The board shall fix rents, charges, and fees for all projects acquired, constructed, or completed under the terms of this chapter for the use thereof by any persons utilizing the facilities thereof, subject to such contractural obligations as may be entered into by the board and the holders of bonds issued under this chapter. The board is authorized to change rents, charges, and fees from time to time, as conditions warrant. All rents, charges, and fees shall at all times be fixed to yield annual revenue equal to annual operating and maintenance expenses, including repairs and insurance costs and all redemption payments and interest charges and reserve fund requirements on revenue bonds at any time issued and outstanding hereunder, as the same become due.