A zoning ordinance may include districts for planned developments, provided that an ordinance providing for approval of subdivisions and site plans by the Planning Board has been adopted which incorporates therein the provisions for such planned developments in a manner consistent with N.J.S.A. 40:55D-37 et seq. The zoning ordinance shall establish standards governing the type and density or intensity of land use in a planned development. Said standards shall take into account that the density or intensity of land use otherwise allowable may not be appropriate for a planned development. The standards may vary the type and density or intensity of land use otherwise applicable to the land within a planned development in consideration of the amount, location and proposed use of common open space, the location and physical characteristics of the site of the proposed planned development and the location, design and type of dwelling units and other uses. Such standards may, in order to encourage flexibility of housing density, design and type, authorize a deviation in various residential clusters from the density or intensity of land use established for an entire planned development. The standards and criteria by which the design, bulk and location of buildings are to be evaluated shall be set forth in the zoning ordinance, and all standards and criteria for any feature of a planned development shall be set forth in such ordinance with sufficient certainty to provide reasonable criteria by which specific proposals for planned development can be evaluated.