The world’s first “living” office building is now full to capacity with long-term tenants and working on approval for the final piece of its energy conservation system. Meanwhile, just as the building eliminates the coworking space it initially had, one tenant is opening up its own.

The Bullitt Center at 1501 E Madison was completed in 2013. The building’s claim to the ‘greenest office building’ title comes from its commitment to producing a net zero of energy and water use over the course of every year. The building has 575 solar panels on the roof to collect energy, and a 50,000 square foot cistern to gather rainwater for building use. Each organization in the center gets an energy and water budget based on the square footage it occupies.

The building started out with a coworking space and an assortment of smaller tenants, and has now worked its way up to seven large tenants, most of which are on seven year leases. Bullitt Center spokesperson Brad Kahn said that as a landlord, it is easier to have seven large tenants than 50 small ones. The building has also shut down the coworking space it used to have on the fourth floor, which Kahn said was a stop-gap while the center searched for larger tenants.

One of those tenants is opening up its own coworking space in the building, however. The International Future Living Institute is in the process of moving to a new space in the Bullitt Center, and opened up some of its old digs for coworking as of this month.

The current building tenants are the Bullitt Foundation, Hammer & Hand, Intentional Futures, International Living Future Institute, PAE, Sonos, and the University of Washington Center for Integrated Design. Kahn said that all the tenants are happy with the office, but not every prospective tenant was able to wrap their heads around what working in a green office building requires.

“We definitely had some potential tenants who couldn’t get their heads around, ‘What do you mean our CEO can’t have a parking space?’” said Kahn. Sticking points included the lack of anything but bike parking, the open-plan office that does not include corner offices, and for some, the water budget. For example, Kahn said that a local hair salon badly wanted to be in the building, but ultimately could not keep to the water use that would be required.

While securing large tenants took some time, Kahn said the ones that signed were those committed to the building’s mission. “A lot of the organizations that are tenants in the Bullitt Center chose it because they felt the values of the Bullitt Center aligned with what they were trying to do,” said Kahn. For example, Kahn said design studio Intentional Futures wanted an office space on Capitol Hill with a focus on innovation. PAE consulting and engineering helped to create the center, and Kahn said they chose to become tenants because the building itself was the best sales pitch they could give their clients.

Kahn said so far the center’s systems are working well. In 2015, the building produced 60% more energy from its solar panels than it consumed. While Kahn said it was likely that this number would go up as current tenants hire more employees, he was optimistic. The cistern system, on the other hand, has no impressive stats yet – it is still waiting for approval. Since the collected rainwater is to be used for everything in the building, it is held to drinking water requirements and everything that touches the water must be certified by the National Sanitation Foundation. Kahn said the center is waiting on the results of tests on the solar panels, which the rainwater comes into contact with before it lands in the cistern. Those tests should be complete within the next two months.