18.—(1) Subject to paragraph (4), regulation 17(1)(a)(i) does not apply in relation to a display energy certificate which is displayed by an occupier of a building at any time before it has been in occupation of the building for 15 months.
(2) Regulation 17(1)(a)(ii) does not apply in relation to a display energy certificate which is displayed by an occupier who—
(a)entered into occupation of the building before 6th April 2008; or
(b)entered into occupation on or after that date but did not have an energy performance certificate complying with regulation 11 made available or given to it.
(3) In the period up to and including 3rd January 2009, where neither regulation 17(1)(a)(i) nor (ii) applies in relation to a display energy certificate, the duties in regulation 16(2) do not apply.
(4) Where on 4th January 2009—
(a)the occupier of a building has been in occupation for less than 15 months; and
(b)by virtue of paragraph (2) regulation 17(1)(a)(ii) does not apply,
the operational rating specified for the purposes of regulation 17(1)(a)(i) may be calculated over the period in which the occupier has been in occupation.