§ 19. Manner of doing work or acquiring material. The work of construction, reconstruction, alteration, repair or improvement of any state building, whether constructed or to be constructed, may be done by the employment of incarcerated individuals or outside labor or both and by the purchase of materials in the open market whenever in the opinion of the department having jurisdiction over such building, and the commissioner of general services or his or her authorized representative, such a course shall be deemed advantageous to the state, and only upon plans and specifications prepared by the commissioner of general services, but no compensation shall be allowed for the employment of incarcerated individual labor except convict labor.