Towards a deductive model for studying air movement in underground buildings, with reference to Egypt

In order for mankind to live sustainably, the rate of earth-resource use must be set to a limit that allows healthy replenishment. In accordance with the world´s increasing housing demand, limited land-surface resources, fossil fuel depletion and global warming, natural and built environments require different and creative solutions for sound development. For thousands of years, people have accomplished significant environmental benefits by residing underground structures, in the so-called subterranean architecture. Underground buildings can promote the sustainability of our environment by increasing the natural planted areas, reducing fossil fuel consumption, and rationalizing the buildingoperation energy. This can be achieved by employing the soil as an natural heat reservoir for heating (in winter) and cooling (in summer), based on the fact that underground temperature is lower than the ambient temperature in summer, and higher in winter. Therefore, this type of buildings may contribute positively towards an appropriate development to our environment, particularly in response to the abovementioned problems. However, earth sheltered buildings are generally classified into three main types, namely: the fully submerged (atrium plan), the elevational, and the bermed (penetrational) types. Thermal performance is evidently an influential dimension upon living in such buildings. It depends on several variables, out of which is the air movement. This paper seeks the development of a deductive model to study air movement in underground buildings. After addressing the thermal performance variables in general, the study lays particular emphases upon those related to airflow. Out of these, the research analyses in detail the ones applicable to underground buildings, i.e. building form, orientation, fenestrations, courtyards and wind catchers. Different possibilities for each of those are identified, to form an extended matrix for different possible influences upon air movem- - ent in underground buildings. This matrix will then set the foundation to investigate the suitable settings for optimal airflow in underground buildings in Egypt, using virtual models and environmental analyses software, in a following phase of the ongoing research.