Research on the Design Parameters of Outdoor Transitional Spaces Based on the Improvement of Thermal Environment

Global warming and urban expansion impose far-reaching, negative implications on the quality of the outdoor thermal environment in residential areas. Due to its potential for microclimate regulation and easy configuration with less site restrictions, the transitional space is an effective mitigation measure to transform existing outdoor spaces for thermal discomfort. The point of this article is to explore the optimum design parameters of the transitional space for increasing outdoor thermal comfort, with a focus on its orientation, aspect ratio (H/W), plan aspect ratio (L/W), and enclosure degree. The ENVI-met micro-meteorological model is adopted to visualize the environmental parameters after field measurement whereas the Ecotect is applied to validate the thermal performance under different design variants. The simulation results show that the thermal performance of geometry and orientation for the transitional space is seasonally discordant. On account of giving consideration to balance the double demands of solar shading in summer and solar gain in winter, a south-oriented transitional space with the windward side enclosure, length-width ratio of 2:1, and aspect ratio with 1.2 produces a greater thermal environment in Tianjin, China. Combined with the previous literature, south-oriented transitional spaces have a comparative advantage in balancing year-round thermal comfort for most cases; the deviation of the preferred orientation in the corresponding cities from the due south orientation is within 90° of a counterclockwise rotation. The lower aspect ratio (approximately below 1), deeper shape, and lower enclosure of the transitional spaces is appropriate for tropical and subtropical areas to avoid excessive sunshine; for temperate climates with hot summers and cold winters, such as in Tianjin, the reverse happens.