However, Kaufman's process reduces waste by up to 75 percent and allows her to bake into her designs an ever-increasing number of green aspects, from materials and finishes to solar panels and energy-monitoring devices. Customers can design their homes online, even downloading software that allows them to "walk through" their designed homes and change specifications in real time. mkDesigns has attracted awards, venture capital funding, and some of the brightest minds in the building industry, all hoping to scale up the company to offer affordable green housing solutions globally.

The new business models don't always work. Consider Nau, Inc., a designer and marketer of outdoor clothing, based in Portland, Oregon. Comprised of refugees from Nike, Patagonia, and other companies, Nau was built from the ground up as a firm that would do things differently and sustainably. It began with the company's mission statement: "To combine the generosity of the human spirit and the power of technology with business innovation to increase shareholder equity, protect the environment, enhance social justice, and provide humanitarian relief worldwide."

Its operation encompassed a range of innovations, including direct distribution, in which it would control its products from concept and design through marketing and sales; an online-offline "Webfront" sales model, in which customers could try on Nau products in stores and either buy them on the spot or, for a 10 percent discount, purchase them online; and customer-directed giving, in which every customer at the time of sale is offered the opportunity to select the nonprofit group of his or her choice to receive Nau's 5 percent contribution of sales.

Nau's vision and values were a great example for companies positioning themselves for the green economy. Notice that I said were. The company lasted only a year, the victim of a challenging financial climate in which to raise working capital. (The Nau brand was eventually acquired by another company.) Even in its demise, it was heralded as "the best kind of failure," in the words of Worldchanging.com's executive editor, Alex Steffen. He called it "a smart, creative, energized bunch of people who saw something wrong with the world, thought they saw how to do something better instead, and went for it with everything they had. In the process, Nau has prepared the ground for a whole crop of innovations and new thinking."

One of Nau's innovations was its messaging. "We are not just looking to make some new clothes," it stated. "We are aiming to redefine what it means to be successful." It communicated clearly, cleverly, and compellingly a deep sense of values without hitting you over the head with its progressiveness. (It evokes one of my favorite company taglines, that of Bronx-based Greystone Bakery, founded by astrophysicist turned Zen Buddhist priest, Bernard Glassman. Founded in the early 1980s, Greystone Bakery hires anyone, including former drug addicts and prisoners, providing training, child care, and counseling, as well as meaningful work. This profitable company, which sells baked goods to some of New York's finest restaurants, proclaims, "We don't hire people to bake brownies. We bake brownies to hire people." Clear, clever, compelling.)

Start-ups with baked-in environmental or socially responsible missions aren't exactly new, but the newest breed is doing more than merely "greening up" a conventional product or service. In some cases, these companies are innovating on not just what they sell but also on the entire value chain.

Consider Shai Agassi. In 2007, the 40-year-old Israeli native left his job as the president of the Products and Technology Group at enterprise software giant SAP to pursue a bold and audacious vision -- to convert an entire country to electric cars powered by batteries that get their energy from renewable energy sources, employing a smart electric recharge grid that covers the entire country. Dubbed Project Better Place, the company began its life with a business plan that called for deploying a vast system of recharging and battery-swapping stations so that they are nearly as ubiquitous as gas stations.