In this paper, the thermal performance of the doctors and nurses housing building in Aleppo walls, consisting of the hollow blocks with inside styropor sheet and compare it with a wall consisting of hollow blocks with eternal continuous insulating styropor layer and the effect of adding continuous insulating layer on the existing walls. The study showed that the use of the block with inside styropor slice was not useful regarding the thermal behavior and causing large and intense thermal bridges generation. However the use of block with continuous styropor layer made the temperature distribution more uniform and reduced the energy flux by 36.7-70%.