In recent years skyscrapers have been increasing in urban centers. Skyscrapers consume more energy than regular buildings do. In fact, they take up approximately 40% of total energy consumption, and the carbon emissions from these buildings account for 21% of total emissions. In order to reduce energy consumption by buildings, renewable energy options are being looked at for application to buildings. In particular, windpower has many advantages since it can be operated constantly except for periods when there is no wind, and the wind generated by having high rise buildings close by or by having the generator placed on the rooftop can improve efficiency. A Building Integrated Wind Power (BIWP) is being attempted in various ways as one way to use wind power in buildings. The airflow in urban areas depend on a complex of factors including the form, size and location of nearby buildings, or the angle or velocity at which the wind blows. To apply BIWP, studies are needed on the optimal airflow conditions caused by nearby buildings. This study analyzed the characteristics of air flow near the rooftop of buildings in order to apply wind power generators. Mid-rise buildings scattered across the city were used for the analysis. To identify the effects of the air flow caused by nearby buildings, a cluster of buildings formed by 2 mid-rise buildings of same size and another cluster of 4 mid-rise buildings were analyzed. A wind tunnel experiment was conducted to review the distribution of wind speed and turbulent flow near rooftops of mid-rise buildings. Based on such data a comparison with the CFD interpretation was carried out to conduct a validity test for CFD interpretation. Moreover, to review the overall air current flow and characteristics near buildings. a CFD interpretation was conducted. The following findings were acquired.
The maximum values of the wind speed ratios are shown in Case 1, 2 at the center of the upper part of the roof, and Case 3 at the side. All of the cases showed a measurement height of 105m. Case 1 showed 20% increase in reference wind speed, Case 2 increased 19% and Case 3 increased 8%.
The increase in wind velocity due to the Venturi effect can be increased by taking advantage of the fact that the wind power generator’s output is in proportion to the wind speed taken to the third power. In addition, the correlation between the CFD analysis and wind tunnel data was high at approximately 0.9 or higher, indicating that CFD interpretation can be applied to air current analysis near rooftop floors for the development of wind power generators for buildings.