Comfort criteria in building are increasing continuously. Multiple studies tend to use CFD approaches in order to predict and optimize the flow conditions accurately. One of the most relevant problematic is the extraction of the CO2 by kitchen hoods. In the present work, a new solver, based on a buoyancy Boussinesq solver and a turbulent passive scalar transport equation, is developed in OpenFoam to model the heated CO2 extraction by a rotating fan using the Multiple reference frame (MRF) approach. The new solver is first validated successfully against experimental results of a heated cavity and CO2 diffusion. An improvement of 30% in the capture efficiency is reached by increasing the extraction flow rate of the fan from 100 to 300 cfm. An extraction efficiency of 100% is observed for flow rates above 330 cfm. The novelty of this study is to present a new open-source solver able to model the rotation of the whole fan, CO2 transport and heat exchange simultaneously in steady state.