Coupling thermal simulation and airflow calculation for a better evaluation of natural ventilation strategies

A lot of building simulation tools are available today on the market. Most of them rely on
very simplified hypotheses concerning the appraisal of airflows: very often, a constant (userdefined) airflow is supposed, either to quantify the infiltration rate of a building or to estimate the coupling coefficients between zones. On the other hand, some recent tools become
available to calculate air flow couplings between the different zones of a building or between
a building and its environment. Those tools rely on simplified hypotheses concerning the
temperatures distribution in a building.
From that observation, it is obvious that a strong complementarity exists between both
categories of tools. Several methods are available to perform this coupling and they are
briefly described in the paper. Then, one of these methods is considered in details and
successly engineered for the global simulation of two Case Studies of the IEA Annex 30
project: an office building in Germany and an appartment building in Poland. Both
applications show the relevancy of the coupling process and the impressive impact on some
simulation results. A parametric analysis of some key variables is also performed.
As a conclusion, the paper identifies the limitations of the coupling method which is used in
this case and proposes some improvements based upon an increase of the automization and
integration process.