Organizers of The Leonardo at Library Square revealed its renovation design that calls for the structure to be environmentally sustainable. And one element of the green design will be front and center: an evaporative cooling tower at a new entrance.

In addition, the exterior will become a canvas, with banners hanging over the building's defining concrete panels.

It's all part of the Leonardo's mission, said executive director Mary Tull: to teach. In this case, it will be a "showcase for sustainable operations."

The renovation of the city-owned building will cost $13 million. The bulk of the cost - $10 million - will be paid by taxpayers, who agreed in 2003 to raise property taxes for the renovation. The Leonardo must raise the remaining $3 million. It hopes to gain federal grants and historic tax credits. The city also has given the Leonardo another $750,000, as long as it raises a matching amount.

The design is a scaled-back version of an earlier scheme that would have added 11,000 square feet of space. But that would have cost $18 million. The funds aren't there and neither is the time: It would cost $100,000 each month the project is delayed for fundraising.

"The capacity to raise millions more for an addition is not now," Tull said, adding that the new design will allow an expansion in the future.

The building needs to be upgraded to withstand earthquakes. The solution is four walls that will be placed inside the structure. The previous plan called for an external corner bracing system that historic preservationists opposed because it would have altered the concrete panels.

Mayor Rocky Anderson has approved the design, as have preservationists, according to the Leonardo.

Construction will start in 2007 and it will open in spring 2009, a year later than initially projected.

By next month, Tull will be able to reveal the exhibits and galleries planned for the inside. The partners include Utah Science Center, Global Artways and Center for Documentary Arts.

hmay@sltrib.com