Ever since the invention of the skyscraper, the contest between cities to see who could be home to the tallest building has had a symbolic potency on par with the space race. Now two of America's "greenest" cities are engaged in a whole new sort of architectural cage match, and in the process they're inverting the dated priorities of the profligate, fossil-fuel soaked 20th century and instead designing buildings based on the harmonious functioning of ecosystems.
Within weeks of each other, groups in both Seattle and Oregon announced that they were building the world's "greenest" office building. These structures go way beyond the U.S. Green Building Council's LEED Gold standard, aiming instead for the much more stringent and results-oriented Living Building Standard.
The defining feature of the Living Building standard is that, true to its name, a building must behave like a living organism. And not just a wasteful, unsustainable individual, but an entire, self-contained ecosystem. A Living Building must produce all of the electricity it uses, and collect 100 percent of the water it consumes. Both requirements mean that a living building must be extremely efficient with both energy and water in addition to being especially good at collecting both.
So far only three buildings in the world have attained Living Building certification , in part because a structure's performance must be measured for a full year to establish its bona fides. So it will be some time until we know whether--and by what measure--Seattle or Oregon is home to the "world's greenest building."
Here are the contenders:
The Cascadia Center for Sustainable Design  in Seattle will be six stories tall and include 50,000 square feet of usable space.
The Oregon Sustainability Center  will include four different kinds of solar panels , including ones embedded in its windows that allow visible light to pass through while also generating electricity.
What's perhaps most interesting about these buildings is that the their biomimetic properties mean that they have a great deal in common, despite having been designed independently of one another.
For example, you won't see many skyscrapers contending for Living Building status because the ratio of roof space to a building's interior volume affects whether or not it can be energy self-sufficient, especially if it's relying on solar panels. That's one reason why the Cascadia Center is only six stories tall, and the Oregon Sustainability Center just seven. Just like biological organisms have their proportions limited by their environment, these buildings need to be relatively compact and close to cubical in shape. The structure with the lowest ratio of surface area to volume in nature is a sphere, after all.
Both buildings use geothermal, ground-source heat pumps to accomplish a significant portion of their heating and cooling. This makes sense--unless both were built to a "passive house" standard, which is quite difficult with commercial buildings--there simply isn't any other way to keep their internal environments comfortable. In this way they resemble reptiles basking on warm or cool rocks to help maintain their internal temperature.
Rainwater catchment and an underground reservoir are also features of both buildings, and in this way they reproduce plants' capacity to store water.
The most important feature that these buildings have in common is their external climate. It's no mistake that Portland and Seattle are contending for the world's greenest buildings, because their temperate climates mean that locations in the Pacific Northwest are among the least expensive in the world to construct "net-zero energy" buildings that can produce all the electricity they need.
Indeed, a financial study conducted in 2009 by a team of architectural and building firms estimated that the price premium (versus a conventional building) for a mid-rise office Living Building is around 26 percent in a climate like that found in Portland, Oregon. But the same building would cost 32 to 40 percent more than a conventional building in an especially hot or cold climate like Phoenix or Boston. (You can see a PDF of the cost comparison matrix here .)
Just like organisms, buildings that are energy and water self-sufficient have to gather and expend more energy when they live in harsh climates. The larger lesson of the Living Building challenge is one we've forgotten since the surfeit of fossil fuels made heating and air conditioning the norm: Some parts of the world are simply easier to live in than others.
[Images: Courtesty Cascadia Center for Sustainable Design and Oregon Sustainability Center]