Effect of thermal inertia and natural ventilation on user comfort in courtyards under warm summer conditions

Abstract

Thermal inertia and natural ventilation are strategies widely used and studied in indoor building performance. However, little analysis has been done on its effect on the outdoor microclimate. Furthermore, this analysis is needed for the specific case of inner courtyards, given that these outdoor spaces are highly affected by their surrounding building surfaces. This study takes a real-scale prototype constructed for the 2019 Solar Decathlon competition in Hungary as a case study to analyze the thermal inertia and ventilation effects on the thermal performance of courtyards. Monitoring data are used to calibrate a simulation model that combines BES and CFD to predict the thermal performance for three wall configurations with different inertia and two situations: the closed courtyard and the ventilated courtyard. Results show that the thermal inertia and ventilation effects inside the courtyard are similar to what is generally observed inside the buildings. Thermal inertia for the close courtyard was able to increase the courtyard tempering effect up to 1.6 °C and comfort up to 1.4 °C UTCI. The ventilation reduced the tempering potential of the courtyard during the day, but it also reduced overheating during the night. Depending on the wind speed it can also increase thermal comfort.