n(A) An application for a certificate of appropriateness shall be evaluated on a sliding scale, depending upon the designation of the building, structure, site or object in question.  The certificate shall be evaluated on the following criteria: n(1)        Most careful scrutiny and consideration shall be given to applications for designated landmarks; n(2)        Slightly less scrutiny shall be applied to properties designated as key contributory within an historic district; n(3)        Properties designated contributory and non-contributory within an historic district shall receive a decreasing scale of evaluation upon application; n(4)        The least stringent evaluation is applied to the environs area of a landmark or historic district.  There shall be a presumption that a certificate of appropriateness should be approved in this category unless the proposed construction or demolition would significantly encroach on, damage, or destroy the landmark or historic district. If the Commission denies a certificate of appropriateness in this category, and the owner(s) appeals to the City Commission, the burden to affirm the denial shall be upon the Commission, the City or other interested persons.