Integration of three-dimensional CFD results into energy simulations utilizing an Advection–Diffusion Response Factor

Indoor climates have a three-dimensional spatial distribution caused by three-dimensional airflow. To understand the building performance, we must integrate these spatial distributions into building simulations. However, conventional energy simulations are based on the assumptions that perfect mixing of air streams with different temperatures occurs. Therefore, it has been difficult to evaluate the effectiveness of energy conservation methods that utilize a thermal distribution mechanism within a room. Taking into account the above conditions, we have developed a calculation method that can achieve more accurate time-series analysis. This is accomplished by combining the newly developed method with the conventional energy simulation method. In the new method, we calculate, in advance, the heat response in a static flow field using computational fluid dynamics (CFD) analysis. Then we calculate Advection–Diffusion Response Factors and integrate them into the energy simulation as a factor in the three-dimensional thermal distribution within a room. In this paper, we show a calculation example using the model for high ceilings with high-temperature exhaust. As a result, we conclude that our new calculation method, in combination with a dynamic heat load calculation, will offer possibilities for a long-term, non-steady-state energy simulation, even on personal computers, based on the room temperature distribution data obtained using steady-state calculations with CFD analysis.

• Indoor climates have a three-dimensional spatial distribution caused by airflow.
• However, consecutive CFD analysis is extremely costly in terms of time.
• Then a method to integrate spatial distributions calculated by CFD analysis was developed.
• The response factors calculated by CFD analysis under steady boundary conditions are employed.
• In a case study, it took only one tenth hour compared to CFD analysis alone.