In spite of its importance, the analysis of airflows has significantly lagged behind the modeling of other building features because of limited data, computational difficulties, and incompatible methods for analyzing different flows. Methods have been developed to analyze airflows in HVAC ducts and to estimate infiltration, but the interaction between building HVAC systems and infiltration airflows has seldom been studied. This paper emphasizes the numerical aspects of an airflow network method that would provide a unified approabh to building airflow calculations. It also discusses the limitations of the method and poorly understood factors ,that could profit from further research.