Total project cost is the structured sum of all cost, needed for the project execution.
Total project cost comprise also customer’s reserve (a part of the management reserve) and the cost for the project preparation and project management. Customer’s reserve serves for his later additions to the work contract.
Cost are not expenses! It is not only accounting difference, but also difference in time. For example it is possible to purchase material and pay for it before it is consumed. Expenses originate by paying, cost originate by consuming the purchased material.