Property, plant and equipment are stated at cost, excluding the costs of day-to-day servicing, less accumulated depreciation and accumulated impairment losses. Expenditure incurred on major inspection and overhaul, or to replace an item, is accounted for as separate components if the recognition criteria are met.

Depreciation is calculated on a straight-line basis, on the difference between the cost and residual value of an asset, over its useful life. Depreciation starts when the asset is available for use. An asset’s residual value, useful life, and depreciation method are reviewed at least at each financial year end. Any adjustments are accounted for prospectively.

The following useful lives have been estimated:

An item of property, plant and equipment is derecognised upon disposal or when no future economic benefits are expected from its use. Any gain or loss arising on derecognition of the asset (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is included in profit or loss in the year the asset is derecognised.

Borrowing costs

Borrowing costs directly attributable to the acquisition, construction, or production of an asset that necessarily takes a substantial period of time to get ready for its intended use or sale are capitalised as part of the cost of the respective assets. All other borrowing costs are expensed in the period they occur. Borrowing costs consist of interest and other costs that an entity incurs in connection with the borrowing of funds.

The group recognises right-of-use assets at the commencement date of the lease (i.e. the date the underlying asset is available for use). Right-of-use assets are measured at cost less any accumulated depreciation and impairment losses, and adjusted for any remeasurement of lease liabilities. The cost of right-of-use assets includes the amount of lease liabilities recognised, initial direct costs incurred, and lease payments made at or before the commencement date less any lease incentives received.

Right-of-use assets are depreciated on a straight-line basis over the shorter of the lease term and the estimated useful lives of the assets, as follows:

If ownership of the leased asset transfers to the group at the end of the lease term, or the cost reflects the exercise of a purchase option, depreciation is calculated using the estimated useful life of the asset. The right-of-use assets are also subject to impairment.

The group also has certain leases with lease terms of 12 months or less and leases of various vehicles and equipment with low value. The group applies the "short-term lease" and "lease of low-value assets" recognition exemptions for these leases.

Right-of-use assets are disclosed in the property, plant and equipment line in the statements of financial position.