A Seattle office building that generates its own electricity, collects its own water and composts all human waste from its restrooms earlier this month won the designation as an ultra-sustainable ‘living building’.

To get certified by what is widely viewed as the world’s most demanding green building certification program, the $32.5m six-story Bullitt Center had to pass a year-long examination of its environmental merits to prove it performs as advertised.

Now comes the hard part: convincing skeptics of the financial benefits of constructing more ‘deep green’ buildings like it.

The nonprofit Bullitt Foundation, which built and owns the office building and is headquartered on the top floor, hopes to convince hesitant developers, institutions and governments to invest in similar structures. This may take considerably longer than it took to get certified.

Assigning long term value to deep green buildings is a tricky undertaking, especially because their existence is so new.

Financing has fallen through for multiple projects due in part to a dearth of historical information about comparable properties. The phenomenon of large commercial structures attaining elite Leed Platinum certification or beyond is so recent that researchers haven’t had enough time to assess their shorter term rental and resale performance, says Nils Kok, an expert on green building economics at Maastricht University in the Netherland.

For less strenuous green building projects, however, evidence is mounting that investing in more sustainable structures pays off. In a 2010 study, Kok and colleagues found that buildings that attained Leed Gold status commanded an average premium of 20%.

“We do find that greener actually leads to higher premiums on both the rent side as well as the transaction side,” Kok says.

As a pilot project to determine the technical feasibility of constructing and operating a nearly self-sufficient office building, the Bullitt’s upfront costs ran an estimated 27% higher than those for a comparable structure built to code. “It’s hard to make a project like the Bullitt look good over a period of just five years,” says Denis Hayes, the foundation’s president and CEO.

For universities, museums, municipalities and organizations looking to build more permanent flagship structures, however, Hayes hopes to make the case that a similar investment will provide ample benefits for decades.

In 2014, for example, the Bullitt’s rooftop photovoltaic panels produced roughly 244,000 kilowatt hours of energy while the building used only 153,000 – enough surplus solar energy to power eight homes. If it’s technically possible for a commercial mid-rise in one of the nation’s cloudiest cities to become a net energy producer, Hayes points out, it’s possible nearly anywhere.

The building’s design also slashed its energy demands to less than 40% of a comparable LEED Platinum building and less than 60% of a typical net zero energy building. Based on its better than anticipated energy-saving numbers, a new financial report suggests that the Bullitt could have included fewer solar panels and a smaller steel superstructure and still met its sustainability goals.

Other economic calculations have proven more controversial. In 2014, a separate case study commissioned by the Bullitt Foundation and performed by Ecotrust, a Portland-based conservation organization, calculated that six of the Bullitt’s features – from energy efficiency to rainwater capture – could produce as much as $18.45m in public benefits.

Some of the numbers rely on hotly debated values, such as a maximum price of $200 per metric ton of carbon emissions averted, and the overall benefits will accrue over 250 years. But Hayes says linking a building’s carbon footprint to economic consequences could help change the initial calculus for bankers and developers.

Kok says he appreciates the attempt to quantify the benefits, but he maintains that some of the hypothetical values – particularly the price of carbon – are unlikely to sway the financial sector. “Can you bank on that? Can you underwrite it? I think it’s very challenging,” he says.

Once built, however, Kok says deep green buildings are becoming prized in much the same way that Tesla’s expensive Model S electric car is highly coveted by auto buyers. “These are the new trophy buildings,” he says.

In a separate study, he and colleagues found that law and financial firms, governments and oil and gas companies are among the tenants most likely to lease office space in what’s considered prime real estate. “They want to be in those buildings so badly that they pay a premium rent,” he says.

A large law firm renting space in Washington, DC’s Leed Platinum-certified PNC Place, which opened in 2010, even used its new location as a recruiting tool. The presence of high quality tenants, in turn, can reduce the perception of risk and drive up resale values. In October 2014, PNC Place set a new record for the city when the trophy building sold for $392m, or $1,075 per square foot.

At the very least, conversations about the value of deep green structures are moving into the mainstream, says Ralph DiNola, executive director of the New Buildings Institute in Vancouver, Washington. By his nonprofit organization’s count, the number of verified zero net energy commercial buildings nearly doubled between 2012 and 2015, while the number of buildings deemed capable of eventually reaching that goal nearly quadrupled. DiNola says accumulating evidence also suggests that well-executed deep green designs can minimize or eliminate additional upfront costs, potentially neutralizing financial concerns.

Gary Saulson, director of corporate real estate for Pittsburgh-based PNC Bank, says the new Tower at PNC Plaza, which is slated to open in September, will become the greenest skyscraper in the world – without appreciably adding to the overall construction costs. Unlike the smaller Bullitt, the 33-story tower cannot attain net-zero energy status with existing technology. Nevertheless, a glass ‘double-skin’ facade and a solar chimney will enhance the natural ventilation while other built-in efficiencies could lower water and energy consumption levels by 77% and 50%, respectively.

“We think by building the greenest high-rise in the world, we’re really helping to put Pittsburgh further on the map,” Saulson says. “We really hope that we’re able to put a stake in the ground, and then have someone take it to the next step.”