For optimizing the balance between intellectual productivity and energy use in office buildings, an
evaluating productivity method, which is objective and quantitative, is needed. It is often used cognitive task
performance to evaluating intellectual productivity. But, using task performance has a problem that the
performance is increase by learning effects. Because of the learning effects, it is difficult to evaluating the indoor
environment. In this study, the authors were proposed a new productivity evaluating index “Concentration time
Raito (CTR)”. CTR was based on intellectual productivity model assuming 3-state transition. Aiming to confirm
that CTR is have no relation with learning effect, the authors conducted a subjective experiment. In this
experiment, cognitive task was given and the performance was measured 6 times in 3 days. As a result, the task
performance was increased by learning effects(p＜.05), but the CTR has no significant difference.