Efficiency-Driven Facade Optimization

Introduction to the New Australian Embassy: Enclos is proud to have provided the facade for the recently completed new Embassy of Australia at 1601 Massachusetts Avenue in Washington, D.C. Designed by the Australian architecture firm Bates Smart, it replaced the previous modernist embassy also designed by Bates Smart, which opened its doors in 1969. For the new chancery, which opened in August of 2023, the major feature of the façade is its copper panels which are meant to evoke the colors present in the Australian landscape found in places such as the large sandstone formation named Uluru (also known by the name Ayers Rock).

image 1: Embassy of Australia | source: RBAP? (final pro photos on the projects drive….) image 2: Uluru | source: https://pixabay.com/photos/ulu...

Phase 1 – Chasing Dollars: The initial architectural design for the main exterior façade presented a challenging curtain wall unit typology. Bates Smart’s original concept had the glass units projecting from the structure and meeting the copper panels at an apex away from the edge of slab by as much as 25 inches. (figure #1) In addition, the joints between copper and glass were not planar due to the nature of the proposed façade geometry and this resulted in glass units which would have been warped out of plane beyond the limits of cold bending. (figure #2) These two features of the curtain wall unit typology, in combination with the premium for the copper alloy panels, caused the initial pricing estimates for the façade to come in well above the proposed budget. In the summer of 2018, five years before the building would be completed and turned over the Australian Government, Enclos was engaged directly by the Department of Foreign Affairs and Trade (DFAT) and asked to help Bates Smart craft a façade that still met the design intent while being within the budget allocated for the project.

Given a dictum that the copper panels were integral to the spirit of the project, the initial strategies Enclos employed for cost reduction were aimed at making a minimal impact on the design intent given by Bates Smart. Firstly, Enclos suggested reducing the number of the unique unit types by combining units with similar materiality layouts (within 6” difference in spandrel width) (figure #3) and reducing the projection of the apexes of the most extreme trapezoidal units from 25 inches from the face of slab to 22 inches. In addition, studies were conducted aimed at rationalizing the sloping apexes of the curtain wall frames to produce topography to the façade which would require only flat or minimally cold bent glass units. Once completed, costing models were rerun, and the attendant figures were provided to DFAT. Unfortunately, the façade was still over the budget set by the Australian Government.

By January of 2019, it was clear that something more radical would be required in the value engineering of the façade. The initial optimization had resulted in a disappointing flattening of the topography while failing to reduce the costs to get within the budget. Working closely with design architect Bates Smart, Enclos developed an exponentially simpler alternate curtain wall system typology which kept the glass units and the curtain wall framing flat and rectilinear while putting all the topographical expression of the façade into the copper panels integrated into the unitized system. This did two things simultaneously. First, it brought the cost and complexity of the façade engineering down dramatically while reducing the square footage of glass and eliminating the warping of the IGUs required by the initial design. Secondly, that reduction in cost and complexity was significant enough that it allowed Bates Smart to regain depth in the topographical expressions and produce more unique widths and depths of the folded copper panels, essentially undoing some of the previous rationalization of the optimized base design. Enclos provided multiple full building renderings of design iterations and potential panel layouts to Bates Smart and DFAT, ensuring there were no surprises in the completed façade. After a period of 6 months of close collaboration between Enclos, Bates Smart, and Washington D.C. based architect-of-record KCCT, the outcome was a reduction of 23% from the base bid cost of the façade and an alternate design that held close to the spirit of the original façade concept. (see images 3, 4 & 5)

figure #1: original façade concept | source: Enclos

figure #2: original warped glass topography | source: Enclos

figure #3: example of original unit typologies | source: Enclos

image 3: Base bid design | source: Enclos

image 4: optimized base bid design | source: Enclos image 5: alternate design | source: Enclos

Phase 2 – Chasing Copper:

The copper panels on the Australian Embassy were originally envisioned with a highly organic and non-uniform finish made by applying a flame and burnishing the material to discolor it, producing an effect some described as having rainbow like reflections – like gasoline when it floats on water. This finish would then have to be protected from typical copper patination by overcoating it with a clear lacquer or poly-type finish. Bates Smart had been engaged in a research and design effort with a panel manufacturer and had produced small samples of a copper material with a finish they wished to attempt to spread across the entire scope of the project. See image 6.

image 6: flame burnished copper sample | source: Enclos

During further discussions with the panel manufacturer who provided the sample, the design team discovered there were concerns about producing the volume of material needed for the building in the timeline the project required. The full project would need nearly 760 panels in approximately 350 different unique shapes, ranging from 26 to 80 inches wide and 105 to 282 inches tall. In addition to the scope, there were concerns about controlling the color range of the non-uniform finish. After many trial rounds on full size material and several visits to multiple panel manufacturers during the project’s design-assist phase, the decision was made to forgo the flame-burnished finish in favor of panels made from coils of mill finished copper. In part, unfortunately, this decision also stemmed from the start of the COVID-19 pandemic in March of 2020 and the suddenly near impossibility of continuing the R&D process with shop visits to panel manufacturers around the globe.

Ultimately, these mill finish panels would be clear coated with a protective polyurethane lacquer product called Durodur 3057-20089 Clear S-Mat (satin matte) and coated a second time on top of that with a clear wax; Collinite No. 885 Heavy Duty Fleet Wax (marine paste wax). The ultimate goal of this two-coat finish was to preserve the copper’s mill color for as long as possible and to avoid the discoloration of copper known as patination. Copper’s patina color will vary depending on the availability of carbon dioxide and water in the air, and the city the material is in can influence this availability. Larger cities have more aerosol sulfates which are produced by burning fossil fuels and this tends to turn the copper oxide a dark shade of green. In the metro area of Washington, D.C., the concern was that the copper panels, if left unprotected, would eventually patinate to a dark shade of brown.

In addition to preserving the color, the copper panels required careful isolation from the aluminum framing of the curtain wall to prevent galvanic corrosion of the aluminum unit framing itself. To this end, a chassis of stainless-steel shapes was used to mount the panels and separate them from the curtainwall framing. These stainless-steel sub-assemblies were mounted on the curtainwall frames by one of

Enclos’s vendors near Bangkok, Thailand. The completed units were then sent to a staging yard near the job site before making the final trip to the project site for a just-in-time delivery prior to setting.

Once the units were on site, the copper panels were installed onto the integrated stainless-steel frames before the units were lifted into place on the building structure. This “drop shipping” of the copper panels to the job site allowed for minimal handling of the noble metal and meant that the topography of the units was reduced for more efficiency in packaging and shipping.

Phase 3 – Chasing the Startline

The design assist phase, of course, had to answer many more questions than just the finish of the copper material, as critical as that was. With a goal of transitioning into production engineering by August of 2019, it was imperative to keep focused on multiple fronts. These included definitions of scope, design criteria, structural coordination, thermal and acoustic coordination as well as defining the final building geometry. In addition, there were also other infill materials to select, not the least of which was the glass – including its coatings and the supplier. Paint finishes also needed to be selected for the framing and the shadowbox panels. All these varying inputs and constraints applied not only to the primary exterior façade, but also affected the several other façade system types on the building including a dramatic light well and attendant interior courtyard.

With so many variables to keep track of during a design assist phase, Enclos has come to rely on a unique tool we create in collaboration with other members of the design team. Referred to as a priority workflow, it is essentially a graphical representation of required design decisions laid out as sequentially as possible against a backdrop of the design assist phase timeline. Key players for each decision are identified by color and those colors are assigned to items in the workflow so that all parties know what they are responsible for coordinating. Milestone dates separate major inflection points in the process and it all ultimately leads towards a set of defined deliverables. For the Embassy of Australia, those deliverables included:

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The final value of the curtainwall scope

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Approved system profile drawings

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A full thermal analysis and report

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A full structural analysis and report

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A documented site logistics plan and attendant means & methods

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A project schedule

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The scope for the Performance Mockup defined and documented

The included priority workflow for the New Australian Embassy (figure #4) is a reflection of all that goes into a monumental building before the project engineering has begun and long before material reaches Enclos’s shops or the final unit assemblies arrive on site. As we look back on the now completed Embassy, it’s with great pride that we reflect on the hard work of the entire project team during this early design collaboration phase and look at the original renderings and compare them to photos of the now completed chancery.

figure #4: Australian Embassy Priority Workflow | source: Enclos

image 7: Original rendering from September of 2019 | source: Bates Smart

image 8: completed photo from October of 2023 | source: RBAP

Introduction to the San Diego Terminal #1 Headhouse Façade:

The curvilinear and luminous façade for the headhouse at the San Diego Airport Terminal 1 replacement is the culmination of a multitude of iterations and design studies led by James Carpenter Design Associates (JCDA), Gensler, Walter P. Moore, Starq & Enclos. We are proud of our role in providing early budget feedback and engaging in a collaborative design-assist-project with the design team, ultimately delivering a world class façade for the people of San Diego and those who travel there.

When Enclos was approached by Turner Construction in January of 2021, the design team for the project was in the process of evaluating multiple iterations of the bespoke façade for the headhouse. A major concern was daylighting and the potential glare for the staff working inside the ticketing area. Several strategies for creating shading and diffuse light were being explored. These included staggering the plane of glass from the front of the system to the back in alternate modules (figure #5), a floating curved and fritted glass brise-soleil 10’ in front of a flat glass façade (figure #6), and a staggered flat glass and curved glass approach with a floating terracotta brise-soleil in front of the flat elements (figure #7).

figure #5: alternating glass planes from front to back | source: James Carpenter Design Associates, Inc. ©

figure #6: curved glass brise-soleil | source: James Carpenter Design Associates, Inc. ©

figure #7: staggered curved glass / terracotta brise-soleil | source: James Carpenter Design Associates, Inc. ©

By the start of June of 2021, the design had started to progress to a single façade skin and the floating screen elements had been eliminated to reduce overall material costs and to simplify shipping and field labor concerns. While slightly more traditional than the dual skin approaches, the three options being pursed were certainly not simple; Option A was a convex J-curved IGU on steel verticals (figure #8), option B was a concave J-curved IGU on steel verticals (figure #9), and option C was a flat glass façade with opaque glass fins of varying depths and heights spaced across the unit module (figure #10) .In addition to the façade geometry itself, the load path for the façade was non-traditional as well. The prevailing thought was that the façade verticals would be hung from the canopy roof and braced back at the 2nd floor slab.

figure #8: convex J-Curved façade | source: James Carpenter Design Associates, Inc. ©

figure #9: Concave J-Curved façade | source: James Carpenter Design Associates, Inc. ©

During all these studies, Enclos solicited vendor feedback as well as getting input from select manufacturing partners and our own field and shop crews to provide the design team costing models and budget pricing for the various iterations. By late June, the design had begun to coalesce around an option for a convex IGU glazed to a small aluminum cassette. The shop glazed cassettes were to be field hung onto the steel fin which was the deadload support suspended from the roof as well as the shading device. At this point the façade design had a name as well – “The Luminous Wave Wall” and its expression was meant to evoke the interplay of light and water in the San Diego Pacific surf zone. (figures #10 & #11)

Figure #10: singled curve IGU with fin | source: James Carpenter Design Associates, Inc. ©

Figure #11: Luminous Wave Wall | source: James Carpenter Design Associates, Inc. ©

Exploring and refining the Wave Wall

With the basic façade expression now relatively well defined, design studies began to turn towards optimizing the façade system for ease of fabrication and installation, as well as furthering opportunities for material reduction. Enclos provided many details and renderings of iterations to the design team for their review and feedback. One early option looked at was to put the steel verticals inside the weather line and to make the vertical fin aluminum (figure #12). Another exploration was to forgo the steel fin hung from the roof in favor of cantilevering the glass unit past the vertical to provide the shading. To do this would require supporting the cassette units from horizontal AESS steel trusses hung from the roof by rods. (figure #13 & 14)

figure 12: early concept detail at vertical | source: Enclos

figure 13: early concept detail at vertical | source: Enclos

figure #14: early concept rendering | source: Enclos

After pursuing the strategy of cantilevering the glass and its attendant fritting, it was determined that for shading and logistical reasons, a metal fin was preferable. Due to the high cost of field labor for stick or hybrid approach, the steel trusses for bracing the wall at the midspan of the double height space remained. This allowed for the complete unitization of the glass and a more traditional weather line for the façade, as opposed to steel verticals passing through the plane of the wall and bringing potential moisture and thermal problems (figure #15). The trusses would be hung from the roof and the curtainwall units would therefore be deadloaded to the roof. At level 2, the wall would be decoupled from the slab by a series of connections allowed to move vertically. Originally this was conceived as being done with tension springs, but in the final detail was achieved with a hinged pin connection (figure #16).

figure 15: refining the typical vertical detail | source: Enclos

figure 16: decoupling the façade from the slab with a rotating pin connection | source: Enclos

Refining the expression

The typical glass lites for the headhouse wave wall are made with a half-inch thick laminated outer lite and a quarter-inch thick inner lite. They are concave curved with a constant radius of 5’-6” and a module spacing of 5’-4”. They were produced overseas by Beijing Northglass. Due to the heavy makeup and the complexities of getting curved samples in a timely manner, Enclos worked closely with the design team to refine the frit options using our visualization group to produce high quality renderings for review. In addition to frit options, the design team also used renderings to narrow in on sealant colors before ultimately producing a visual mockup.

One of the early frit patterns the design team explored was a stochastic pattern of dots. A stochastic pattern is randomly determined with a probability distribution or pattern that may be analyzed statistically but may not be predicted precisely. This pattern designed by JCDA and Walter P. Moore gradated from transparent to opaque across the unit in width so that the shading grew increasingly dense as it approached the metal fin. Figures 17 & 18 show a four way intersection with the stochastic pattern and two different sealant and gasket colors. In addition to refining the glass expression, the shading fin was given a textured treatment of vertical ridges in the die profile to carry the texture of the glazing infill into the shading device. (figure 19)

figure 18: stochastic frit pattern with black sealants & gaskets | source: Enclos

figure 19: stochastic frit pattern with gray sealants & gaskets | source: Enclos

figure 20: vertical texture added to the sunshade fin | source: Enclos / James Carpenter Design Associates, Inc. ©

By the summer of 2022, the design team decided to forgo the stochastic frit pattern in favor of a gradated vertical pattern of lines that would change across the vertical height of the elevation. The gradated shading and fin explicitly address late afternoon sunlight at a low angle. The fin shades the portion of the glass providing unobstructed views to downtown San Diego. Again, prior to receiving samples and prior to building the physical VMU, the visualization group at Enclos provided the architectural design team with high quality renderings as proof of concept. These were then developed through full size mockups with JCDA. Figures 21 & 22 show the updated frit pattern renderings. Images 9 & 10 show the completed visual mockup. Note the two spandrel conditions also being evaluated.

figure 21: updated vertical frit pattern from exterior | source: Enclos

figure 22: updated vertical frit pattern from interior | source: Enclos

image 9: exterior view of the VMU | source: Enclos

image 10: interior view of the VMU | source: Enclos

Ultimately the success of the San Diego Terminal 1 Headhouse is due to the collaborative efforts of the entire project team. The innumerable decisions, both large and small, made during the design assist phase as a collective group shape not just the expression of the façade and the quality of the componentry, but also impact the project schedule, the budget and ultimately the lives of the individuals tasked with building it and those who will experience being in it as workers or travelers. Enclos is proud to have assisted James Carpenter Design Associates, Gensler, Walter P. Moore, Starq and the entire ARRIVE San Diego team in the completion of this modern masterpiece of infrastructure.

image 11: the Luminous Wave Wall under construction | source: Enclos

image 12: the Luminous Wave Wall under construction | source: Enclos