this could disincentivise investors from land banking and open up more available land for affordable housing for the urban poor this and other fiscal measures for example providing incentives for development of infill sites could also augment the overall supply of affordable housing previously builders could exchange money or land instead of setting aside up to of new developments for social or affordable use a provision under part v of the planning act and therefore some developers have been able to build the social portions of new developments elsewhere however now social units must be predominantly on site making it mandatory for developers to set aside up to of new developments for social use