Potencial de la ventilacion natural nocturna. Variables de diseno. (Potential of the natural ventilation by night. Variables of )

The passive cooling techniques such as night time cross ventilation is potentially an interesting strategy to provide substantial cooling energy savings in warm climates. Night cooling ventilation efficiency is determined by three main factors: the external air flow rate in the room, the flow pattern and the thermal mass distribution. The aims of this paper are the followings: first, we analyse and quantify the effects of the factors mentioned above on night cooling ventilation strategies, and finally, we propose a modification of the existing utilisation factor (EN ISO 13790) for taking into account the low energy cooling techniques. This analysis allows a comprehensive sample of typologies to generate guidelines which can help to evaluate different design solutions. The approach will combine a theoretical analysis to characterize globally the enclosures, getting charge/discharge time onstants, with simulation studies based on computational fluid dynamics software.