Simulation comparison between natural and hybrid ventilation by fans at nighttime for Severe Hot Climate (Aswan, Egypt)

Abstract

The computer simulation measures the effect of ceiling and wall fans in decreasing air temperature during nighttime. The indoor temperature exceeds the thermal comfort through the overheated period in Aswan. A high time lag of envelope in the daytime increases the indoor temperature at nighttime. As a result, the indoor temperature becomes higher than the outdoor temperature at nighttime of the overheated period. The simulation study consists of three models according to ventilation conditions (types). The first model that depends only on cross ventilation is called the natural ventilation model. The second model is the hybrid ventilation that consists of natural ventilation (cross ventilation) and mechanical ventilation (ceiling fan). The third model uses wall (side) fan instead of the ceiling fan. The boundary conditions are placed according to the weather conditions in Aswan in the overheated period (July). Simulation results of hybrid ventilation models decreased the indoor temperature from 2 to 4 °C. The wall (side)-average indoor air velocity in the case of wall fan is 1 m/s-fan is better than the ceiling fan-average indoor air velocity in the case of ceiling fan is 0.86 m/s) according to decreasing indoor temperature (4 °C), and airflow is well distributed inside the room at the sitting level.