The height of residential indoor space should not be less than 2.40 meters, and the distance between buildings should not be less than the coefficient of building height multiplied by 0.70. If it is less than this distance, it will affect indoor lighting, ventilation and residents' life. According to the national regulations (design code), the sunshine time from winter solstice is not less than 1 hour (bottom window of residence). The distance is the height from the outdoor terrace of the building to the eaves of the building, and it is the solar altitude angle at noon from winter to Sunday. It can also be calculated by the ratio of building height to building spacing = 1: 1.2.