The purpose of this paper is to investigate a load calculation method for underfloor air distribution(UFAD) and its energy saving potentials. For the load estimation in UFAD, heat gain factors which are human, equipment and lighting need to be identified. The design total heat gain for the first case, effective heat gain factor(EHGF) for the second case, and 65% of the total heat gain were applied. Other cases ara applied differently in lighting load. Energy simulation result show that the saves energy by 6% when compared to the first case.