The public spaces in our today’s lives involve many sorts of activities, and the design of such spaces requires a wide range of studies. One of the critical studies in our country, due to its climatic variety, is about the thermal comfort of public outdoor spaces. This article has been conducted to investigate about possible architecture and landscape architecture design measurements which could contribute to improve the outdoor thermal comfort in residential complexes. Thermal comfort in outdoor settings has received very little research attention. Most researches work concerning thermal comfort has been focused on indoor spaces. The outdoor thermal comfort is measured through the mean radiant temperature (Tmrt) and the physiological equivalent temperature (PET) index. Measuring the thermal differences between the indoor and outdoor spaces require different methods of investigation. In order to investigate the mean radiant temperature (MRT), one should know the air temperature, humidity, wind speed, and the direct or indirect radiation levels. On the other hand, in order to investigate about the physiological equivalent temperature (PET), one should know about the age, the gender, the type of clothing, and the type of activities in which the people are involved with. This paper investigates about the thermal comfort of six outdoor public spaces within the Ekbatan residential complex, Phase III, by applying ENVI-Met 4 software which is based on a three-dimensional and energy balance model. In the first stage of the investigation, by the use of simulation method, the mean radiant temperature, Tmrt, of six different locations were measured. Then, the thermal comfort of physiological equivalent temperature (PET), was calculated in those locations for a designated individual group during the middle days of the four seasons. In the final stage of the research, using a comparative method, the physiological equivalent temperature (PET) and the environmental physical factors, such as sky view factor (SVF), the level of shading, the distance between the outdoor space and the building were identified as major design criteria in order to improve the thermal comfort of those outdoor spaces. Analytical results show that there is a sensible correlation between growing sky view factors (SVF) and falling physiological equivalent temperature (PET). The findings of the research indicate that although the shadow of obstacles cause decrease of air temperature throughout the year, during the warm days of summer afternoons, the air temperature in shadows near the buildings increase due to the radiation of heat from the masonry obstacles. Hence designers should consider locating summer activities far from the buildings. Different shading levels and various shading patterns are suggested to let users to choose their preferred conditions. Chosen colors and materials of surrounded surfaces should absorb solar radiation slightly in order to avoid increasing mean radiant temperature (Tmrt) through reflected radiation from the surfaces. The location of the evening and morning activities are recommended to be placed near the buildings in the cold months in order to benefit from the transmitted heat through the inside spaces and buildings. The paper concludes with some suggestions about how to improve the thermal comfort of the outdoor spaces through the use of proper architectural design planning.