The purpose of this study is to propose a residential building model with voids which is appropriate for hot and humid regions of Asia with high population densities that also reduces the environmental load of buildings. This paper will explain an outline of a porous-type residential building model in Hanoi and the design process for introducing voids in buildings in order to improve natural cross ventilation effectively. Furthermore, the effects of natural ventilation, solar shading, and some devices for air conditioning systems for reduction the cooling and environmental load are estimated. (C) 2004 Elsevier B.V. All rights reserved.