Occupants’ behaviour and strategies to encourage behavioural changes need to be addressed in workplaces to reduce energy consumption. In this study, the Theory of Planned Behaviour (TPB) was integrated for the first time with an office virtual environment (VE) to investigate the adequacy of the VE in the comfort and behaviour domain, while understanding its effect in predicting individuals’ energy-related intention of interaction with the building systems. 104 One hundred four participants, randomly divided into two groups, were recruited to answer questionnaires (TPB, comfort, interactions, sense of presence and cybersickness). Two test sessions were conducted at a constant indoor air temperature: an in-situ experiment was compared with the virtual counterpart. Findings revealed an excellent level of presence and immersivity and the absence of high disorder levels. A good agreement between the two environments was highlighted in terms of thermal comfort, number, and type of interactions (one interaction focused on window opening for 71-81% of subjects). Moreover, no differences were discovered between the results of a multiple regression model in both real and virtual environments. In particular, the analysis identified the knowledge of energy consumption as the main predictor of behaviour because it accounted for about 12% of the variation in the intention of interaction in both tested environments. Thus, the suitability of the virtual environment could offer an effective tool for decision-makers and researchers to develop strategies aimed to design more comfortable and less energy-consuming buildings.