Sick building syndrome, which has become a major public concern in recent years, is caused in part byvolatile organic compounds (VOCs) emitted by building materials. In order to ensure the safety of ourenvironment, it is necessary to predict indoor VOCs concentrations over a long period of time.Long-term prediction of VOCs concentration requires the consideration of the influence of temperaturechanges, and there is a need for a simple prediction method that can be used for this purpose. Theprediction methods that have been proposed thus far, however, do not meet this requirement.