Study on the Influence of Piloti Ratio on Thermal Comfort of Residential Blocks by Local Thermal Comfort Adaptation Survey and CFD Simulations

To get good outdoor ventilation and create shadow areas, piloti is commonly used in tropical and subtropical climate zones, but there are few studies reveal the comprehensive influence of piloti on wind environment in residential blocks, and furthermore, a coupled simulation method, which offers high precision prediction result, is seldom taken into consideration in piloti research field. This work firstly carried out a questionnaire survey in Guangzhou, China, to study on the local acceptance rate (TSV is lower than 1.5) during different SET* intervals. Secondly, a series of cases were simulated by coupled simulation method, which considering convection, radiation and conduction, offering high precision prediction results. At last, by adopting SET* as standard index, taking both of the questionnaire survey result and ASHRAE standard into consideration, the influence of piloti on residential block's outdoor thermal comfort was analyzed and discussed. The results showed that, due to the strict climate, for those area without shading measurement, only the whole space of 100% piloti ratio case meet the need of SET* limitation level (less than 40 °C), for other cases, part of the space is controlled with this level. For the space shaded by piloti, the area percentage that SET* is in the limitation range (less than 40 °C) of 60% piloti ratio case is about 62%, and for 80% and 100% piloti ratio cases, it is 100%. It is noticed that when piloti ratio is 40%, the thermal comfort of space shaded by piloti is very strict, which should be due to the low wind velocity. A 100 percent piloti ratio can highly improve the outdoor thermal comfort, and 100% area space meet the need of 30% acceptance rate (35°C), and about 40% area meet the need of 65% acceptance rate (34°C).