The CLIMA computer program is a scientific tool for studying, planning and calculating various buildings (thermal systems), where unusual planning or operating conditions are requested to be taken into account. It was organized to calculate for an optionally determined period within the year. In the CLIMA, the dynamic analysis of heat transfer in buildings is conducted according to the adopted mathematical model by using a one-hour time increment. As a starting point for the calculation of non-stationary heat transfer in a building, the "Room Thermal Balance Method" was adopted. It was organized for use according to the working conditions (holidays, and time of starting/stopping of heating/or refrigeration) and weather seasons (months of winter and summer) in Syria. The computer program was provided with the TMY Database, which was generated in a previous stage of this work. Moreover, it was also modified to be adapted for using the suggested mathematical models, which are derived in the previous stage of this work, as an alternative to the using of TMY database. (C) 2010 Elsevier Ltd. All rights reserved.