Skins and Bones

ARCHITECTURE magazine, August, 2005

Lance Hosey 

Sustainability may never realize its full potential in architecture until it revolutionizes structural design. 

The relationship between envelope and structure has influenced every significant architectural development in every culture since the dawn of construction. Today, while sustainable design has become a strong force in global architecture, so far it has concentrated on one of these systems and neglected the other. In the last decade, considerable progress has been made with façade technology— phototropic sunshades, energy-producing cladding, light-activated glass, thermally activated metals, and even pollution-absorbing paint. Skins can now react and adapt to changing climate conditions. But under the surface, structure has not changed much. On the interior, environmental innovation has concentrated on MEP systems and material content, which mostly affect health, comfort, and performance and have little impact on visible architecture. Focusing almost exclusively on the skins of buildings and virtually ignoring their bones, sustainable design has overlooked one of the most important determinants of architectural form.

What is sustainable structural design? Many very talented engineers have been silent on this topic. Portuguese engineer Fernando Branco, author of “A Structural Engineer for the 21st Century,” says that the field is just now emerging, its primary goal being to avoid unnecessary depletion of resources by reducing the amount of new material used in buildings. He lists two strategies— increasing longevity by using durable materials and avoiding virgin harvesting by specifying recycled products. As important as these methods are, generally they remain invisible, since they have little or no effect on the image of a building, so they don’t exactly inspire architects accustomed to thinking about form and space. In general, many architects remain uninspired by green building because its most familiar strategies do not represent an aesthetic agenda. In other words, sustainable design seems to be more about sustainability than about design.

The architectural and structural potential of sustainability has yet to be explored fully. If a primary goal is to use fewer resources, one way to accomplish this is to rethink the relationships between material and form. Environmentalist Paul Hawken defines sustainability as “doing more with less,” and the similarity to Mies van der Rohe’s famous mantra “less is more” is ironic, since many green designers see modern architecture as a fundamental source of the problems they are trying to correct. However, like modernism, sustainability can transform new structural technologies into an architectural vocabulary. By inventing methods to optimize the ratio of form and matter, designers can both respect natural resources and create novel geometries that will fulfill sustainability’s architectural possibilities.  

Standard structural members (columns, beams, studs, etc.) typically are over-sized and poorly shaped. The rectangle, the most common shape in construction, is inherently inefficient for carrying loads (and in the case of mechanical ducts, for conveying air). We build orthogonally not to enhance performance but simply because current production techniques such as metal extrusion favor simple forms. The modernist fascination with simple geometry was never about efficient design— it was about efficient fabrication. As Mies himself wrote, “the industrialization of buildings constitutes the core problem of our time.” By embracing plate glass and steel sections, he glorified the production of materials, not their application. In this sense, the modernist edict should have been “form follows industry.”

The stress and strain on a beam is not consistent along its length, so an extruded section is unnecessary and, from a strict environmental point of view, wasteful. Varying the beam’s shape in every dimension is much more efficient for performance. This is exactly what Mark West and his students at the University of Manitoba are doing in their experiments with fabric-formed concrete. While concrete itself is capable of taking on virtually any shape, it is limited by conventional formwork, which is rigid and modular. However, textile molds can achieve forms that are at once more complex and cheaper and easier to assemble. For a typical beam, this technique uses up to 300 times less volume and weight in formwork material and half the concrete of an equivalent rectangular beam. The resulting fluid form, according to West, “places material only where it is needed and uses that material at optimum stress levels at every point along its span.” With such methods, form finally does follow function.

The goal of such techniques is self-sustaining form— geometry that enhances structural and material integrity through the conservation of resources. The idea in itself is not new— nearly two centuries ago, Thomas Jefferson used form to reduce material and increase strength in his famous serpentine brick garden walls at the University of Virginia. The undulating shape required only one layer of brick. And while conventional wisdom holds that the architecture of Antonio Gaudi was merely an expressive skin wrapping simplistic bones, in actuality his understanding of geometry was visionary. The twisted, tree-like columns of the Sagrada Familia, for example, are a tour de force of structure and material. Yet, these inspired examples from history seem to have escaped the notice of most green designers. This is curious, given that many of the best-known environmentally minded architects today worked with or were influenced by Buckminster Fuller, whose concept of “ephemeralization” (minimizing materials) has been abandoned by most of his protégés.

Focusing on material optimization could lead to new structural techniques that may revolutionize architecture altogether. Examples from contemporary design are rare but compelling and mostly come from engineers, not architects. New York structural engineer Guy Nordensen has combined vertical and lateral load systems by experimenting with torqued forms not unlike Gaudi’s. In his projects with Grimshaw, Richard Rogers and Shigeru Ban, Craig Schwitter of Buro Happold has explored ways to optimize spatial volume using alternative materials such as timber thinnings. Grimshaw’s EDEN project in Cornwall, England, may be the most familiar recent example of this strategy. The vast domed botanical gardens in the completed first phase pick up where Fuller’s geodesics left off. Eight interwoven domes built of steel icosahedral space frames and clad in light-weight high-tech foil rely on each other’s “shell action” for strength. The more visually striking education center being developed now with engineer SKM Anthony Hunts creates dynamic stability through novel form— a swirling lattice emulating spiral plant morphology. Grimshaw’s reference to the project as “an exercise in efficiency” is an understatement, for the project possibly represents the future of architecture.