NBBJ, an international architecture and design firm whose New York office has been serving a diverse, global portfolio of healthcare, commercial and corporate clients for 25 years, has expanded operations into a new 15,917 s/f home at 2 Rector St. Committed to high sustainability standards and aiming for LEED Gold certification, NBBJ's 60 employees occupy the entire 25th floor in the class A building located between Greenwich St. and Trinity Place. The firm, which employs more than 750 people worldwide, last month relocated from smaller offices at 85 Fifth Ave. near 16th St. "Sustainability is important to us and to our clients across the globe," said Timothy Johnson, an NBBJ principal. "NBBJ mounted a year-long search to identify space that would offer the greatest potential as a sustainable work environment." He said that NBBJ executives wanted to be part of the Downtown revitalization and also wanted to create a sustainable environment that could inspire and stimulate employees and clients.