Throughout history, the designed environment has been visibly influenced by transformations in technology, culture, and the natural world. Historians like Bashford Dean have visually chronicled the morphological evolution of human products and artifacts over the course of centuries, revealing design’s responsiveness to crises and opportunities. In the latter part of the 20th century, three megatechnologies were predicted to dominate future international industrial activity: information technology, biotechnology, and new materials.

Today, a global material revolution is now in full swing, propelled by intensified material research and development efforts as well as an acute cultural interest in creative material expression. New materials have come to shape nearly all industrial sectors, influencing building codes, environmental rating systems, and industry guidelines used in architectural offices—and while these changes provide enhanced opportunities, they also increase the complexity of architectural practice.

Given the critical role that the choice of building material plays in affecting the flows of resources, waste, and emissions, architects have realized the importance of developing more extensive material expertise in order to provide enhanced leadership regarding the design of the future built environment. But architects have, thus far, hesitated to take full advantage of the expressive opportunities of new green materials.

Invisible Green
The construction industry is still dominated by conservatism—particularly in the residential sector. In order to avert potential risks that come with novelty, green building is often disguised to look like conventional building. This approach is exemplified in the 2008 article “A Green Home Can Still Be Traditional,” published in The Seattle Times. “One of the most remarkable things about this house is it’s so unremarkable,” said the owner of a six-year-old house in Raleigh, N.C., which the reporter, Wade Rawlins, estimates to be “one of the greenest mainstream houses in the state” despite its conventional appearance.

Yet this disguised approach abandons an opportunity to differentiate sustainable design from traditional practices, and it also limits the use of many innovative green materials that might otherwise prove too visually radical. According to architect Lance Hosey, FAIA, “INVISIBLE green—considerations such as embodied energy, material sources, chemical content, and so forth—has become a more familiar agenda. … [But] VISIBLE green—form, shape, and image—can have an even greater impact on both conservation and comfort.”

Testing Possibilities
An assessment of several recent projects reveals the profound and diverse potential of material innovation in sustainable design. These works illustrate new approaches in material expression based on the redefinition of conventional building products, assemblies, and operations. One example that dramatically alters the flow of material resources within a domestic setting is Philips’s Microbial Home Probe. This project is a collection of conceptual apparatuses that transforms the home into a testing lab for carbon-neutral living. Focusing on the traditionally neglected problem of waste, the project seeks to filter and reuse all forms of household refuse—such as garbage, sewage, and wastewater. A cyclical domestic ecosystem made of a bio-digester kitchen island, an evaporative-cooler dining table, and an urban beehive, the Microbial Home Probe presents an alternative vision of domestic resource management via cradle-to-cradle-focused appliances.

Another example, the Stratus Project, redefines the function of interior surfaces and the relationships between disparate building systems. From Ann Arbor, Mich.–based design research firm RVTR, this project is a breathing, sensate, and occupant-responsive interior envelope. Composed of an array of light-transmitting polygonal cells suspended from a lightweight frame, the Stratus Project prototype is equipped with a network of integral sensors, lights, and microfans. When occupants are present, the system monitors temperature, CO2, pollution, and ambient illumination—and responds by providing targeted airflow and lighting to attain programmed comfort levels. In this way, Stratus combines conventionally separate products and trades—acoustic ceiling, lighting, and mechanical systems—to create a single, integrated envelope. Although a prototype, the system exhibits the potential to save material resources while providing greater control over interior conditioning.

The desire to produce a climate-responsive architecture prompted Stuttgart, Germany–based architects Achim Menges, Oliver David Krieg, and Steffen Reichert to design HygroSkin. This mobile “meteorosensitive” pavilion makes use of the hygroscopic qualities of wood to create a structure with apertures that automatically open and close based on the relative humidity. Inspired by dynamic natural systems that respond to changes in climate, HygroSkin is clad in thin plywood sheets perforated with collective oculi that modulate light transmission and façade permeability within a relative humidity range of 30 percent to 90 percent. The architects employed a seven-axis, robot-driven fabrication process to manufacture 28 different types of components, with a total of 1,100 humidity-responsive openings. The result is a building envelope that self-adjusts silently and without electricity, regulating light and air transmission using a single material.

New York–based studio Decker Yeadon’s Homeostatic Façade System is another example of material-based climate control, an envelope system composed of a maze-like assembly of curvilinear surfaces made of dialectic elastomers (DEs). A type of electroactive polymer (EAP), DEs exhibit large strains with the introduction of electrical current, undergoing plastic deformations with a charge and resetting themselves to their original shape once the charge is removed. With a small amount of power, the surfaces elongate or contract, adjusting the degree of solar shading as needed by interior occupants. The DE ribbons are coated with silver electrodes, which act as highly reflective light shelves when open—and magnify interior lighting when closed. Like the HygroSkin, the Homeostatic Façade System employs a material solution in lieu of a traditional, more energy-intensive electromechanical system.

Living Solutions
Designers and engineers have also created thermally adaptive envelope systems using living materials. The SolarLeaf is a bio-adaptive façade system that uses micro-algae to harvest solar energy while providing shade. Developed by Arup in collaboration with Austrian firm Splitterwerk, Texas-based Colt International, and Strategic Science Consult of Germany for the 2013 International Building Exhibition in Hamburg, Germany, this living curtainwall provides energy by capturing solar thermal heat and generating biomass. Because there is a direct correlation between solar heat gain and microbial growth, the areas of the façade receiving the greatest solar exposure also drive the highest amount of algal germination—transforming the windows into verdant shading devices. The SolarLeaf is an example of bio-design, employing living organisms as functional agents in building climate control systems—thus demonstrating a literal pursuit of “green.”

Another example reveals the capacity of materials to improve exterior environmental conditions. Superabsorber is a highway barrier replacement-system designed by Clemson S.C.–based Fieldoffice. The installation is composed of titanium dioxide–rich concrete, which photocatalyzes airborne pollutants in the presence of sunlight—causing them to fall out of the atmosphere. Clemson University’s School of Architecture associate professor Douglas Hecker and assistant professor Martha Skinner proposed the idea as an alternative to conventional sound barriers, arguing that the walls should also mitigate some of the 1.4 billion tons of highway-based air pollution emitted annually—especially since just 15 percent of surfaces clad in the material have been shown to reduce 50 percent of air pollution. At a detail level, the form of Superabsorber reflects its function: porous, spongelike cells maximize the surface area of the titanium dioxide concrete, maximizing its benefits while providing an intriguing visual texture.

Change in the Making
In combination, these examples reveal the wide variety of possible approaches to visible green. Like the models found in the natural world that typically inspire these projects, there is no singular style or method for the expression of material innovation in sustainable design. However, these works share the common characteristic of reinventing conventional building assemblies and practices with unexpected designs that lead to more environmentally responsible outcomes. Although these examples are largely in the experimental phase, their obvious benefits merit their further study and development.

According to natural resource expert David Morris, co-founder of the Institute for Local Self-Reliance, based in Minneapolis and Washington, D.C., the coming material transformation will be significant. New environmentally attuned materials, assemblies, and applications will bring about a measurable shift in manufacturing. As Morris declares: “We may be changing the very material foundation of industrial economies.”

Such a transformation represents an unprecedented opportunity for design, to invent new means of material application and expression for the most important cause of all—the health of the planet. The change will demand high levels of creativity, ingenuity, and collaboration from the entire design and construction community. However, these talents are precisely what our best educational programs and professional experiences have instilled in us. Now is the time for change—let’s get to work.

Blaine Brownell
Denise Nestor Blaine Brownell

Blaine Brownell, AIA, is an architect, author, educator, and former Fulbright scholar. He is an associate professor and director of the Master of Architecture program at the University of Minnesota College of Design.