This study evaluates the effects of the position, thickness and application of PCMs on different building components on a building's energy consumption. In this study, in a three-storey building with a 10 m/30 m sized in Diyarbakir in the hot-dry climatic regionwas used. In order to reduce the total, cooling, and heating energy loads, different alternatives were created by applying the PCM in the building envelope and inner surfaces of the studied unit. The energy performance was evaluated with the simulation tool EnergyPlus (9.0.1) for every different alternative, operative temperature of the unit for 21st January and 21st July was also calculated. Total energy load of the building was reduced when 5 cm PCM was applied on position 2 on the building envelope. When PCM was applied on inner walls and floors in addition to the building envelope (App4) total energy load of both units and the building was reduced (9.69%). However, in none of the alternatives energy consumptions in the units were equal; only the difference between them could be reduced. With the positive effect of App4 on the operative temperature, U2 was replaced by U5 as the unit with the lowest energy consumption on January 21. (C) 2020 Elsevier Ltd. All rights reserved.