Simulation and experimental study of residential building with north side wind tower assisted by solar chimneys

Natural ventilation combined with passive cooling systems can reduce the cooling energy demand in residential buildings. However, the main difficulty in designing natural ventilation systems driven by buoyancy and wind is the simultaneous estimation of ventilation airflows and indoor temperatures. The purpose of this study was to overcome this difficulty by developing a tool that combines a ventilation model (envelope flow) with a thermal multi-zone model of a bioclimatic dwelling known as La Casa de la Tierra. This building, located in Murcia (Spain), incorporates a central wind tower, four solar chimneys, and construction elements with thermal inertia capacity. The ventilation and the thermal models were completely integrated and solved simultaneously. On-site collected data were used to validate the models. In the validation of the air flow envelope model, maximum and minimum root mean square error values of 10.9 m(3)/h and 7.25 m(3)/h, respectively, were obtained for the simulated and measured flows of the solar chimneys. The maximum value corresponded to chimney 2 where an average air flow rate of 58.2 m(3)/h was registered, while the minimum value corresponded to chimney 3 where an average air flow rate of 30 m(3)/h was measured. Different passive cooling strategies were simulated, combining natural ventilation induced by the wind tower and solar chimneys with passive geothermal and evaporative cooling systems. For these systems, the predicted percentage of dissatisfied people was less than 10%, and electrical energy savings of approximately 42% were achieved. These results contribute to increasing awareness of the role that passive strategies can play in achieving the objectives set by the EU for residential building energy efficiency.

Automated summary

The study aimed to overcome the difficulty of estimating ventilation airflows and indoor temperatures in natural ventilation systems, and successfully developed a tool combining a ventilation model with a thermal multi-zone model of a bioclimatic dwelling. The integration of ventilation and thermal models led to efficient passive cooling strategies that achieved significant energy savings and low dissatisfaction rates among occupants. The results contribute to raising awareness of the potential impact of passive strategies on improving residential building energy efficiency, in line with EU objectives.