Modelling natural ventilation for summer thermal comfort in Mediterranean dwellings

There is an urgent need for adequate natural ventilation in apartment dwellers in densely built regions that could improve occupants’ summer thermal comfort and reduce the rapidly increasing energy demand for cooling. The aim of the research reported here was to identify natural ventilation strategies that could offer energy efficient refurbishment solutions for domestic buildings whilst maintaining thermal comfort of occupants. An urban multi-storey apartment building in the city of Athens was selected for this study, which is representative of over four-million Greek domestic buildings. Four retrofit strategies were tested with the aim of offering indoor air temperature reductions and increased ventilation rates relative to the existing single-sided ventilation strategy of the building, using computational fluid dynamics (CFD) simulations. The ventilation performance of all strategies varied with wind speed and direction due to the proposed design configurations. During buoyancy driven flows, acceptable ventilation rates for comfort could be achieved with the implementation of a wind-catcher and a dynamic façade. Under wind-driven ventilation, these strategies delivered significant increases in ventilation rate (up to 7 times) and contributed to reductions in indoor air temperatures of up to 2oC, relative to the existing ventilation strategy. Cooling by water evaporation enhanced the cooling performance of the wind-catcher providing up to 4oC temperature reductions. The successful performance of the proposed strategies highlights the potential significance of reducing energy consumption and improving thermal comfort.