Advanced air distribution is essential for the energy-efficient provision of thermal comfort and indoor air quality. This study proposes a novel advanced air distribution, , graded ventilation. The airflow pattern of graded ventilation is characterized by a bimodal distribution of vertical air velocity and a unimodal distribution of vertical air temperature. Graded ventilation possesses four mechanisms for high energy-efficient provision of thermal comfort and indoor air quality. First, graded ventilation has a high conditioned air supply efficiency into the occupied zone, particularly the head level, for both thermal comfort and indoor air quality, due to the push-down and pull-down forces of the internal airflow recycling. Second, graded ventilation decouples outdoor fresh air and return air, with high outdoor fresh air supply efficiency for indoor air quality. Third, graded ventilation utilizes higher-quality conditioned air for the zone, which is more critical to thermal comfort and indoor air quality. Fourth, graded ventilation only handles the cooling load of the outdoor fresh air without handling the cooling load of the return air. Case studies demonstrate that compared with mixing ventilation, Type-I stratum ventilation, Type-II stratum ventilation, and interactive cascade ventilation, graded ventilation improves energy efficiency by 49.7%–55.4%, 24.8%–29.1%, 16.3%–23.3%, and 8.4%–12.3% respectively for thermal comfort and indoor air quality. Therefore, this study advances air distribution for low-carbon, thermally comfortable, and healthy buildings.

中文翻译：

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分级通风概念及通风性能演示

先进的空气分配对于提供热舒适度和室内空气质量的节能至关重要。这项研究提出了一种新颖的先进空气分配、分级通风。分级通风的气流模式具有垂直风速双峰分布和垂直空气温度单峰分布的特点。分级通风拥有四种机制，可高效节能地提供热舒适度和室内空气质量。首先，由于内部气流循环的下推力和下拉力，分级通风对占用区域（尤其是头部）具有很高的调节空气供应效率，可实现热舒适性和室内空气质量。其次，分级通风将室外新风与回风解耦，室外新风供应效率高，保证室内空气质量。第三，分级通风为区域提供更高质量的空调，这对于热舒适度和室内空气质量更为关键。第四，分级通风只处理室外新风冷负荷，不处理回风冷负荷。案例研究表明，与混合通风、I型分层通风、II型分层通风、互动梯级通风相比，分级通风能效提高49.7%~55.4%、24.8%~29.1%、16.3%~23.3%、热舒适度和室内空气质量分别为 8.4%–12.3%。因此，本研究推进了低碳、热舒适和健康建筑的空气分配。