The aim of this study is to investigate dispersion and deposition characteristics of different particle diameters (0.5-5-10 mu m) for a displacement ventilated and floor heated environment, experimentally and numerically. The experiments are performed in a reduced scale model with the operating parameters determined regarding to the similarity. Results are used to validate simulation outputs obtained via Eulerian-Lagrangian method. Three different outlet opening configurations and particle source heights are considered. Results are compared in terms of air change efficiency (ACE), average concentration of the room and the breathing height, contaminant removal effectiveness (CRE) and deposition fraction. It is disclosed that contaminant distribution is highly related with the outlet opening configuration and particle source position. Moreover, it is figured out that for the best ventilation strategy with the operating parameters to be determined, related performance indices and area of concern to be protected from particles must be well defined.