The item “permanent improvements” when used in an appropriation act, shall mean and include expenditures for the acquisition, enlargement or improvement of existing buildings and structures (other than repairs), the erection or construction on land of any structure or work which constitutes a substantial addition to real estate, including the total cost thereof in labor, material, supplies, fixtures and any other costs or charges necessary or incident to the completion of the building or structure but not including equipment as herein defined or any expenditure for replacement fixtures or repair parts in connection with the repair and maintenance of property or equipment.