(1) In this section and section 380I -
'non-residential unit' has the same meaning that it has in the definition of 'relevant expenditure';
'qualifying lease', in relation to a house, means, subject to section 380I(2), a lease of the house the consideration for the grant of which consists -
(a) solely of periodic payments all of which are or are to be treated as rent for the purposes of Chapter 8 of Part 4, or
(b) of payments of the kind mentioned in paragraph (a), together with a payment by means of a premium -
(i) which is payable on or subsequent to the date of the completion of the refurbishment to which the relevant expenditure relates or which, if payable before that date, is so payable by reason of or otherwise in connection with the carrying out of the refurbishment, and
(ii) which does not exceed 10 per cent of the market value of the house on the date of completion of the refurbishment to which the relevant expenditure relates and, in the case of a house which is a p