Natural Ventilation in Building Design: Dynamic Performance Metrics and Interactive Modeling

Abstract

This study proposes a new method to evaluate natural ventilation performance in the early design phase by introducing dynamic performance metrics of natural ventilation and developing an interactive tool that applies the metrics. The tool will help understand how a given design utilizes natural ventilation and which spatial variances could improve the effectiveness of natural ventilation. It also looks into important design aspects, including materials, thermal mass, aperture configurations, occupancy etc. These factors influence whether or not natural ventilation might be effective for the given design. There are four sub-topics: natural ventilation metrics, thermal mass and window controls, validation, and tool implementation. These sub-topics, in this order, structure the thesis. First, it introduces dynamic metrics that gauge the degree of cooling power that is achieved through natural ventilation. The metrics will be first developed under steady-state conditions, and be demonstrated in a feasibility study using an interactive design platform. Second, once metrics for steady-state are established, the effect of thermal mass and window controls are considered. Thermal mass interacts with its environment through time in a dynamic way which must be explored to refine the natural ventilation metrics. Therefore, this part will analyze the temperature change through time, examine the impact of different window operations, and further suggest efficient ventilation routines. Third, the process of calculating the dynamic metrics is validated with experiments. This ensures that the proposed method works as intended. Lastly, an interactive design procedure that utilizes the dynamic performance metrics is demonstrated in the 3D modeling environment. This study contributes to early-staged building design in three ways. First, quick simulation time and interactivity will provide users with rapid feedback on different design possibilities. Second, natural ventilation performance is estimated for a customized building design, albeit with some limitations, as opposed to a general box model. The tool may yield different results for buildings with different sizes, features, and construction conditions. By yielding metrics for a specific design, it will help users to alter the design to enhance performance. Third, the tool helps designers understand that the thermal environment is influenced by important factors including window operation, thermal mass, and internal heat gains. Users will be able to learn the sensitivity of the thermal environment to various construction materials and thermal masses, which is pedagogically important.