Part of OnEarth's Answers from the Past month, in which our contributors explore how contemporary thinking on sustainability has been influenced by wisdom handed down to us from previous generations. Read more here.
The greenest commercial building in the world sits on a slope near Seattle’s Capitol Hill district, topped by what looks like a high-tech wimple—the Flying Nun meets an attractive cube of glass and concrete. The ecclesiastical headgear is, in fact, a canted array of 575 high-efficiency photovoltaic solar panels. Combined with 26 geothermal wells, the panels will make the six-story Bullitt Center a net-zero energy user—that is, it will produce as much energy as it uses over the course of a year. And by harvesting and purifying the drizzle that falls from the Pacific Northwestern sky, the Center is also a net-zero user of water.
Many residential and commercial buildings collect and store rainwater in barrels, to be used for landscaping and gardening. In an era of diminished freshwater supply, that’s smart, but nothing new. The Bullitt Center’s commitment to net-zero water, however, is the equivalent of rain barrels on steroids. The roof shunts rain to a 56,000-gallon cistern in the basement. From there, the screened and filtered water will be used for irrigation and cleaning and to “flush” composting toilets. These appliances use about a tablespoon of water to create a foamy transport medium, which sends human waste to the basement, where it’s mixed with sawdust and breaks down in enclosed (no smell!) vessels. Another portion of the rain water will be made potable by running it through a series of filters, then disinfecting it with ultraviolet light. Activated charcoal filters will strip chlorine, added to keep water bacteria-free while it’s in the pipes, at the spigot. At last, this water will be ready for use in sinks, showers, and water fountains. Presumably it will make excellent espresso.
But that’s not all. Gray water, collected from the building’s sinks and showers, will be pumped to the third floor, where it will trickle slowly through a constructed wetland before it sinks, through street-level plantings, into Seattle’s aquifer. “We’ll be infiltrating about 65 percent of what we collect,” Brad Kahn, the Bullitt Center’s communications director, says. “That’s the amount of rain water that used to be returned to the earth before Europeans settled here, back when this was a Douglas fir forest.”
Owned by the environmentally oriented Bullitt Foundation, the Bullitt Center is undeniably modern. But it’s also delightfully retrograde, eschewing both the electrical and water grids and relying, instead, on its own powers of creation, transformation, and degradation—much as small pre-industrial villages did. Of course, those villages were far smaller, and less demanding of resources, than today’s communities, and therein lies the challenge. If the Bullitt Center can rigorously document its hyper-local sufficiency over a one-year period, it will become the first commercial building to earn certification from the Living Building Challenge, a performance-based standard for sustainability that goes well beyond the demands of the better known Leadership in Energy and Environmental Design (LEED) standard.
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Saving rainwater for residential or commercial use makes sense in arid regions: it shrinks the demand on municipal water supplies and saves property owners money. Without further treatment, rainwater can be used for flushing toilets, washing clothes and cars, and watering lawns and gardens. Rain barrels and their larger-scale counterpart, cisterns (big underground vaults), can also reduce energy use and the carbon emissions associated with pumping, treating, and distributing water in a centralized system. According to the Environmental Protection Agency, reducing the demand for treated tap water by 10 percent could save the nation enough energy to meet its entire residential, commercial, and industrial demand for 30 days.
But wetter cities are also encouraging rainwater collection these days—mostly to protect their waterways from the ravages of something known as “combined sewer overflows.” CSO events occur during rainstorms, when wastewater treatment plants reach capacity and dump raw sewage directly into nearby creeks, lakes, and harbors. Joining the sewage is rainwater that sluices off parking lots and roads polluted with heavy metals, oil, and street litter. The combined insult jeopardizes human health, degrades ecosystems, and repulses waterfront visitors.
To address these issues, cities are loosening their building codes and offering rebates and technical assistance for so-called green infrastructure that retains storm water and releases it slowly to the earth. Rain barrels—like their hydrophilic cousins bioswales, rain gardens, and green roofs—not only protect rivers, lakes, and harbors from polluted deluges, they also restore local aquifers, mitigate floods, and reduce the amount of water headed to centralized wastewater plants.
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With its closed-loop water system, the Bullitt Center sends nothing to Seattle’s wastewater treatment plant or into its harbor. That’s helpful, because in 2012, Seattle discharged 154 million gallons of raw sewage and polluted runoff into local waterways. But the building is also reducing its pull on city reservoirs by rendering its rainwater potable.
And now you may ask: why, in a city that gets a decent 35 inches of rain a year, does this even matter? Because Seattle’s population, currently about 635,000, is expected to rise by one to two million people in the next 20 years, and because the climate is changing. The city is likely to see more frequent and longer periods of drought, while warmer winter temperatures mean precipitation will more likely fall as rain, instead of snow. Rain will immediately increase the flow of rivers: that water will run to the sea if not captured.
But it’s also delightfully retrograde, eschewing both the electrical and water grids and relying, instead, on its own powers of creation, transformation, and degradation—much as small pre-industrial villages did.
And so Seattle is considering its options. The city could hang onto that influx by building a new reservoir—considered unlikely, as all the good spots for water storage are already inhabited. Or, according to some visionary planners, it could build a distributed system of catchment cisterns, on a neighborhood or district scale, to capture water, treat it to the appropriate level for use, then reuse and recycle it on site.
If harvesting and purifying rainwater is such a great idea, why aren’t other urban buildings, or even neighborhoods and cities, doing it? A few, in fact, are: a development in the Netherlands, with 250 housing units and commercial space, is net-zero water, as are buildings on numerous campuses in the United States (at U.C. Davis, at Pittsburgh’s Phipps Conservancy, and at Google’s new Bayview complex, for example). Approximately 140 projects in eight countries are currently working to meet the Living Building Challenge.
But obstacles, as one may guess, abound. Existing buildings tend to be on the grid already—hooked up to community water systems that provide good, cheap water (the United States has among the cheapest water rates in the world). There are also federal, state, and local regulatory hurdles to leap, permits or variances to obtain, and employees to train. (If you form your own “water district,” no matter how small, you’ve got to meet Safe Drinking Water Act standards, which means someone needs to be certified to run the system.) And then there’s the price tag: the Bullitt Center’s construction costs were 20 percent higher than those for a comparably sized conventional building. (On the upside: it will have no electric or water bills, and it was designed to last 250 years.)
Kahn admits that distributed water systems that rely on rain aren’t for everyone. It would be tough to do net-zero water in the desert. Nor would net-zero water work in places where downstream cities depend on the flow that upstream cities return to rivers from their centralized wastewater treatment plants. But such systems could work, in many locations, at the scale of a city block or district.
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I have to admit, I have a hard time imagining cisterns working in a place like New York City, my home town, which gets 48 inches of rain a year, houses 8 million people, and runs through more than a billion gallons of water a day. Ninety percent of our water comes to us from the upstate Catskill Mountains region, via shared pipes, tunnels, and aqueducts, and most of the system is gravity fed. Why mess with a good thing?
Because—wait for it—the population is growing, and the climate is changing. It doesn’t take a catastrophist to recognize that a densely populated city that relies on water imported from 100 miles away is neither self-sufficient nor resilient. The system, parts of which are more than a century old, has many potential failure points and already leaks up to 35 million gallons a day, enough to slake half of Pittsburgh’s daily thirst. As the world warms, New York City, which is already leading on climate adaptation, needs to look at backup systems. “Rainwater is a great untapped resource,” says Cecil Scheib, director of advocacy for the New York chapter of the U.S. Green Building Council, “and fostering resiliency is a huge issue post Sandy.”
New York isn’t likely to meet all its needs with rooftop water: the ratio of roof to people doesn’t pencil out (costs and current regulations aside). But a distributed network of rainwater catchment, in conjunction with the existing grid, is worth considering, especially in the case of new construction. It doesn’t have to be an either-or scenario. Such systems can help extend existing infrastructure without drawing down aquifers or streams, and simply collecting rain in barrels or cisterns—even if one has no intention of drinking it—can help reduce flooding.
The Bullitt Center, which opened on Earth Day of 2013, is a demonstration of what’s possible and an inspiration for overcoming the substantial financial, regulatory, and cultural barriers to sustainable design. Planners and lenders, architects and builders, regulators and code enforcement officers are watching closely to see how things shake out. Can these systems be emulated elsewhere? Will the building eventually earn out its additional costs? The answers might not all be yes, but at least the Bullitt Center has dared to stick its neck out and to very publicly investigate. Anyone concerned with the future of design—with the future, period—should be grateful.
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