Property, plant and equipment
Items of property, plant and equipment are stated at cost less accumulated depreciation and any accumulated impairment losses.
Depreciation is calculated to write off the cost of items of property, plant and equipment less their estimated residual values using the straight-line method over their estimated useful lives, and is ultimately recognised in profit or loss. Leased assets are depreciated over the shorter of the lease term and their useful lives unless it is reasonably certain that the Group will obtain ownership by the end of the lease term. Freehold land is not depreciated. The estimated useful lives of items of property, plant and equipment is 3–20 years and for buildings is 20–50 years.
Assets in course of construction are not depreciated until they are available for use.
Depreciation methods, useful lives and residual values are reviewed at each reporting date and adjusted if appropriate.
Finance costs relating to the purchase or construction of property, plant and equipment and intangible assets that take longer than one year to complete are capitalised based on the Group weighted average borrowing costs. All other finance costs are expensed as incurred.