Moneys in the Affordable Housing Fund shall be used to provide affordable rental housing for persons earning sixty percent or less of the median household income in the city for the following purposes: provision and expansion of affordable rental housing and suitable living environments in projects, which may include mixed-use, mixed-income projects, having residential units that are principally for persons of low and moderate income through land acquisition for, development of, construction of, and/or capital improvements or rehabilitation to such housing, provided that the funded housing remains affordable for at least sixty years.