(a) The first ordinance enacted by a municipality to designate any historic properties shall provide for the creation of an historic properties commission and for the termination of the historic properties study committee or committees. The historic properties commission shall administer the provisions of this part relative to all historic properties then or thereafter designated by the municipality and, relative to such historic properties, the commission shall have all of the powers and duties that historic district commissions have over historic districts pursuant to part I of this chapter except as is otherwise provided in this part. A municipality may designate an historic properties commission to administer historic districts in accordance with part I of this chapter in the event that no historic district commission exists when the historic properties commission is created. A municipality may designate an existing historic district commission to administer historic properties in accordance with this part.

(b) The historic properties commission may from time to time, in accordance with § 7-147q, initiate the designation of additional historic properties or the enlargement of the boundaries of an existing historic property.