This study aimed to investigate the dimensioning cooling power demand in the current and future climate in office buildings, using the new cooling design days for Finland, which have been chosen using SFS-EN ISO 15927-2 standard. Therefore, two cooling systems, the all-air, and the air-water are compared in size and performance for the new design days with a 1% risk level in the current climate and future scenarios. The dimensioning of radiant cooling panels for the air-water system and the airflow rates for the all-air system are conducted. Moreover, the dimensioning cooling power demands are compared to the peak cooling power demand for the whole summer using TRY 2012. The results showed that depending on future climate scenarios, the dimensioning cooling power demand will increase by about 5-13% and 7-17% with the air-water and all-air systems, respectively.