The $243 million renovation of the historic Union Depot into a transit hub in St. Paul has earned LEED Gold certification by the U.S. Green Building Council.

The designation by the national organization recognizes Leadership in Energy and Environmental Design, measured by environmental and sustainability best practices.

Owned by the Ramsey Council Regional Railroad Authority, Union Depot initially sought Silver LEED status, but took extra steps to reach the Gold level.

LEED Gold designation is a challenge to attain in an older building, especially one on the historic register," said Rafael Ortega, chair of the Authority, in a statement. "High levels of creativity were required to maintain the historical integrity of the building while modernizing it to be relevant for the next century."

Some of the key elements in the LEED certification included: building reuse; use of salvaged materials; asbestos abatement; construction waste management; lighting controls systems; optimization of natural light; storm water control; efficient landscaping water usage; bicycle station; electric vehicle charging stations; bike/pedestrian enhancements; public transit access; waste management and recycling.

The team that worked on the renovation of the early 20th-century structure included Mortenson Construction, HGA Architects and Engineers, and URS Corp., a transportation design and engineering firm).