Numerical study: How does a high-rise building affect the surrounding thermal environment by its shading?

In rural Japanese cities, many old and densely populated urban districts have been replaced by highrise residential buildings because of urban redevelopment. High-rise building affects the sunshine conditions and wind environment of the surrounding areas. These problems have been already discussed; however, it is rarely discussed how high-rise buildings affect the outdoor and indoor thermal environment of their surroundings. Particularly, shading is a serious problem in winter because it makes the outdoor environment colder and increases the energy consumption for heating of adjacent buildings in addition to daylight shortages. The shading effect of a high-rise building on the outdoor and indoor thermal environment in winter is simulated by a 3D CAD-based thermal environment simulator. As a result of the simulation, shading effect by high-rise building at noon extends widely to the area apporoximately 200m away in the north, but the 7 °C difference in the mean radiant temperature in the shaded area is caused by the surrounding space geometry and material. Also, in the northern or western street of high-rise building, many shops exist and their facade with large windows make the shading effect on the building heat load more remarkable. The building heat loads of these buildings are more than 30% larger than that in the case when the high-rise part is removed.