To the extent that these services are available, school districts shall arrange for the preaudit and postaudit of school buildings by investor-owned or municipal utility companies or by independent energy audit companies or organizations which are recognized by federal or state regulated financial institutions. The preaudit shall identify the type and amount of work necessary to retrofit the buildings and shall include an estimate of projected energy savings. The postaudit shall be conducted upon completion of the retrofitting of the school buildings to ensure that the project satisfies the recommendations of the preaudit.