The scope of this work was to investigate the summer ventilation performance of three high thermal inertia solar thermosyphonic configurations, used as night natural ventilation systems. The aim was to assess the effectiveness of each configuration and orientation on night natural ventilation. Three designs, (a) SC1 a conventional SC, (b) SC2 a thermal chimney with duct attached behind the absorber, and (c) SC3 a thermal chimney rectangular duct with two surfaces glazed. Thermal performance of each SC was investigated by simulations in EnergyPlus followed by a Sensitivity Analysis performed on predicted results. For calibration and validation, output variables were checked and verified for coherence against published experimental data of similar nature found in literature. Analysis disclosed SC2 facing West the most effective design. Simulation results showed that a concrete thermal chimney 3 m tall with 0.1 m wall thickness and 0.2 m air gap exhibited night cooling capacity, depending on configuration and orientation, was found ranging from 3.27 MJ/m-day for the SC1 faced South, up to 10.0 MJ/m-day and 14.7 MJ/m-day for the SC3 and SC2 facing West, respectively. SC2 faced West was predicted to deliver flow rate 98% higher than the flow rate of a same size conventional SC1 faced South. (c) 2012 Elsevier B.V. All rights reserved.