Any existing or proposed premises having more than 20,000 square feet gross floor area devoted to any use included in the Use Regulation Schedule[1] under commercial and industrial uses shall be considered a major business complex. Any construction, alteration, relocation or change of use resulting in such complex shall be permitted only upon the granting of a special permit by the Planning Board. For the purposes of this subsection, "change of use" shall mean a change in principal use which results in or is accompanied by an increase in the gross floor area of the principal structure of 10% or the addition of at least 10 new parking spaces.