Design standards.

(b) A design standard shall not be adopted if such standard will unreasonably impair the economic or physical feasibility of constructing housing at the minimum densities and with the required incentive housing restriction set forth in sections 8-13m to 8-13x , inclusive. The Commissioner of Housing shall not approve a request for a letter of preliminary or final eligibility under section 8-13q if a proposed design standard will violate the provisions of this subsection.