The rapid urban spatial expansion in many cities around the world has radically increased the need for creating more liveable outdoor green environments for social interactions and recreational activities such as walking and cycling. However, there is always a potential risk of design failure once the outdoor spaces are not fully designed with sufficient attention to the microclimatic conditions of the region. In this line, not responding to the concept of nature conservation can lead to the creation of outdoor spaces with high level of thermal discomfort and considerably low frequency of use. In this research, a quantitative field study is conducted to explore the outdoor thermal comfort conditions of different urban spaces in a hot and humid climate based on Physiologically Equivalent Temperature (PET) thermal comfort index. As a result, guidelines and lessons for environmental education are proposed in order to optimize the design of green urban areas towards enhancing the quality of outdoor life. Findings demonstrate that nature conservation, as part of the urban heat mitigation strategies, considerably improves the thermal comfort conditions. The study concludes that designing climate-responsive green urban spaces, as an indicator of urban sustainability in environmental education, can provide comfort, satisfaction and human health for users in the outdoor spaces while reducing the air conditioning demand in buildings. Keywords� Outdoor Urban Space, Sustainable Development, Thermal Comfort, Nature Conservation, Environmental Education.