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International audience; The current challenge is to reduce the building energy consumption, in hot and humid climates, for which air conditioning is widespread. Up to now, the lack of criteria that identify the available cooling resources and the level of performance of technical solution has represented the major obstacle. To address these issues, the authors propose a new set of indicators to fully inform the decision-making process of the bioclimatic design of fully space-conditioned buildings in a hot and humid climate. This set of indicators provides an overview of the exploitable environmental resource (external air through external convection, natural ventilation and sky radiation cooling) referred as the Environmental Resource Indicators and of the capacity of the building to exploit those resources referred as the Building Performance Indicators. The indicators are implemented for a very basic two-story residential building in the hot, humid climate of Djibouti. The case study shows not only the ability of the indicators to reflect the bioclimatic performances of the buildings but also their ability to give an overview of the building heat exchanges, from which the implication of improper bioclimatic solutions on building cooling consumptions can easily be identified. These indicators are a means to help choose which technical solutions are most suited to the local climate, which is very useful for designers and architects in the early stages of building design.

International audience; In the Sub-Saharan African countries like Djibouti, the energy situation, the high rate of urban areas growth and the inadequate techniques of construction offer an exciting potential for the bioclimatic approach and sustainable construction. However, this poorly explored potential requires an investigation of different construction types in Djibouti and a good knowledge of the behavior of buildings components. Further a low energy building can be obtained because of the good realization of all its components. In fact, roofs call for attention as they represent a large part of a building's total surface area and amount of absorbed solar radiation. The goal of this paper is to investigate the benefit of using double skin-ventilated roofs for reducing cooling load under the Djiboutian climate. It is a first step towards ideas that will transform local construction practices to make them effective in energy, economic and functional dimensions. During investigation, we compared a ventilated roof assembly with traditional configuration after that the consistency of our model was validated with experiment of the literature findings. The computational fluid dynamics (CFD) model has been used for the characterization of the airflow and heat transfer phenomena in the ventilation cavity and provide fundamental information about the thermal performance of the roof. The results show the amount of the energy saving obtainable by the double-skin ventilated roof.