Determining optimum configurations of solar collecting window systems for double skin envelope

This study investigates the influence of cavity depth and the conditions of louvers on indoor thermal environments to propose optimum configurations of solar collecting window systems that can be effectively applied to double skin envelopes. Field measurements were performed for a reduced-scale mock-up model to represent the analysis results for a full-scale model. Computer simulations were performed using computational fluid dynamics (CFD) under a variety of cavity and horizontal louver conditions to validate the results from the field measurements. Two theoretical computation models, namely the k-e RNG and k-e standard models, were applied to the simulations. The results of field measurements imply that a cavity depth of 0.2 m was most effective in supplying air from a cavity to an indoor space with the required velocity and temperature. The validated computer simulation results imply that the k-e RNG model was more effective than the k-e standard model in predicting the properties of airflow in cavities where turbulent patterns occur due to the buoyancy effect. According to the analysis based on the k-e RNG model, a cavity depth of 0.2 m appeared to be optimum to achieve the required ventilation rates with energy savings. The temperature and velocity of air supplied from the cavity to the indoor space was most effective when the tilt angle of the horizontal louver was 45°. While airflow passed through the cavity exchanging heat with the louvers, it was not significantly blocked by the tilted louvers. This improved natural convection and ventilation rates in the cavity. This study suggests that the solar collecting window system could be effectively applied to building envelopes in winter.