Deep Energy renovation (DER) adopts a whole building approach and achieves much larger energy savings than shallow energy renovations that typically only included a small number (one or two) of upgrade measures. DER includes the installation of high levels of insulation, uses renewable energy technologies and minimises uncontrolled air leakage by achieving air permeability levels no greater than 5 m3/h.m2 to achieve building energy ratings (BER) of at least A3. It can also include the installation of mechanical ventilation in order to ensure an adequate level of controlled ventilation for the occupants. The impact of energy efficient measures such as DER on indoor air quality (IAQ) is largely understudied internationally. Although research shows that improving the energy performance of a building improves indoor temperature and occupant comfort, the impact on IAQ is unclear. In this research project the air concentration of pollutants, PM2.5, formaldehyde, carbon monoxide, carbon dioxide, BTEX along with temperature and relative humidity will be measured in a sample of homes participating in the Sustainable Energy Authority of Irelands Pilot DER programme. Post DER surveys will also include an assessment of the performance of the ventilation installed as part of the DER. Preliminary results from a sample of 8 homes post DER are presented here.