Chicago "affordable housing"

[Ryan Fox]

Yesterday, I learned that numerous former Chicago public school district schools on the South side are going to be auctioned off this fall.  The listing agent believes that the most likely bidders will be Chicago "affordable housing" developers.  Apparently, the most likely use of these properties would be new-build construction for affordable housing.  I'm not sure how such an "affordable housing" program works thru the city.  As someone who owns rental properties on the South side, and very near one the properties to be auctioned, I am concerned about a potential increase in supply of rental units which would drive up vacancy.  However, I've seen very little new construction at all on the South side.  Should I be concerned?  Is there a city program that encourages new-build affordable housing?