Target Air Change Rate and Natural Ventilation Potential Maps for Assisting with Natural Ventilation Design During Early Design Stage in China

• Main Authors: Liwei Wen, Kyosuke Hiyama
• Format: Article
• Language: English
• Published: MDPI AG 2018-05-01
• Series: Sustainability
• Subjects: natural ventilation; design strategies; air change rate; cooling effect potential; climate analysis
• Online Access: http://www.mdpi.com/2071-1050/10/5/1448

To achieve the desired free-cooling effect, the preliminary design of natural ventilation should be combined with discussions of building shape during the early design stages. In an earlier study a method for supporting strategic design of natural ventilation was developed that relied on the target air change rate and natural ventilation potential. The authors defined target air change rate as a point where the gradient of the increase in the cooling effect from natural ventilation reached a maximum. To verify the viability of the proposed method, the robustness of the target air change rate is examined in this paper using a typical Chinese office building model with representative operation conditions in five climate zones of China. The impacts of insulation level, thermal capacity, and window-to-wall ratio (WWR) on the target air change rate are investigated. In addition, the target air change rate and natural ventilation potential maps in China are created to inform rough natural ventilation strategies in the early design stages. According to the evaluation results, simple natural ventilation strategies are sufficient for buildings with relatively low internal gains to realize the required small target air change rate, regardless of climate conditions. Under moderate internal gains condition, well-organized and examined natural ventilation strategies are required in the Hot Summer and Warm Winter zone and the Temperate zone. However, these strategies are particularly suggested for cities in the Temperate zone with a warm climate due to the higher cooling potential. Moreover, elaborate natural ventilation design is recommended for buildings in cold climates when the internal gains are increased to a high level.