Since buildings are responsible for 25% of greenhouse gas emissions globally, energy efficiency renovations (EERs) are key to reduce energy use and greenhouse gas emissions. Therefore, it is necessary to understand the determinants of performing an EER. An extended model of Ajzen's Theory of Planned Behaviour was implemented to examine the impact of subjective norms, perceived behavioural control and attitudes on the intent to perform an EER. Our study additionally incorporated predictors such as household income, renovation knowledge, bill consciousness, certainty of profitability, and environmental concern. Our results are based on a sample of 804 Flemish persons (Mage = 53.99; SDage = 14.28; nwomen = 375 (46.64%)) and we used structural equation modelling for analysis. Results indicated that subjective norms, perceived behavioural control and attitudes significantly predicting intention, with attitude being more than twice as influential as subjective norms. Income was associated with both renovation knowledge and perceived behavioural control. Furthermore, a positive attitude towards EERs was linked to certainty of profitability and environmental concern. Our results suggests that communication should emphasize financial benefits and environmental impact to effectively change attitudes, while renovation knowledge has a role to play in increasing peoples' perceived behavioural control over performing an EER.