Depreciation should be according to the normal accounting principals of the organisation. If depreciation is 20% per annum, the charge will be 20% per annum (probably on a daily or monthly basis) from the date of purchase or use in the project, whichever is the later. If the normal depreciation rate for the organisation is 50% per annum then that will be the cost on a daily or monthly basis. If 100% depreciation is the norm within the organisation, then 100% depreciation will be charged on the date of acquisition/use within the project.