Abstract
Mechanical ventilation consumes a huge amount of global energy. Natural ventilation is a crucial solution for reducing energy consumption and enhancing the capacity of atmospheric self-purification. This paper evaluates the impacts of indoor-outdoor temperature differences on building ventilation and indoor-outdoor air pollutant dispersion in urban areas. The Computational Fluid Dynamics (CFD) method is employed to simulate the flow fields in the street canyon and indoor environment. Ventilation conditions of single-side ventilation mode and cross-ventilation mode are investigated. Air change rate, normalized concentration of traffic-related air pollutant (CO), intake fraction and exposure concentration are calculated to for ventilation efficiency investigation and exposure assessment. The results show that cross ventilation increases the air change rate for residential buildings under isothermal conditions. With the indoor-outdoor temperature difference, heating could increase the air change rate of the single-side ventilation mode but restrain the capability of the cross-ventilation mode in part of the floors. Heavier polluted areas appear in the upstream areas of single-side ventilation modes, and the pollutant can diffuse to middle-upper floors in cross-ventilation modes. Cross ventilation mitigates the environmental health stress for the indoor environment when indoor-outdoor temperature difference exits and the personal intake fraction is decreased by about 66% compared to the single-side ventilation. Moreover, the existence of indoor-outdoor temperature differences can clearly decrease the risk of indoor personal exposure under both two natural ventilation modes. The study numerically investigates the building ventilation and pollutant dispersion in the urban community with natural ventilation. The method and the results are helpful references for optimizing the building ventilation plan and improving indoor air quality.
Highlights
In certain cases [single-sided, 0] with an idealized isothermal condition (Figure 3a), the main vortex locates in the centre of the canyon, and the air mass is transported by mechanically driven flow from the top layer to the bottom of the canyon
This work sets up a useful method to investigate the impacts of different building ventilation schemes and the indoor-out door air temperature differences on the flow field and the traffic-related pollutant dispersion
The application of the Computational Fluid Dynamics (CFD) modelling is extended to the area of exposure and connected to public health, which is a novel approach
Summary
More than half of the current global population lives in urban areas. This proportion keeps increasing and could reach 68% by 2050 [1]. Rapid urbanization, deteriorating air quality, and air pollutants exposure increase the risks of respiratory and cardiovascular diseases on residents in urban areas [2,3]. Indoor activities occupy about 90% of the majority of people’s lifetimes, and indoor air quality is affected by outdoor air pollutants via ventilation. The residents living in curb-side buildings are exposed to higher concentrated air pollutants from traffic emissions [3,9,10], and have a pressing need of optimizing ventilation plans to reduce exposure risks [11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
