Recognition and measurement

• Property, plant and equipment: assets are recorded at cost less accumulated depreciation. Cost includes expenditure that is directly attributable to the acquisition or construction of the asset. Finance costs directly attributable to the acquisition or construction of qualifying assets are capitalised. Subsequent costs are included in the asset’s carrying amount or recognised as a separate asset, as appropriate, when it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. All other repairs and maintenance are recognised in profit or loss as incurred. The gain or loss arising on disposal or retirement is recognised in profit or loss. The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at the end of each reporting period. An asset’s carrying amount is written down immediately to its recoverable amount if an asset’s carrying amount is greater than its estimated recoverable amount.
• Depreciation: assets are depreciated at rates based upon their expected economic life using the straight-line method. Leasehold improvements are amortised over the period of the relevant lease or estimated useful life, whichever is the shorter. Land is not depreciated. The following estimated useful lives are used in the calculation of depreciation:
  • Buildings: 10-50 years
  • Electrical & mechanical equipment: 5-60 years
  • Civil works: 30-75 years
  • Mobile plant: 3-20 years
  • Control systems: 5-8 years