In Kroon Hall, the toilets flush blue. Built in 2008 for $33.5 million, Kroon, the flagship of the Yale School of Forestry and Environmental Studies, has a koi pond out front containing 25 types of native Connecticut plants that help recycle blue runoff water for the entire building’s use — including the bathrooms.

During every prospective student tour of Science Hill, tour guides bring groups inside Kroon and point to a plaque on the wall. Kroon, it reads, is Leadership in Energy and Environmental Design Platinum-certified — an international designation awarded by the U.S. Green Building Council for “commercial, institutional and residential projects noteworthy for their stellar environmental and health performance.” It is designed to use 81 percent less water and 58 percent less energy than comparable buildings. Over 22 percent of Kroon’s electricity is generated with solar panels.

Kroon is the first stop on the Science Hill tour, and its slotted exterior, like giant window blinds, graces many a Yale brochure. The making of Kroon did not come easy, FES professor Stephen Kellert said. “We had to struggle to convince [the Yale administration] that you can design buildings this way and that it was the right thing to do, not just in terms of the environment, but also in terms of people’s health and well-being inside these buildings.” As Kroon went up, its designers fought to tear down the Pierson-Sage power plant next door, which was spewing steam and periodically leaking oil. It was torn down to give the new green building room to breathe, according to FES associate dean Gordon Geballe.

One of 22 LEED-certified buildings and laboratories on campus, Kroon was conceived in the mid ’90s — more than five years before the LEED certification system was even created. Kellert says the building goes above and beyond LEED standards, and epitomizes the ideals and practices of biophilic design: architecture that connects humans to their natural surroundings.

But Kellert warns that the LEED certification system should not be confused with what he regards as true sustainability: in his view, a combination of environmentally low-impact and biophilic design.

As is typical with green buildings, engineers needed to work out several mechanical and computerized issues during Kroon’s first few years, according to FES director of finance administration Susan Wells. In 2011, she said, during the building’s first full-recorded year, Kroon’s energy consumption was 38 percent higher than its target energy use. This past summer, the facilities team discovered that a relative humidity sensor had broken. The solar hot water system meant to heat the building’s water still has yet to work properly; a $40,000 repair is in the works.

Kellert attributes the failure of the building to reach its energy efficiency target to professors and students using the library after hours and on weekends — proof that students and faculty loved the building so much they didn’t want to leave. But, according to Wells, a computer programming error — which has since been fixed — caused the building to consume more energy than it should. Since the fix, the building has performed better than expected.

“I’m always a little skeptical if the building is living up to its height,” FES associate dean Gordon Geballe said. “I always think there are things we can do to make it better.” As people using Kroon Hall become more conscious of the building’s energy-saving mechanisms, he added, Kroon’s efficiency will continue to improve.

Former FES dean James Gustave Speth said he believes the Kroon project was a “powerful learning process” for Yale. A champion for Kroon’s construction, Speth said the building helped inspire a campus commitment to the environment, and helped spur the creation of the Office of Sustainability in 2005.

But Geballe said he is unsure if Kroon has inspired the rest of campus as much as its creators had expected. He said Kroon proved that Yale is capable of creating LEED certified buildings, but he questions whether Kroon’s platinum rating has set a standard for the future. At present, according to the 2013–16 Yale Sustainability Strategic Plan, Yale projects are only required to meet LEED Gold, not Platinum, Standard Certification.

James Ball FES ’16, who has inspected and certified LEED buildings across the country, said that while he and others would love to see a commitment by Yale to a standard of biophilia, he believes it is reasonable for the campus to set LEED standards as their goals.

Robert A.M. Stern, dean of Yale School of Architecture and architect for the new residential colleges set to open in 2018, asserted that new residential colleges will be part of Yale’s renewed commitment to sustainability. In designing the new colleges, Stern said his team has carefully selected materials that are locally sourced or recycled whenever possible. He added that the designs take advantage of low-tech solutions like allowing for the optimal amounts of sunlight into the courtyards.

Stern noted that over the years creating energy-efficient buildings at Yale has become easier as Yale’s clientele becomes more sustainability-minded. He added that more thought goes into the long-term cost of buildings now compared with 40 or 50 years ago, when the public was enamored of architectural shapes that did not lend themselves to long-term efficiency.

Although Kroon is still the greenest building on campus and may be for some time, Kellert believes its construction paved the way for a more green and biophilic-minded Yale. Ginger Chapman, director of Yale’s Office of Sustainability, said new standards for LEED, implemented in Spring 2014, will correct many of the issues in LEED certification and set the standard for Yale architecture in the future.

“There was a constant tension because we were always pushing the envelope on what we wanted to do,” said Kellert. “We always saw [Kroon] not just as a building for the Forestry School but … as a way for the University to become far more aware, appreciative and committed to sustainable design and development across campus. I do think the building had that effect.”