12. (1) A planning authority shall determine, as soon as may be after it is entered on the register, and at least once every 3 years thereafter, the market value of a vacant site by estimating or causing to be estimated the price which the unencumbered fee simple of such site would fetch if it was sold on the open market on the date of the determination in such manner and in such conditions as might reasonably be calculated to obtain for the vendor the best market price for the site.

(2) The market value of the vacant site shall be estimated by the planning authority and it shall authorise a person it considerssuitably qualified for that purpose to inspect the site and report to it the value thereof and the person having possession or custody of the site shall permit the person so authorised to inspect at such reasonable times as the planning authority considers necessary.

(3) Where a person authorised under subsection (2) is not permitted to inspect a property for the purposes of providing an estimate, he or she shall make an estimate of the market value of the site based on his or her knowledge of the site and property and the prevailing local market conditions.

(4) Where the planning authority has determined the market value of a vacant site it shall enter particulars of the determination in the register (together with the date of entry in the register), and give written notice to the owner of the vacant site of the valuation or the revised valuation, as the case may be, which it has placed on the site and inform the owner of his or her right to appeal under section 13.