The utilization of buoyancy-driven natural ventilation in atrium buildings during transitional seasons helps create a healthy and comfortable indoor environment by bringing fresh air indoors. Among other factors, the air flow rate is a key parameter determining the ventilation performance of an atrium. In this study, a grey box modeling method is proposed and a prediction model is built for calculating the buoyancy-driven ventilation rate using three openings. This model developed from Bruce’s neutral height-based formulation and conservation laws is supported with a theoretical structure and determined with 7 independent variables and 4 integrated parameters. The integrated parameters could be estimated from a set of simulated data and in the results, the error of the semi-empirical predictive equation derived from CFD (computational fluid dynamics) simulated data is controlled within 10%, which indicates that a reliable predictive equation could be established with a rather small dataset. This modeling method has been validated with CFD simulated data, and it can be applied extensively to similar buildings for designing an expected ventilation rate. The simplicity of this grey box modeling should save the evaluation time for new cases and help designers to estimate the ventilation performance and choose building optimal opening designs.

Vertical greening is one of the effective measures to improve the microclimate and air quality of high-density urban street canyons, and its impact on the thermal environment is closely related to the street canyon morphology. In this paper, based on the characteristics of high-density urban street canyons in the context of Shenzhen City, 12 sets of cases (two orientations, two aspect ratios, and three height-to-width ratios) were simulated and designed using ENVI-met software to study the effects of vertical greening on the thermal environment of buildings under different street canyon morphologies, and to summarize the impact of vertical greening on the microclimate of different street canyons. The results of the study show that the orientation of the street canyon is the most influential factor in the thermal efficiency of vertical greening under the street canyon geometry with the same amount of greening and that the vertical greening effect of east-west oriented street canyons is generally better than that of north-south oriented street canyons in terms of cooling, humidification, and improvement of thermal comfort at the walking level.

Renewable straw resources have not been widely applied due to the lack of performance assessment. This study selected six representative characteristics of rural farmhouses for field research to understand the current state of rural housing and explore the potential application of straw wall units. The study conducted real measurements of multiple properties of straw wall units. Based on the functions and forms of existing farmhouses, a model of a typical farmhouse was established and its thermal performance was evaluated through simulation. The results show that in regions with hot summers and cold winters, replacing clay bricks with straw wall units can reduce the heat consumption per unit area by 77%, and the energy-saving rate of the farmhouse can reach 53.49%. When exposed to fire, the straw wall unit exhibits delayed collapse and produces no smoke or open flames, effectively reducing the impact of the fire. The straw wall unit can withstand 20 consecutive days and nights of exceptionally heavy rainfall while maintaining a low water absorption rate. The compressive properties of the primary recycled straw wall units meets the requirements for the wall's self-weight. Meanwhile, it complies with the thermal conductivity standards for thermal insulation materials. Therefore, straw wall units can be recycled. The results of the study show that straw is a common material in the countryside, the straw wall units made of straw have good material properties and are suitable for country farmhouses. The study promotes the application of straw resources in rural farmhouses, contributing to the realization of sustainable development of the countryside, and offering new ideas for the construction of beautiful rural areas in China.