership in Energy and were able to assist the design architect across the building exterior. Working Environmental Design (LEED) or simi- in maximizing efficiency while reducing with the mechanical engineer, the lar rating systems. At the same time, construction costs. The project stayed envelope consultant provides options municipal, state, and federal budgets within budget and earned LEED Gold that consider the impact of exterior are stretched thin, and every dollar certification. (continued on page 4) 2 VOLUME 30 NUMBER 4 The Building Envelope Consultant’s Role The purpose of an exterior envelope specialist in a new mechanical system efficiency. The envelope consultant construction project is not to supplant the prime ar- can evaluate cost and performance trade-offs and iden- chitect; rather, he or she complements the work of the tify options that fulfill energy code requirements, main- designer by providing focused attention to calculations, tain indoor comfort, and provide long-term value. technical details, codes, standards, and material prop- Act as the problem-solver. Envelope consultants tend erties and assemblies. For new construction projects, to have extensive experience reverse-engineering build- including expansions, additions, and adaptive reuse, the ing exterior failures, which enables them to foresee building envelope consultant’s responsibilities include: potential problems and sidestep them. During con- Maximize efficient use of materials and assemblies. struction, the envelope specialist adds a level of quality Providing options for exterior envelope systems that control, verifying that key details are followed so as to meet performance objectives and budget requirements maintain energy efficiency and weather integrity, and demands in-depth understanding of material properties see that sustainability is not compromised. The building and experience with proprietary systems. The build- envelope consultant responds to unexpected technical ing envelope consultant works with the designer and questions and constructability issues to see that prob- the structural and mechanical engineers to establish lems are resolved cost-effectively and in keeping with performance requirements, then identifies products and the design intent. assemblies that are appropriate to the design and fulfill Make sure the building envelope reflects the designer’s program objectives. Often, the envelope consultant is vision – and still works. Through document review, able to suggest assemblies that reduce costs, maximize mockups, field verification, and testing, the building en- sustainability, improve efficiency, or do all of the above. velope specialist is there to focus on the technicalities of Take care of technical details. Facade enclosure re- installation and real-world performance, to see that the quirements have become so technical that meeting building envelope fulfills intended energy and sustain- complex codes and standards can absorb enough of the ability objectives. The envelope consultant can make architect’s time that it impacts building design. The build- subtle changes to construction details that address ing envelope consultant is responsible for researching technical, logistical, or practical considerations, without and applying the latest building codes and industry stan- compromising the design aesthetic. dards, and then advising the prime architect of the ways The building envelope consultant is best engaged early in which these stipulations impact design