A method and a system suitable for predicting the costs of implementing cogenerations in small-scaled places of business and ordinary homes. Transmitters (3) located at the respective ones of facilities transmit, by radio, data of electric power consumption amounts of the facilities as measured by electric power meters (1) and data of gas consumption amounts of the facilities as measured by gas meters (2), which are received by a receiver (4). Estimation means (5) uses an estimation program to provide, from the received data, cost estimations of a case when cogenerations are implemented in the facilities. Annual cost estimation means provides, from the estimation results of the estimation means (5), annual cost estimations.