Co-simulation of building energy simulation and computational fluid dynamics for whole-building heat, air and moisture engineering

Abstract

Building performance simulation (BPS) is widely applied to analyse heat, air and moisture (HAM) related issues in the indoor environment such as energy consumption, thermal comfort, condensation and mould growth. The uncertainty associated with such simulations can be high, and incorrect simulation results can lead to a design with adverse effects on health, comfort and functionality of space. In recent years, the use of BPS tools to predict and analyse the HAM behaviour of the indoor environment has grown significantly. Among these tools, Building Energy Simulation (BES) and Computational Fluid Dynamics (CFD) are recognized as potential tools for assessing HAM behaviour of the indoor environment, such as interaction of the HVAC system with convective heat and mass transfer. These tools have strong capabilities, but also some particular deficiencies in terms of boundary conditions, physical models and resolution in space and time. BES is mainly used to assess the thermal performance of buildings throughout the entire year. It is a powerful tool, but when compared to CFD tools it includes simplified air flow, heat and moisture transfer modelling. Detailed HAM modelling of the building indoor environment is possible with CFD. In CFD, however, the implementation of meteorological boundary conditions, the whole HVAC system modelling etc. are significantly less advanced than in BES. In this thesis, it is hypothesized that if used correctly, the combination of BES and CFD tools will increase the accuracy of HAM simulations of the indoor environment. The thesis first presents approaches for domain integration, relevant physical phenomena, interface variables, and coupling requirements. Then, it introduces a newly developed prototype, which integrates BES and CFD for high resolution HAM simulation of the indoor environment. Next, it describes the verification of the prototype. This is followed by the validation study of the prototype, which shows that the accuracy of the HAM simulation is enhanced. Finally its usage potential is illustrated by discussion of the results of real applications in the building industry.