PASSIVE COOLING OF HOUSING BY NATURAL VENTILATION R.Kharchi* and K.Imessad Centre de Développement des Energies Renouvelables, CDER B.P. 62, Route de l’observatoire, Bouzaréah, ALGER. * Corresponding author.tel:0021321901503 E-mail: r.kharchi@cder.dz Abstract The building's form and thermal characteristics largely govern the amount of energy consumed by a building. To avoid major flaws of the design, an architect needs to include the evaluation of the building's energy consumption in the earlier stages of the design process. If energy efficiency is not adequately considered during these stages, higher operating cost will accrue over the life of the building. In recent years, scientists, engineers and architects designed successful innovative buildings that use passive cooling techniques, such as natural ventilation. The house studied is a pilot project undertaken jointly by the Centre for Development of Renewable Energies (CDER) and the National Centre for Studies and Research of integrated building (CNERIB) under the MED-ENEC project (Mediterranean Energy Efficiency in Construction structure). The house subject of study is 65 m² surface area, located in the Algiers region characterized by a Mediterranean climate with relatively mild winters and hot, humid summer. This work is to study the comfort inside the house in the summer without air conditioning, ventilation only is considered. Numerical simulation is made under TRNSYS, the results compared with measured values are conclusive. Keywords: bioclimatic housing, natural ventilation, TRNSYS, energetic efficiency in the building 1 Introduction The effects of global warming and climate changes are of relevant concern for environment and human activities in the Mediterranean area. The average air temperature rise of 2 C represents a critical limit beyond which dangerous climate changes should occur by 2030 [1]. More than 90 million people live in the twenty most populated Mediterranean metropolitan areas; according to the actual trend other 70 million of people are expected to move to leave the countryside towards the urban area by 2025 [2]. The global warming and the urban sprawl causes a number of environmental hazards, the urban heat island (UHI) is one of these. This phenomenon on is defined as the air temperature rise in densely built environments respect to the countryside surroundings. The main cause is the modification of the land surface in the urban area, where the vegetation is replaced by extensively built surfaces (typically paved roads and buildings surfaces), characterised by high solar absorption, high impermeability and favourable thermal properties for energy storage and heat release, as well as several anthropogenic. The UHI was first monitored in London back to the 19th century [3]; many studies were performed during the past decades [4–10], showing the quantitative effects of the phenomenon and the correlation with the previously enounced causes. Daily mean UHI typically ranges between 2 and 5 °C, while UHI intensities (defined as maximum difference between urban and background rural temperatures) up to 12°C were registered under particular conditions. This UHI impacts important issues such as: the