Natural ventilation in building is a common way to ensure indoor air quality, thermal comfort in summer and reduce energy consumption due to air conditioning. However, efficiency of such a system is highly dependent on climatic conditions. In this paper we review the different ways to use natural ventilation in buildings and then we propose indicators to assess the potential of a site. The study focuses on the Mediterranean climate and especially the coastal zones, characterized by the occurrence of thermal breezes which can be used to improve natural cross ventilation.