An abbreviation for net present value, representing the cost of a process or product calculated in the present day currency. The premise is that the investment of money today can earn interest and so has a greater present value than money received at some point in (p. 258) the future. The NPV is therefore determined from the sum of the present values of each individual cash flow starting with the start of the process or product. The annual discounted cash flow is obtained for each year’s rate of interest. The greater the NPV, the more economically attractive the process. A negative NPV indicates an economically unviable process. The NPV is dependent on the choice of interest rate used in the calculation.