As used in this act, unless the context clearly requires otherwise, the following words shall have the meanings ascribed to them in this section:
(a) "Public building" shall mean and include any building or structure determined by the board of county commissioners to be necessary to the county for any public county purpose.
(b) "Improve" shall mean and include alteration, repair, reconstruction, remodeling, furnishing, equipping, extending, adding to, enlarging or any other work which will enhance, extend or restore the value or utility of the public building.