As blogged on Fast Company, a few years ago, city officials in Phoenix, Arizona, were looking for a way to address the need for more sustainable architecture in their hot, arid environment. Phoenix is the fifth largest city in the United States—and as a result, has a significant environmental footprint. But in 2016, officials debuted a road map designed to transform it into a completely carbon-neutral, zero-waste city. Encouraging ultra-low-energy-usage homes was a natural part of its sustainability goals, but design services can be expensive and slow to procure for the average homebuilder.

Instead, in 2017 the city and the American Institute of Architects’ Arizona chapter devised a design competition called Sustainable Home Design with the aim of offering the winning plan to anyone at no cost. The contest invited local architects to design homes that would achieve a nearly net-zero footprint—meaning it creates as much energy as it uses. More specifically, architects’ submissions had to be rated by the official Home Energy Rating System, or HERS, which measures a single-family dwelling’s energy efficiency. The lower the index score, the more green the home; the design competition asked for a HERS rating of 30, which is 70% lower than most houses.

The winner of the contest, Marlene Imirzian & Associates Architects, went even lower. The studio’s affordable, three-bedroom home, dubbed HOME nz, has an impressive HERS rating of zero. A $100,000 prize went to Imirzian’s firm, and the design is now available for widespread use; the City of Phoenix has made the construction plans for HOME nz available for free to encourage the public to build more eco-friendly homes. “The city of Phoenix has a very visionary sustainability director and department who are looking for leadership for built work in the Phoenix area,” says Imirzian. “[The] goal was to show how simple moves could result in significant [environmental] changes.”

Keep reading this blog on Fast Company