Studies have shown that the addition contained approximately 50 percent fewer airborne microbes than a plant-free section of the home. The building maintains a comfortable humidity, ranging from 40 to 60 percent. This sustainable design, operational since 1989, closely balances the symbiotic relationship of plants, their root-associated microbes and humans. Ventilation within this area of the building is reduced and the air re-circulated. As wastewater slowly passes underneath the plants in the hydroponic planter system, it is purified.
Any excess wastewater is gravity-fed to the exterior landscaping for further treatment.
Staff members seek the prime location of offices near the atrium planters and there have been no IAQ complaints in the building. This first of its kind public building has operated for many years with only minor problems. New built-in modules are currently in the design phase. The use of interior plants to create a sustainable ecological system within hermetically sealed buildings is gaining acceptance within the building industry and the general public. Progressive scale-up of indoor ecosystem technology has answered many of the skeptics concerns.