As architects, so many of us gravitated to the profession initially from some place of altruistic origin. Make the world a better place. Help humanity and help humans live better lives. Save the environment. Do good. Above all … matter with the moments we have on planet earth.
Tied to that noble quest are the virtues of truth, honesty and authenticity. We have these virtues inside of us and they were reinforced when we learned about design in the academy. Whether translated to truth in form, honesty in expression of structure or systems, or authenticity of materiality, our instincts tend to pull us back to that altruistic origin. And so, in the context of materiality, we place a high value on the truth, honesty and authenticity of natural materials.
When thinking about options for exterior envelopes, there are almost an overwhelming number of options, and the market is ever-changing with more and more new product evolutions. The driving factors are also complex and varied. But despite all of this, it would be rare not to find cost, durability, maintenance, carbon and design flexibility at the top of the list. Our firm has experimented heavily with all of the readily available natural materials, but for this exercise, let’s focus on my three favorites: copper, zinc and Corten steel.
Oh, how we love copper! While its fluctuating cost sometimes takes it out of consideration on a project, copper is such a great option because of its natural beauty, high-recycled content, and ability to literally be crafted and sculpted and applied in any way on a project. Historically used for roofing and lasting more than a century, the material has seen a rebirth in recent decades and has been highlighted in some of the most cutting-edge architecture across the globe. Like a brand new penny in your pocket, copper slowly settles (or oxidizes) into a visually stable state. This finish depends on temperature, humidity, and overall environmental conditions, ranging from a flat, dark brown to the milky turquoise-like finish we see on the Statue of Liberty. That oxidation took more than twenty years. Copper is as natural as it gets and is visibly alive.
Zinc, by contrast, is the most visibly stable of these three natural materials. While it does have the ability to heal itself over time with a thin layer of zinc carbonate, this healing takes longer compared to copper. And while natural zinc is more visually predictable, manufacturers have become very creative in experimenting with new coatings and finishes that offer a surprisingly wide variety of appearances. From the raw or classic zinc that starts shiny and then develops a subtle blueish patina to the monochromatic ‘pre-patinaed’ finishes that range from almost black to light silver to the new color and phosphate coatings that bring chroma and depth to the palette, zinc undoubtedly has the most variability in finish options.
The warmth, texture and variable weathering of Corten steel, along with its zero maintenance and lower cost, make it an attractive option for exterior facades. Like copper, it takes on different oxidation or rusting depending on the climate, but its appearance can sometimes even vary from one façade to another. Unfinished steel, whether in plate or sheet or bent form, solid or perforated, offers significant flexibility and aesthetic range and can be used as a primary façade material or as a supporting cast accent that complements another material.
All three of these materials can be used in writing the story of a project or a client and offer significant flexibility for creativity, durability and beauty. And these natural materials also allow that story to be told in a way that feels right … with truth, honesty and authenticity.
Mark Kranz, FAIA, is vice president and design director for SmithGroup and is a member of the firm’s board of directors. Kranz is recognized as a prolific designer and thought leader nationally across the higher education and science and technology space. As one of the youngest architects ever inducted into the American Institute of Architects’ prestigious College of Fellows in 2017, his projects have won more than 175 design awards including 21 Metal Architecture Design awards over the past two decades.
National Renewable Energy Lab Energy Systems Integration Facility, Golden, Colo.