Last October, Two and Three Lincoln Centre received gold LEED ratings from the U.S. Green Building Council.

LEED, or Leadership in Energy and Environmental Design, is the most common system used to rate buildings. It “provides a framework for healthy, highly efficient, and cost-saving green buildings,” according to the USGBC, an organization dedicated to promoting sustainable construction projects.

The Preston Hollow towers, first built in 1981 and 1984, are among the highest-rated LEED-certified office buildings in Texas, according to Commercial Property Executive. In total, 139 buildings in the state received LEED certifications last year.

A gold certification, the second-highest award a project can earn, indicates a project scored between 60 and 79 points across nine areas: integrative process, location and transportation, sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality, innovation and regional priority.

Two Lincoln Centre encompasses about 664,000 square feet, and Three Lincoln Centre is about 602,000 square feet. Both buildings were rated using the LEED v4 for Building Operations and Maintenance system.

A 2004 renovation of the towers cost around $10 million, the Dallas Morning News reported. The buildings received a silver LEED certification in 2015.

About six years ago, on-site controllers, flow monitors and weather-tracking technology were installed and added to the existing irrigation system, resulting in a 66% reduction in irrigation water use.

Two and Three Lincoln Centre are located at 5420 and 5430 Lyndon B. Johnson Freeway.