PROBLEM TO BE SOLVED: To easily and precisely evaluate the energy saving effect of an overall energy plant even when there is no result data matched in amount demanded when an energy saving means is not applied to an object to be evaluated with respect to the result data when the energy saving means is applied thereto. SOLUTION: An energy cost model is developed by using the result data when an energy saving means is not applied, and stored (S501, S502). Then, energy cost when the energy saving means is not applied is calculated from the energy cost model of a division corresponding to division conditions extracted from result data (S503; YES) to be evaluated when an energy saving means is applied and the result data to be evaluated when the energy saving means is applied (S504 to S507). The energy cost when the energy saving means is applied is calculated from the result data to be evaluated when the energy saving means is applied (S508), and the energy costs when the energy saving means is not applied are compared with the energy costs when the energy saving means is applied, and the energy saving effect is evaluated (S509). COPYRIGHT: (C)2005,JPO&NCIPI
