economic useful life is the duration of time an asset is expected to be productively employed by us , which may be less than its physical life . assumptions on the following factors , among others , affect the determination of estimated economic useful life : wear and tear , obsolescence , technical standards , contract life , market demand , competitive position , raw material availability , and geographic location . the estimated economic useful life of an asset is monitored to determine its appropriateness , especially in light of changed business circumstances . for example , changes in technology , changes in the estimated future demand for products , or excessive wear and tear may result in a shorter estimated useful life than originally anticipated . in these cases , we would depreciate the remaining net book value over the new estimated remaining life , thereby increasing depreciation expense per year on a prospective basis . likewise , if the estimated useful life is increased , the adjustment to the useful life decreases depreciation expense per year on a prospective basis . we have numerous long-term customer supply contracts , particularly in the gases on-site business within the tonnage gases segment . these contracts principally have initial contract terms of 15 to 20 years . there are also long-term customer supply contracts associated with the tonnage gases business within the electronics and performance materials segment . these contracts principally have initial terms of 10 to 15 years . additionally , we have several customer supply contracts within the equipment and energy segment with contract terms that are primarily five to 10 years . the depreciable lives of assets within this segment can be extended to 20 years for certain redeployable assets . depreciable lives of the production assets related to long-term contracts are matched to the contract lives . extensions to the contract term of supply frequently occur prior to the expiration of the initial term . as contract terms are extended , the depreciable life of the remaining net book value of the production assets is adjusted to match the new contract term , as long as it does not exceed the physical life of the asset . the depreciable lives of production facilities within the merchant gases segment are principally 15 years . customer contracts associated with products produced at these types of facilities typically have a much shorter term . the depreciable lives of production facilities within the electronics and performance materials segment , where there is not an associated long-term supply agreement , range from 10 to 15 years . these depreciable lives have been determined based on historical experience combined with judgment on future assumptions such as technological advances , potential obsolescence , competitors 2019 actions , etc . management monitors its assumptions and may potentially need to adjust depreciable life as circumstances change . a change in the depreciable life by one year for production facilities within the merchant gases and electronics and performance materials segments for which there is not an associated long-term customer supply agreement would impact annual depreciation expense as summarized below : decrease life by 1 year increase life by 1 year .
considering the contract terms of 15 years , what will be the total expense with the depreciation of the merchant gases segment?\\n
impairment of assets plant and equipment plant and equipment held for use is grouped for impairment testing at the lowest level for which there is identifiable cash flows . impairment testing of the asset group occurs whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable . such circumstances would include a significant decrease in the market value of a long-lived asset grouping , a significant adverse change in the manner in which the asset grouping is being used or in its physical condition , a history of operating or cash flow losses associated with the use of the asset grouping , or changes in the expected useful life of the long-lived assets . if such circumstances are determined to exist , an estimate of undiscounted future cash flows produced by that asset group is compared to the carrying value to determine whether impairment exists . if an asset group is determined to be impaired , the loss is measured based on the difference between the asset group 2019s fair value and its carrying value . an estimate of the asset group 2019s fair value is based on the discounted value of its estimated cash flows . assets to be disposed of by sale are reported at the lower of carrying amount or fair value less cost to sell . the assumptions underlying cash flow projections represent management 2019s best estimates at the time of the impairment review . factors that management must estimate include industry and market conditions , sales volume and prices , costs to produce , inflation , etc . changes in key assumptions or actual conditions that differ from estimates could result in an impairment charge . we use reasonable and supportable assumptions when performing .