In the case of a housing project consisting of a group of two (2) or more buildings to be constructed on a plat of ground of at least two (2) acres not subdivided into the customary streets and lots, and which will not be so subdivided, where the existing or contemplated street and lot layout make it impracticable to apply the requirements of this chapter to the individual buildings in such housing project, the application of such requirements to such housing project may be changed by the board of adjustment in accordance with the procedure for exceptions, in a manner that will be in harmony with the character of the neighborhood, will ensure a density of land use no higher and a standard of open space at least as high as required by this chapter in the district in which the proposed project is to be located. In no case shall a use or building height or density of population be permitted which is less than the requirement of the district in which the housing project is to be located. (Prior code § 16-35)