This paper investigates the overall thermal performance of vernacular buildings in Nicosia, Cyprus and highlights the role of semi-open spaces in improving the thermal comfort of the aforementioned structures. The novelty of the study lies in the fact that it presents, in a comparative way, field measurements carried out in five traditional buildings, discussing at the same time the impact of authentic architectural features, as well as of contemporary interventions, on the bioclimatic function of the original building envelope, taking into account the daily use of the premises under investigation. The research outcomes highlight the positive contribution of semi-open spaces to the thermal comfort of vernacular buildings, especially during the cooling period (summer). Contemporary architectural interventions, such as the conversion of semi-open spaces into closed indoor spaces, as well as the behaviour of occupants, are also found to affect the thermal performance of the traditional building envelope.