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Abstract
The research aimed to evaluate the efficiency of applying the natural ventilation passive techniques within a residential space on the indoor ventilation rates and thermal comfort within local hot summer climate. The research revealed that the techniques that depend on thermal buoyancy effect, as a working principle, could achieve significant high ventilation rates within local hot summer climate of high temperatures and solar radiation.
Double wall technique, with variables of air gap, construction material, technique opening dimensions, and position, was investigated using EnergyPlus as a CFD simulation engine to study system efficiency on flow rate and thermal comfort using only passive convective strategy. Investigation was conducted within both day and night conditions and all orientations of solar exposure (east, south, and west orientations). This simulation included testing other passive techniques already existing as a reference case to define natural ventilation passive techniques that are suitable and appropriate to be applied into the local climate of Cairo.
CFD simulations showed that applying double wall technique with the given configurations enhanced ventilation rates at all orientations by mean values that vary from 68.9% to 85.9%, with maximum recorded mean air velocity of 0.3 m/s. In case of high quality of outdoor supply air, these high ventilation rates improve the indoor air quality levels.
The results also revealed that applying technique within eastern façade can enhance thermal comfort levels inside a space by a maximum mean operative temperature value of 3.65°C at night, which met thermal comfort acceptability limits.
Within southern and western orientations, applying system did not enhance the thermal comfort levels at day or night conditions. A supplementary study revealed that reducing incoming air temperature while applying double wall technique can reduce the indoor mean operative temperature by around 0.3°C to 0.4°C for each reduction in incoming air temperature of 1.0°C. This gives promising indicators that applying double