This paper presents a novel bottom up approach to modelling the energy savings potential of energy efficiency improvement measures to be applied through retrofit of the existing dwelling stock. It takes advantage of a newly available, rich dataset on the construction characteristics of the 2011 housing stock in Ireland. The methodological innovation centres on the use of wall construction type in the modelling and analysis. While Ireland is the focus, this approach is applicable to any EU member state for which data on dwelling characteristics exists from surveys carried as part of Energy Performance Certificate calculations. The model is calibrated to the national energy balance for 2011 by varying the internal temperature assumptions. Sensitivity analysis is performed on the effects of internal temperature and rebound. The paper also highlights some limitations posed by data availability on the accuracy and sophistication of models that can currently be developed, specifically in the Irish case. (C) 2015 Elsevier Ltd. All rights reserved.