Mastering the higher ed campus building envelope
Mastering the building envelope on college and university campuses requires addressing both cultural concerns and technical performance, honoring traditional buildings while exploring the potential of new materials and forms.
Building envelope choices for campus, cultural, and infrastructure projects are shaped by particular conditions. Today, institutions place greater value on how buildings relate to their ensemble: how historic buildings fit next to new ones, how massing forms fit with their neighbors, and how a building cladding contributes to the campus context. Concurrently, enclosure assemblies and construction methods have undergone changes due to values of sustainability, science, durability, and maintenance.
In this context, mastering the building envelope on college and university campuses requires addressing both cultural concerns and technical performance, honoring traditional buildings while exploring the potential of new materials and forms.
A Carbon-Free Future
Across the U.S., colleges and universities are raising the bar for sustainable building with aggressive targets for campus carbon neutrality. Since the American College and University Presidents’ Climate Commitment (ACUPCC) first initiated a nationwide framework for action in 2006, universities have made specific commitments to reductions in greenhouse gas emissions. They have established quantifiable goals and metrics to measure success and publicly posted progress reports.
These climate action plans are driving campus investment in renewable energy sources, reduced emissions in food and transportation systems, and energy-efficient buildings. Colleges and universities are one of the most active client groups requiring buildings to achieve goals for energy efficiency and use of sustainable materials. Some institutions require high LEED accreditation and aspire to net zero or Living Building Challenge benchmarks.
These goals parallel the architecture profession’s commitment to addressing climate change. First issued in 2006, the AIA’s 2030 Commitment tasks the architecture and building communities with prioritizing energy performance and carbon reduction in the design of carbon neutral buildings, developments, and major renovations by the year 2030.
At the same time aspirations to carbon neutrality drive the on-campus discourse, incremental code updates are elevating the minimum energy performance of new buildings. The widespread adoption of the International Code Council code suite has created a single standard for prescriptive building envelope design. The continuous insulation requirement—first introduced in the 2003 IECC for stud walls in climates zones 6a and higher—has increased and pushed further south, reaching all the way to zone 1 by 2012.
In partnering with colleges and universities, architects have the opportunity and the obligation to transcend code-mandated minimum requirements and to advocate for innovative, high-performing building enclosures that set institutions on the path to achieve their energy and sustainability goals.
Energy efficiency is not the only driver of envelope design on campus—colleges and universities are also long-term guardians of all aspects of their campus environment. A coherent material palette, realistic maintenance requirements, and student wellbeing are also key considerations in enclosure design.
Durability and maintenance are continuing values within campus facilities departments. With the increasing competition of attracting students and opening new facilities, minimizing maintenance on the existing physical plant allows for more resources to be moved into campus improvement. Building durable façades is key to reducing this maintenance.
Stewards of Campus Identity
Building cladding is an emotional issue for campus design. The image of the American campus evokes Collegiate Gothic, neoclassical, or ivy-covered brick buildings, and this image often powers aesthetic decisions considering context, massing, and cladding.
A common contextual choice for campus building cladding is masonry, and today that means masonry veneer walls. On the surface, brick and stone are durable, colorfast, and require little maintenance. A veneer wall requires an air space and a back-up wall, and that is the weakest component. The common cold climate wall system includes cold-formed metal studs with a gypsum cladding, rigid insulation, an air space, and the masonry veneer. The veneer is held by clips screwed in through to the metal studs.
The vertical loads of the wall are carried by the foundation, and the relieving angles are carried to the structure. The entire horizontal support of the wall, however, relies on the physical connection between the screw and the metal studs. This can fail with the attachment process, the screw thread can spin in the thinner gauge metal stud, or rust can form at this joint. These issues can compromise the integrity of the connection.
History and aesthetics aside, precast concrete panel systems are a cost-effective alternative to a stone veneer. A precast panel can span several floors, be erected quickly, and accommodate custom joints, different colors, and textures. They are attached directly to the structure and, unlike other cladding systems, the interior studs, insulation, and finishes can be erected after the panels are in place. However, concrete is more absorptive than brick and hard stone, and can show discoloration over time.
Another “masonry” cladding material that is increasing in popularity is terra cotta. This approach comprises an extruded shape available in various heights and colors hung from a rainscreen system. It is larger in scale than brick but conveys a similar texture and finish of brick with precise reveals and no mortar joints.
Unlike brick, which has a variegated texture when laid up, terra cotta is uniform and flat, with crisp joints. Like brick, it is very durable, stable, and looks as good over time. On one hand, it can suggest a more corporate image, but at the same time, due to the similarity of the material to brick, it can be seen as a more formal and modern approach to a time-honored material.
Improving the Old Wall
Old, stately masonry buildings are common on campus and revered for their history and sentimental value. Bringing them up to modern codes raises many issues affecting the integrity of the envelope. For historic buildings, multi-wythe walls allowed moisture in and out as they dried out from both sides. This equilibrium worked for the life of the building.
However, this flow of moisture through old masonry walls is usually accompanied by a flow of heat and excessive space conditioning energy loss. As we seek to make these walls more efficient through the addition of modern insulation, key questions arise about the aesthetics and durability of the improved, hybridized wall. For the wall alone, the ideal solution is to put the insulation layer on the outside, which keeps the masonry warm and at a relatively constant temperature. This is not an acceptable solution for beloved, historic campus buildings, so what steps can be taken to optimize the R-value without compromising the exterior?
The critical challenge in adding insulation to the interior face of existing walls is to create a thermal barrier without introducing an impenetrable vapor barrier. This allows old walls to continue drying on both sides—inside and out—as they have always done. Careful consideration of the dew point within the wall is necessary to avoid creating new problems while solving old ones. If condensation occurs within the masonry itself and drying potential is limited, the freeze-thaw cycle can degrade the integrity of the wall. Spalling or deterioration of the brick and mortar can result.
Our firm recently tackled this issue at Middlesex Community College’s (MCC) Donahue Family Academic Arts Center, a new student performing arts center inserted within a historic-but-crumbling train depot in the heart of downtown Lowell, Mass.
The existing conditions of the original exterior wall were highly varied—visual inspection identified a load-bearing brick wall from two to eight withes deep, as well as mixed stone. Unknowns abounded, and destructive testing was not a viable approach given budget limitations. Working within these constraints, the team took a conservative approach to improving the energy performance of the enclosure, based on prescriptive methodologies.
After weighing various options for vapor-permeable insulation—mineral wool, open cell spray foam, and closed cell spray foam—the team selected a closed cell spray foam application. Closed cell foam has the advantage of providing integral air and water barriers, proven durability, and high R-values at thinner applications. In this case, one-inch of closed cell foam resulted in an R-10 exterior wall.
The MCC renovation completely removed the existing interior partitions and roof in order to insert a proscenium theater, music recital hall, and a dance studio inside the exterior skin of the original train station. This allowed the opportunity to improve other parts of the building envelope, replacing all windows with double-glazed, low-e, clad wood units, and creating a high-performance (R48) roof.
The site of the new performing arts center, within the Lowell National Historic Park, is part of the city’s renewed urban core. The project serves as a catalyst for future urban development and cements the college’s commitment to an urban campus.
Beyond the Brick Wall
Innovative new programs—driven by emerging tech and inter-disciplinary cross-pollination—are a powerful vehicle of change on college campuses. Housing these programs often requires designing innovative spaces and developing a fresh material palette. Metal and glass can add interest to an ensemble of buildings, working in dialogue with the materiality, scale, and organization of the campus.
Metal cladding is a cost-effective material and is chosen for residence halls more than academic buildings. It can take the form of metal panels or sheet metal cladding. Metal cladding can raise issues with durability, color fading, and maintenance due to sealant longevity. Metal panels and interlocking extruded shapes are a more formal material than formed sheet metal, which is shaped sheet employed to introduce rigidity in one direction.
At the Wentworth Institute of Technology in Boston, a new academic program focused on engineering innovation suggested a material departure from the typical muted yellow-gray brick campus. The Center for Engineering, Innovation, and Sciences provides a home for the next evolution in the collegiate study of multiple engineering disciplines. This four-story, 75,000-sf building comprises a dynamic environment for multi-disciplinary collaboration among students of biology, civil engineering, mechanical engineering, biomedical engineering, and biological engineering.
The building’s massing and alignment are carefully contextual, strengthening the form of the center campus quad and extending a key pedestrian route across campus. However, the material expression is boldly distinct, with a perforated zinc veil wrapping building from north to south. The exposed street and quad faces are expressed as glass and zinc panel volumes (see sidebar, opposite page).
High Performance Glazing
On Earth Day this year, New York City Mayor Bill DiBlasio stood in front of new glass clad towers and said that with a new building code, the City will no longer allow structures such as these. He implied that a curtain wall has very high heat loss in the winter and heat gain in the summer, leading to ballooning energy costs throughout the year. With the low R-value and the obvious greenhouse effect of glass, this is basically true.
Although highly insulated walls are inexpensive and can quickly pay for themselves in energy savings, highly insulated clear glass is much more of a cost challenge. Translucent glass can perform well. Solutions range from filling the cavity with translucent insulation to adding phase change materials to a thick glass framework. These allow for filtered natural light to enter the space, but they have the distinct downside of creating glare and prohibiting the ability to look outside. Currently, with little advancement in technology over the years, a cost-effective high R-value curtain wall remains elusive. Added glass layers and filling the void with inert gases help incrementally, but these are all outpaced by the significant jump in cost.
A double skin façade—two curtain walls separated by an accessible space in between—is a possible solution, but they have a record of not performing as well as energy models suggest. First, DSF requires an installation of several floors to allow for the air circulation and the chimney effect in the cavity in order to relieve summer heat gain. A two-story double skin façade, for instance, is shown to be ineffective and more than doubles an already expensive cladding cost. Second, the cavity of a couple of feet or more either takes away from useable interior space or exterior build-out.
Our firm’s recent project at Dartmouth College explored alternatives to double-skin facades that deliver a high-performance glazed skin. Dana Hall originally served as the college’s medical school library, but a complete renovation—preserving only the original structure—creates a new graduate student center, departmental swing space, and campus café. A new addition to the south anchors the building within its context, defining an inviting northern quad and creating shared social work space inside. For this glazed southern wing, visibility, glare, thermal comfort and energy conservation were all addressed by translating the double skin concept into a fused skin resolution.
Double Skin Concept / Fused Skin Resolution
The glazing strategy for Dartmouth College’s Dana Hall combines careful proportions, locations, recesses, canopies, and topography with advanced technologies. The triple-glazed punched windows on three sides of the building are tall and set deep in the wall with two low-E coatings to minimize heat gain. Continuous curtainwall glazing at the ground floor is under cover from the floor above, and at the penthouse, shaded by the photovoltaic canopy.
The new south addition is clad in an advanced all glass façade system designed with passive measures and active controls to produce a thermally efficient envelope responsive to its environment. The glass façade is made of 2-inch quadruple-glazed insulated glass units and high-performance vacuum insulated glass panels arranged in response to orientation and maintaining visual connection and transparency between inside and out. Both units have integral expanded metal mesh shading and are silicone structurally glazed to a thermally-broken aluminum curtainwall. Each component is optimized for thermal performance with a whole system R-value >8, four times more efficient than the latest energy code requirement. The system also pairs automated vent windows in the vacuum insulated glass panels with interior daylight responsive shades at vision panels to allow simultaneous daylight control and natural ventilation.
Working on the American campus today provides a unique set of design opportunities. Colleges and universities tend to be forward-thinking institutions that seek to inspire their constituencies—students--and are concerned with their buildings in the ensemble. As stewards of their built environment, higher education clients are motivated by a complex set of values: providing long-term building performance and durability; ensuring a coherent campus identity; preserving, adapting, and improving existing building stock for emerging student use, and expressing the innovative nature of new programs. The richest, most interesting campuses include buildings from various eras, conveying the spirit of the time in which they were designed and built. New technology and building science have the capability to maximize facade durability so that structures from all architectural periods remain as long lasting as possible.
Design Assist: Bridging Envelope Design and Construction
Design assist is a procurement process that brings subcontractors on board early—during the design process—to assist the design team with the development of detailed construction documents. Design assist aims to streamline the design and fabrication processes, eliminating duplicate efforts between construction detailing and shop drawings.
On Wentworth Institute of Technology’s Center for Engineering, Innovation, and Sciences project, Gilbane (CM at risk) took the initiative in proposing a design assist relationship. Sunrise Erectors joined the team in a design assist capacity at mid-DD (design development). The firm’s bid was based on schematic design drawings, a narrative, and established target value for the envelope.
Understanding Design Assist Roles on the Wentworth project
- Where the design team took the lead: Our firm developed the detailing of the façade systems, with Sunrise Erectors reviewing and commenting.
- Where the subcontractor took the lead: Sunrise introduced a new curtain wall manufacturer—ES Windows—that was able to provide a stick-built curtain wall system at a considerable savings over the typical basis of design competitors. In order to convince the architecture team of the level of quality of the new manufacturer, Sunrise Erectors brought the project architect to the ES Windows factory site in Colombia to show the fabrication process first-hand. This peek into manufacturing capacity helped resolve concerns about different levels of anodization quality and subtle distinctions in the finished product.
- Key synergies: With a manufacturer on board, our firm could detail with greater confidence. Panel maximum sizes, connection details, and tolerances could all be based on the specifics of the final production system. Shop drawing changes were kept to a minimum because design decisions and details were based on real fabrication capacity, saving both time and money.
Working with Metal Cladding
The Center for Engineering, Innovation, and Sciences at the Wentworth Institute of Technology in Boston incorporates three different metal wall cladding systems. The two used as highly visible finishes were both zinc, a natural metal that weathers to slowly develop a protective zinc carbonate patina with a soft grey color. Where the metal panel was partially concealed behind a perforated screen, a Kynar high-performance fluoropolymer resin finish was used instead, to provide a durable color and finish at a lower cost.
1. Solid Zinc panel rainscreen system
- Cladding: 16ga formed plate solid vertical cassette panels
- Attachment: face fastened at joint reveals to concealed aluminum horizontal girts
- Back-up: horizontal girts mounted from thermally-broken Z-clips, 4-inch Rockwool continuous insulation, peel-and-stick AVB membrane, gypsum sheathing, cold-form metal studs
Key Considerations: Keep an eye on the corners where vertical and horizontal joints meet. Asymmetrical corner tabs or interlocking corner details may be required to conceal the back-up systems beyond. Review sample details to confirm that they match the full-scale assembly.
2. Perforated zinc screen (veil)
- Cladding: perforated vertical cassette panels, pre-patinated mill finish zinc, ¼-inch round holes, 30% open area
- Attachment: face fastened at joint reveals to exposed 1½x1½-inch stainless steel girts.
Key Considerations: Fastener penetrations can create a vulnerable opening in exposed galvanized steel, piercing through the protected galvanized surface. Field-applied zinc-rich coatings can provide additional protection, but vary widely based on the care and craft of application. At Wentworth, stainless-steel framing was used instead of galvanized steel behind the perforated veil in order to eliminate the danger of rusting at fastener penetrations.
3. Insulated metal sandwich panel (behind THE veil)
- Cladding: integrated sandwich panel with 4-inch polyisocyanurate core and galvalume face panels with a Kynar finish; interior metal face is effective AVB
- Attachment: fasteners concealed in interlocking double tongue-and-groove preformed joints
- Back-up: gypsum sheathing, cold-form metal studs
Key Considerations: This industrial sandwich panel was used behind a perforated finish screen in order to reduce cost (by providing integrated insulation and AVB) and assembly time on site.