A convection transport visualization technique is suggested to analyze the indoor air environment (IAE). A two-dimensional and laminar displacement ventilated room with discrete heat and contaminant sources is numerically investigated. Based on the governing equations, three convection transport functions, i.e. streamfunction, heatfunction, and massfunction, are derived to describe the fluid, heat, and contaminant transport processes, respectively. Main attentions are focused on the effects of the strength of heat source (Gr), the strength of contaminant source (Br), the strength of external ventilation (Re), and the positions of inlet/outlet openings on IAE. Numerical results illustrated that the abstract transport behaviors of the fluid, heat, and contaminant indoors are clearly exhibited by the convection transport functions which provides a simple but practical means of assessing IAE.