Authorizes SHPD to conduct a phased review of a proposed project on private property under certain circumstances. Amends the process and deadlines by which SHPD must provide written concurrence or non-concurrence for proposed projects on private property or certain projects that require state or county approval for entitlement for use, after which concurrence may be assumed and the project may move to the next step in the compliance process. Amends the conditions under which a proposed project on an existing privately owned single-family detached dwelling unit or townhouse that is over fifty years old shall be subject to section 6E-42, HRS. (CD1)