By Roger K. Lewis
Saturday, March 18, 2006
Today just about all architects put sustainability near the top of the list of project design goals. Sustainability is on practically every conference agenda related to design, planning, construction and real estate development. But what does it mean to create sustainable architecture?
Dictionaries cite the adjective "sustainable" and the noun "sustainability" only after offering several definitions of the verb "sustain": to support, to keep up, to keep going, to provide for by furnishing means or funds.
Does this mean that a sustainable building is one with a skeleton that will prevent it from falling down, a building with technical systems that keep it functioning well year after year, or a building with revenue and expenses that continue to meet its owner's funding and investment objectives?
Architecturally, the sustainability ideal lies elsewhere. It is about conserving energy and material resources, safeguarding the health of occupants, and protecting and enhancing the natural environment. Sustainability in architecture means minimizing not only the waste and pollution generated by buildings, but also that attributable to their construction.
Architects are not alone. Sponsors of cultural, commercial and government projects increasingly seek silver, gold or platinum LEED ratings for their buildings -- LEED stands for Leadership in Energy and Environmental Design.
LEED ratings are calculated by adding up points earned for favorable site and building design. Those characteristics include brown-field redevelopment; access to existing transit and utilities; use of locally available or minimally transported materials as well as recycled or naturally replenishable materials; avoidance of materials that emit noxious gases or particles; use of solar energy, daylight and natural ventilation; recapture of waste heat; capture of rainwater and recycling of wastewater; efficiency of building form; tightness and insulating efficacy of building skin; and ecologically sensitive landscaping.
Increasing numbers of architects have studied and taken courses to become LEED-certified under a program administered by the U.S. Green Building Council.
But high LEED ratings aren't the only reasons for being green and environmentally sensitive. With energy prices soaring, economic motivation is greater than ever before.
A high LEED rating, however, does not guarantee great architecture. Energy-efficient buildings can be ugly. Buildings with green roofs can be ugly. Indeed, the nature of LEED assessment avoids making value judgments about a building's visual or symbolic qualities.
Nevertheless, sustainability has artistic implications. Architects who aspire to garner high LEED ratings do not have to abandon aesthetic exploration and invention.
After all, making buildings comfortable, fireproof, earthquake-proof and accessible to the disabled has not stopped architects from designing beautiful structures. Why should designing for sustainability be an impediment to visual and intellectual delight?
In fact, the language of sustainable design expression is rapidly developing, although its grammar and vocabulary are still evolving.
Some tactics for making buildings sustainable, primarily involving material specifications and engineering systems design, are important, but often not visible. What is apparent are building geometries and exterior enclosures, clearly the most visible manifestation of sustainability.
Because energy conservation is a major goal of sustainability, and because a building's energy consumption is determined to a great extent by volume and cladding characteristics, architects must still concentrate design attention on building form and facades.
Generally, more compact buildings require fewer materials, which means less energy invested in construction and, with reduced exterior surface, less energy to heat and cool buildings after construction.
At one extreme is the sphere, the most efficient form because its skin-to-volume ratio is lower than any other geometric shape. This suggests that for optimum sustainability, blob-like architecture might be the wave of the future. But blobs are less than ideal for accommodating most building functions or for harmonizing with adjacent structures.
Conversely, geometrically distended, multifaceted or fragmented buildings are the least efficient. They have greatly increased exterior surface area and skin-to-volume ratios, which adds significantly to costs, in dollars and energy, for construction and operation.
Accordingly, rectilinear volumes are more prevalent and practical, since much of the fabricated world is based on straight lines and right angles. Sometimes architects transform rectilinear volumes using circular and spherical geometries -- for instance, the National Museum of the American Indian -- although usually not for reasons of sustainability.
No matter how efficiently configured, a compact form remains aesthetically mute until its exterior walls are composed. And facades continue to offer architects their greatest opportunity for developing new modes of artistic expression based on sustainability-related composition.
Such opportunities are numerous: employ visually diverse cladding materials and textures; control, filter, reflect or transmit daylight to the interior; shade summer sun but admit winter sun to provide heat; cast ever-changing shadow patterns; allow natural ventilation; exploit views to and from the interior; and create overall window and door patterns, juxtaposing transparency and opacity, to animate and impart order to facades.
Yet few of these moves are new. Ancient Greek and Roman builders, Renaissance and Enlightenment architects, and architects of the Modern movement understood these moves long before energy was an issue and long before anyone used the word "sustainability."
Designing for sustainability merely continues an ageless architectural tradition, based on the idea that "necessity is the mother of invention." Thus pursuing sustainable design is not only the ethical and, in the long run, the most economical thing to do, but also the smart thing to do to make buildings look and perform better.
Roger K. Lewis is a practicing architect and a professor of architecture at the University of Maryland.