The Butler Health System is refinancing the bonds that were taken out to pay for the tower at Butler Memorial Hospital by up to $115 million.

Anne Krebs, chief financial officer, said the move will save the health system money by taking advantage of lower interest rates.

The system in 2009 took out $126 million in bonds to finance the construction of its seven-story tower, which opened in 2010. The 150,000-square-foot building cost $150 million and included a new entrance off Jefferson Street and a new parking area. The project added 57 beds to the hospital.

When the bonds were taken out, interest rates were about 7 percent, Krebs said. Now, interest rates are 4 to 5 percent.

“It’s a much better interest rate environment,” Krebs said.

She said the system will not know what the exact interest rate will be until it closes on the loan. She also could not say how much money this will save the system, but she said it would be “substantial.”