Volume 26, Issue 2 - March/April 2012


First in Fashion
New Glazing Trend Sets the Stage for Future Façade Applications
by Ellen Rogers

Sometimes it’s the simplest of ideas, designs, fashions and trends that make the biggest statements. Think Audrey Hepburn circa “Breakfast at Tiffany’s.” To this day few items make as much of a fashion statement as a simple black dress and a few strands of pearls. And a simple, yet memorable statement, was exactly what the Spanish architectural firm of Rafael de La-Hoz was going for when it designed the new facade for the home of Inditex, the company behind fashion brands such as Zara, Pull & Bear and Massimo Dutti, located at Castellana 79 in Madrid, Spain.

“We were looking for an abstract and plain composition for the façade that wouldn’t penalize the view from the inside because of the façade ‘character,’” says design architect Francisco Arévalo. “The client’s request was to have a singular building, but discreet at the same time, with an impeccable function as an office.”

Glass and glazing materials played a key role in bringing this architectural creation to life. Arévalo says they looked to the squares of a chessboard as the design inspiration, while also incorporating a double skin to provide natural daylight penetration.

“This resulted in a neutral, abstract and plain façade, but at the same time [one that is] alive, with volume.”

Setting the Stage
When it came to the early stages of the design process, Arévalo says the location of the building within the city posed a challenge.

“Located next to one of the best office towers in the country of one of the great masters of 20th century Spanish architecture—Francisco Saenz de Oíza—[the location] raised the idea of respecting the past, yet being able to differentiate our styles from the rest of the buildings without much architectural show-off,” says Arévalo. “We could not compete with the Banco de Bilbao Tower in height (it stands 107 meters) nor the location, but we [also did not want to] merge with it.”

He continues, “These urban premises and the client’s requests to have a singular, but at the same time, discreet building, conditioned the concept of the project from the very first moment.”

So when designing this new office building, Arévalo says a number of components came into play. These included not only the aesthetic, but also the performance features.

“Because it was the first time being used in an exterior project, the testing was the biggest hurdle to overcome. Once that was completed the fabricators could move forward comfortably. Testing was paramount to the whole process.”
—Peter Katcha, Sefar

“From our experience, especially with office buildings in Madrid, having a double skin façade helps the interior comfort, both acoustically and thermally, so we considered this façade solution from the very first moment,” he says. “The building location, in one of the great thoroughfares of the city and the south orientation, also advised this solution.”

But there was also the aesthetic appeal—the checkerboard appearance—and the question arose as to just how to make such a look work, while still ensuring the views of the outside from within.

“We searched all sorts of glass treatments: silkscreen with different degrees of opacity and color, [acid] treatments, sandblasting, [working] with different colored sheets of butyrals, but all of them affected the view from the inside,” says Arévalo.

Then there was the idea of incorporating a metal mesh. Arévalo explains that on many other projects his firm has worked with companies that specialize in laminated glass with metal meshes, but the concept never worked well. For example, a true metal mesh can come with a high price tag, for one, and also add weight to the glass, making it difficult to work with and install. Other reasons he says such previous materials were unsuccessful include the fact that they had either not passed testing requirements for use on façades or did not meet their architectural aesthetic expectations.

Already working with DuPont’s SentryGlas laminated glass products, the architectural team soon learned of a product called Sefar Vision, which is an alternative to traditional metal mesh; it’s a metal-coated fabric interlayer, typically laminated within glass or other transparent materials.

Peter Katcha, director of North American sales with Sefar, says that while double-skin facades are popular in Europe, creating one with just a laminated glass product does not provide much of an aesthetic, and the aesthetic feature was something architects were looking to capture.

“[DuPont] introduced [to architects] Sefar Vision in combination with SentryGlas, which provides a nice aesthetic, an almost 3D appearance to the façade,” says Katcha.

While Arévalo says he was interested in working with the Vision product, there was a challenge: at the time it was not approved for use with glass in an exterior façade in Spain.

“We had samples of laminated glass with metallic interlayers and Sefar meshes in the office, but none of them could be used at that time outdoors,” he says. “We got in touch with official Sefar suppliers in Spain and after several negotiations we reached the [opportunity] to use it, since it was already in testing and standardization processes in our country and [and would be ready in time to meet] construction dates.”

Katcha says his company worked closely with DuPont on a battery of tests to ensure the product would work in exterior applications, as previously it had only been used in interior applications. This testing procedure included those for adhesion, edge stability, high temperature resistance, high moisture resistance and lightfastness.

“It was that testing that made it possible to use Sefar Vision in this project,” says Katcha. “Because it was the first time being used in an exterior project, the testing was the biggest hurdle to overcome. Once that was completed the fabricators could move forward comfortably. Testing was paramount to the whole process.”

Finishing Touches
The resulting project features a glass curtainwall created to resemble a three-dimensional checkerboard with alternating panels of clear laminated glass and panels embedded with the mesh product. Each panel is approximately 11.2- by-6.4 feet and consists of two layers of 8-mm, low-iron tempered glass laminated with .52-mm SentryGlas. The reflective aluminum coating allows the façade to come alive with depth and light refraction that mirrors the changing outdoor conditions of the sun and clouds. From the inside, building occupants have an unobstructed view of the outside. The glazing systems reduce glare from the sun and reflect the warmth away from the building, helping reduce the need for air conditioning.

A number of companies were involved in the fabrication, all of which took place in Spain. The glass was cut and polished by Vitro and Cricursa did the lamination. The Spanish firm Caamaño and Metalvedro served as the installers and assemblers of the façade.

“From our experience, especially with office buildings in Madrid, having a double-skin façade helps the interior comfort, both acoustically and thermally, so we considered this façade solution from the very first moment.”
—Francisco Arévalo,
Rafael de La-Hoz

Since the project was the first to use the Vision product in an exterior application, and considering the necessary approval and testing, Arévalo stresses that a “very direct and intense collaboration with both the supplier and installer” was critical.

Katcha agrees that communication was important.

“Working together was important to make sure everyone would be confident in ensuring the design concept could be realized,” Katcha adds.

True to Form
Aside from being the first project to incorporate the mesh product in an exterior application, Arévalo says there are some other details about this project that make it unique.

“The ‘rehabilitation’ part, where we had to respect the existing steel columns of the previous building, demolish all the floors and walls and reinforce the foundations of ancient buildings was a challenge, but a successful one,” he says. Speaking of the architectural details and features found within the city of Madrid itself, he adds, “Being able to offer both our client and the city a simple design [that’s also] full of expression and nuance in one of Madrid´s most populated districts [was a great learning experience].” AG

Ellen Rogers is the editor of the Architects’ Guide to Glass & Metal magazine. She can be reached at or follow her on Twitter @AGGmagazine and like AGG magazine on Facebook to receive updates.



Architects' Guide to Glass & Metal
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