1. Bonds issued by the board of public buildings pursuant to the provisions of sections 8.570 to 8.590 may be refunded, in whole or in part, at any time whenever the board of public buildings determines that such a refunding is in the best interest of the state or the board of public buildings.

2. For the purpose of refunding any bonds issued hereunder, including refunding bonds, the board of public buildings may make and issue refunding bonds in the amount necessary to pay off and redeem the bonds to be refunded together with unpaid and past due interest thereon and any premium which may be due under the terms of the bonds, together also with the cost of issuing the refunding bonds, and may sell the same in like manner as is herein provided for the sale of bonds being refunded. Refunding bonds issued pursuant to sections 8.500 to 8.590 shall be payable in not more than forty years from the date thereof and shall bear interest at a rate not to exceed fifteen percent per annum.

3. The refunding bonds shall be payable from the same sources as were pledged to the payment of the bonds refunded thereby and in the discretion of the board of public buildings may be payable from any other sources which pursuant to sections 8.500 to 8.590 may be pledged to the payment of revenue bonds issued hereunder. Bonds of two or more issues may be refunded by a single issue of refunding bonds.