Smith Tower, Seattle’s oldest high-rise, recently earned its LEED Platinum certification from the U.S. Green Building Council. The 273K SF Pioneer Square office building is part of Unico Properties’ portfolio.

The building’s sustainable features include composting of all the paper towels used in the restrooms; garbage containers for compostable waste; an information system that reduces energy while increasing net operating income, which resulted in a 15% reduction in energy use; ongoing recycling efforts; and a maintenance plan that ensures the building is operating at peak performance capacity. High-efficiency boilers, LED lighting and HVAC controls have also been installed.

“It takes effort and leadership to achieve the highest level of LEED certification, especially at a historic and architecturally significant building like Smith Tower,” Unico Properties Vice President, Sustainable and Responsible Investments Brett Philips said in a statement. “We’re pleased to further invest in Smith Tower with our commitment to sustainable stewardship, and we’re honored to achieve this milestone that further solidifies the building’s reputation as a premier city landmark and that offers a superior corporate image for both professional services and creative and technology firms.”

Smith Tower was built in 1914 and was the fourth-tallest building in the U.S. at the time. It remained the tallest building on the West Coast for 50 years. It is protected by both local and national preservation boards.