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Excess heat in urban environments is an increasing threat to human health and well-being. Furthermore, the increasingly important phenomenon of the Urban Heat Island (UHI) is exacerbating problems of livability in urban centers. Hence, there should be an increasing effort to assess the impact of heat mitigation strategies (HMSs) on outdoor thermal comfort in cities. This research has investigated how urban areas in steppe climate zones can be more thermally comfortable due to the effects of water bodies and trees, and how this might help to mitigate heat waves. Numerical simulations using the ENVI-met microclimate model have been performed for an urban park in Tabriz, Iran. In-situ measurements of air temperature (Ta) and mean radiant temperature (MRT) have been carried out in the study site and the collected data was used to validate the model (RMSE value 0.98 °C for Ta and 5.85 °C for MRT). Results show that water body evaporation without trees may decrease the air temperature, but on the other hand also increases the humidity, which reduces the positive impact on thermal comfort. However, the combination of water body with trees represents a better performance in the regulation of urban microclimate and thermal comfort.

According to population growth, urban sprawl, as well as global warming, attention to the impact of design on thermal comfort in open spaces is important. Thus, it is essential to climate studies and understanding environmental features, as well as results usage in improving designs. The courtyard as open space in residential buildings which is an important factor in the absorption of sunlit in the courtyard surfaces. Therefore, controlling shading performance with regard to thermal comfort condition is one of the most effective factors in reducing the ambient temperature during hot days. This paper focuses on the impact of shading performance in traditional courtyard houses in the hot (Kashan) and cold (Ardabil) climate of Iran. For better understanding four traditional courtyard houses of Kashan and Ardabil selected randomly. By Design Builder software shaded areas were analyzed for each case. The results showed that the best form for the courtyard in these climates is rectangular. The results indicate that increasing the ratio of length to width and also increasing the height of the walls of the courtyard increases the percentage of shading. As conclusion during a day, there is a high correlation between the MRT and the PMV index, and reducing the MRT improve the PMV index.

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