The study examined significant summer heat effects on a traditional habitation cluster within a compact fabric of the Medina of Constantine, based on building materials and spatial functional architecture. As climate relates to energy effects, the study raises the importance of possible heat gains in the approach of thermal comfort through building materials without using other energy sources. The study employed both empirical and comparative methods to undertake the research work. The empirical method consisted of taking thermal and metric measurements of the habitation cluster and comparing them with current normative requirements in sustainable architecture. The comparative method consisted of comparing results of performance assessment of studied building materials with results of similar materials. The current study adds to researchers' claims about the importance of the Medina's habitation in the face of climatic aggression at times with its architecture and building materials. Medina’s habitat did not have the technological means to preserve some physical comfort and reduce greenhouse gas emissions, yet its architecture used soft means to accomplish the physical comfort. Additionally, the site's well-chosen materials, which are formed by the natural typology, match well with the site’s climate and provide better resistance to material overflow, not to mention their availability and inexpensive cost.