On the effects of decoupling airflow and heat balance in building simulation models.

Abstract

Several thermal building simulators also allow coupled modelling of bulk air movements using airflow network models. However, solving the combined flow and thermal problem can be problematic, both in the context of traditional building simulators and for modern environments, where both airflow and thermal models are formulated as sets of differential-algebraic equations (DAE). For variable-time-step DAE-based simulators, difficult coupled problems often lead to small time steps and slow simulations. In this paper, the author investigates the differences between full where all equations are solved simultaneously, and so-called ping-pong coupling, where airflows from the previous time step are used.