The Empire State Building's 6,500 windows will be retrofitted as part of an energy overhaul designed to reduce the iconic skyscraper's energy use by 38 percent.

Milwaukee's Johnson Controls, which is overseeing the Empire State Building retrofit project, with a team of energy efficiency experts including the Clinton Climate Initiative, Jones Lang LaSalle, and Rocky Mountain Institute, announced Wednesday that California's Serious Materials was chosen for the massive window project.

Serious Materials will reuse all the existing windows in the 102-story New York City landmark and create super-insulating glass units.

During the nine-month construction period, Serious will occupy a 5,000 sq. ft. space in the building, which will serve as the project's processing and production area. To reduce noise, the company will install its QuietRock soundproof drywall product in its working space. The window retrofitting is expected to begin within the next 45 days.

"When we heard that retrofitting the dual-pane windows was a key component of the cost-efficient upgrade program, we went to work and came up with a solution never before attempted," Kevin Surace, chief executive officer of Serious Materials told Contract Magazine.

"Most people throw out the glass and start anew," Surace said. "It wasn't cheaper to do this but it was the right thing for the planet."

The super-insulating windows will reduce energy use and produce savings "that will payback in three years," said Iain Campbell, vice president and general manager, Global Energy & WorkPlace Solutions, Johnson Controls, in a statement.

Surace said he's seen a 50 percent growth trend in the last few years toward retrofitting initiatives.

"We expect to use this model with other major efficiency projects throughout the world with customers who want to save real money in their buildings," he said.

The overall greening makeover of the Empire State Building will cost $500 million by the time it's completed in 2013. Other measures in the eight-part project include upgrading the air, water and lighting systems as well as tenant energy management.

The project is expected to save $4.4 million per year in energy costs and save 105,000 metric tons of carbon dioxide over the next 15 years.

According to Serious Materials' Web site, the Empire State Building will be more energy efficient than 90 percent of all office buildings and use half the energy per square foot of an average building.

"The Empire State building represents a model to others who may look to emulate what is being done at this landmark building from an energy efficiency standpoint," Campbell said.