Maintenance of the PFI asset is the responsibility of the private sector contractor, to deliver the required contract services and to meet agreed end of project life asset hand back conditions. The cost of hard facilities management and lifecycle maintenance requirements is a risk that is transferred to the contractor, underpinning a principle of optimising whole life asset design and maintenance efficiency. In some cases the contractor passes lifecycle risk through to a sub contractor of hard facilities management services, and in other cases this risk is retained by the project company and its investors, and may be mitigated through the use of lifecycle cash reserves.