NEW EXPERIMENTAL BUILDING FOR NATURALLY VENTILATED SOLUTIONS IN THE SUBTROPICAL REGION

Summary How to reduce the energy consumption and also have better living environment is the critical issue of ventilation solutions in the sustainable building view. Taiwan is located in subtropical region, and the situation is very typical hot and humid living environment. The design strategies for the sustainable buildings were not only aimed to lower the temperature and reduce the moisture in summer, but also the ventilated strategies ought to be in connection with the different weather conditions. It is great beneficial on utilizing the natural ventilation, driven by the natural forces such as wind-power and gravity (stack effect), to save the energy consumption of air conditioning and to maintain healthy indoor-environment. This study tried to conduct the solutions of natural ventilation strategy in the new experimental building, which was built for the research of sustainable living in Taiwan. Four different types of natural ventilation systems were taken to be installed in eight rooms with the same characteristics, including room volume, openings, shapes, furniture and bathroom. The wind tower with stack effect, large openings with proper porous screen, elevated floor with thin and thick local marbles and the opening shutters to control wind direction were the ventilation variables in the experimental building. Room temperature, relative humidity, indoor wind velocity and IAQ factors were all measured for at least one week to monitor long term data and adjust the variations of microclimate influences. The CFD (Computational Fluid Dynamics) techniques were also used to be the visualization of numerical calculations, and compared with the measured results. The questionnaire and living diary were all taken down after the daily living to analyze the psychological and physiological perspectives. Results show the better natural ventilated situations firstly depended on the all year round wind direction, outdoor air quality and the building design. There should be different solutions in summertime and wintertime, which were more flexible and controllable to adjust comprehensive situations. Furthermore, thermal comfort was the second concerned issue decided the ventilation rate and ventilation efficiency in different season. In comparison with ISO 7730 and ASHRAE standard 55-2004, people usual live in high temperature and humidity level appear to stand higher thermal level than people live in frigid region. Therefore, the natural ventilation system should follow up the thermal comfort to decide, and to be carefully control in health aspects for IAQ issues. According to one year monitoring, conclusions can be conducted as the whole flooring displacement ventilation system with the mass cooling effect is the most suitable and effective ventilation strategy. The transom openings are also needed to be the air outlet, which can be opened in different season.