Cultural objects in museum are usually kept in a controlled indoor environment which rery heavily on the air-conditioning systems. This practice is to ensure that a stable climate in museum is maintained to prevent the objects from deterioration. As many of heritage buildings were being converted into museums, heavy changes were made to those building in order to accommodate the systems. This leads to some of the architectural features and defining characters of the buildings being removed or altered. However the characteristics of heritage buildings which were built to response with the climatic conditions may help to contribute a better indoor environment for the collections. Several visual observations made showed that they were designed to deal with climate passively and have architectural features that able to regulate the temperature and relative humidity, thus can be utilized by the museums. This paper hopes to provide answer and examples of how by incorporating passive design in converting heritage buildings to museums not only can preserve the authenticity of the buildings, but also for the benefits of preserving the cultural collections inside.