a. (1) In any case where an applicant for a permit from the department of buildings to construct, reconstruct, alter or demolish any improvement on a landmark site or in an historic district or containing an interior landmark, or an applicant for a special permit from the city planning commission or the board of standards and appeals authorizing any such work pursuant to article seven of the zoning resolution, or amendments thereof, files a copy of such application or amended application with the commission, together with a request for a certificate of no effect on protected architectural features, the commission shall determine:
(a) whether the proposed work would change, destroy or affect any exterior architectural feature of the improvement on a landmark site or in an historic district or any interior architectural feature of the interior landmark upon which said work is to be done; and
(b) in the case of construction of a new improvement, whether such construction would affect or not be in harmony with the external appearance of other, neighboring improvements on such site or in such district. If the commission determines such question in the negative, it shall grant such certificate; otherwise, it shall deny such request.
(2) Within thirty days after the filing of such application and request, the commission shall either grant such certificate, or give notice to the applicant of a proposed denial of such request. Upon written demand of the applicant filed with the commission after the giving of notice of a proposed denial, the commission shall confer with the applicant. The commission shall determine the request for a certificate within thirty days after the filing of such demand. If a demand is not filed within ten days after the giving of notice of the proposed denial, the commission shall determine such request within five days after the expiration of such ten-day period.
(3) In the event of a denial of such a certificate, the applicant may file with the commission a request for a certificate of appropriateness with respect to the proposed work specified in such application.