A study is described, in which existing literature-based data is collected and analysed, and then used as the basis for a complementary computational study of the implications for ventilation and for radon concentrations of a number of energy efficient retrofit scenarios, relevant to the Irish building stock. The study will supply information surrounding the better implementation of radon legislation, and provide information on full integration of environmental requirements and considerations into other policies. This paper describes the incorporation of radon as the pollutant of interest into an existing modelling framework, IAPPEM, and demonstrating the application in predicting radon concentrations in the indoor environment. The adapted model, which describes airflow in the context of pressure differentials, will be used to carry out simulations that address issues raised within the Irish National Radon Control Strategy, specifically (i) pre- and post- radon concentrations in buildings that have undergone an external insulation energy retrofit, and (ii) pre-and post-retrofit data for buildings with initial radon levels in excess of 200 Bq m-3The preliminary results presented in this paper suggest that increasing a building’s airtightness increases indoor radon concentrations in certain situations, and can result in radon concentrations exceeding the recommended reference levels of 200 Bq m-3.