As per IAS 23, Capitalization of borrowing cost commences when cost for the assets are occurring, Borrowing cost are being incurred & activities needed to prepare asset for use/sale are in progress. And capitalization for the borrowing cost stops when substantially all activities necessary to prepare asset are completed.
Hence, in this case you can capitalize borrowing cost for the period of 2 years. And as per standard, remaining borrowing cost should be recognized as expense in the period in which they incurred. So for next three years remaining cost shall be charged to P&L.