4. For premises containing more than four (4) dwelling units, in consideration of
4. For premises containing more than four (4) dwelling units, in consideration of the increases in the otherwise permissible density of population or intensity of a particular use authorized pursuant to this Section 8.2, at least ten percent (10%) of the dwelling units, in no case less than one (1) unit, shall be deed restricted in perpetuity as "Affordable Units" as defined in the applicable regulations of the Department of Housing and Community Development.