Construction has started on the first of six new affordable housing units to be built in East New York.Officials say rents in the new apartments will range from $600 to $920 a month. The four and-a-half-story apartment buildings are the third phase of affordable housing being built by a number of organizations including the East Brooklyn Congregation. Since 1983 they have built 2,900 affordable homes across Brooklyn. To qualify for one of the new units, officials say an individual cannot earn more than $26,400 a year, and the income for a family of four cannot exceed $37,680. Residents of Community District 5 will be given preference for half of the apartments.