Existing Approvals Unchanged. Nothing in this chapter shall require
any change in a certificate of appropriateness, building permit, site
plan or zoning variance which was approved before the enactment of
this chapter provided construction shall have been started within
one year from the effective date (as otherwise allowed) of the existing
approval or effective date of this chapter, whichever is earlier in
time, and the project shall be continuously pursued to completion,
otherwise said approvals and permits shall be void.