With the aging of China's population and the liberalization of the birth policy, the country's social population structure has changed, and the public activity spaces of residential areas are expected to meet the new needs created by such change. According to the existing literature, the most common population group in the public activity spaces in China's current residential areas consists of the elderly with young children. However, how to evaluate the suitability of these spaces from the perspective of sunshine and thermal environments remains unclear. To fill this research gap, this article takes Xi'an as a case to explore the construction of an evaluation index system for sunshine and thermal environment suitability in the public activity spaces of residential areas for the elderly with young children. Firstly, based on field research and literature review, four initial indices were established, including sunshine demand hours, ultraviolet intensity, the universal thermal climate index (UTCI), and the wet bulb globe temperature index (WBGT). Secondly, on the basis of field research and expert interviews, these indices were revised and finalized, mainly with regard to the sunshine and thermal environment suitability for the elderly with young children in the urban residential area, so as to make the indices more in line with the actual research problems. Thirdly, a scoring method for each of the finalized indexes was proposed, resulting in a comprehensive evaluation index system. Finally, the suitability and operability of the constructed index system were validated through practical application in a sample residential area. The results show that, based on some known indices, the evaluation index system of the sunshine and thermal environment suitability of public activity space for the elderly with young children can be established. Its application is potentially helpful in making the public activity space environment in existing residential areas in China more adaptable to the needs of the elderly with young children.
