University of Tehran Study Finds No One-Size-Fits-All Solution Across Climates

According to the University of Tehran’s Public Relations Office, researchers conducted a multi-city study examining the influence of human activity intensity on urban thermal comfort in 12 Iranian cities across three climatic groups: humid, semi-arid, and arid. The findings indicate that this relationship is not uniform across all cities, and that climatic conditions play a decisive role in shaping thermal comfort patterns.

The study, titled “Assessing the Human Modification Gradient Influence on Urban Thermal Comfort Variations: A Multi-City Analysis Across Climatic Regimes,” was conducted by Dr. Mohammad Karimi Firozjaei and Dr. Hamide Mahmoodi, faculty members at the College of Management, University of Tehran, and Dr. Jamal Jokar Arsanjani from Aalborg University Copenhagen, Denmark.

To assess the spatial pattern of thermal comfort, the researchers used a combination of satellite imagery, elevation data, a human activity intensity index, and meteorological station data. They then employed a machine learning model to simulate the relationship between thermal comfort and environmental and human factors. Validation tests also demonstrated the high accuracy of the model used.

According to the study’s findings, among the factors examined, land surface radiative components—especially incoming longwave radiation—made the greatest contribution to explaining variations in thermal comfort, followed by albedo and vegetation cover.

The results revealed a clear difference among climatic groups: the thermal comfort index was highest in arid cities and lowest in humid cities. Among the 12 cities studied, Bandar Abbas recorded the highest index value.

In arid cities, a significant portion of the urban area fell into the warm class. In Bandar Abbas, Zahedan, and Kerman, more than 90 percent of the city area was classified in this category, while in Ahvaz, nearly 80 percent fell into this class. In contrast, Isfahan had a different situation, with the majority of its area falling into the comfort class.

The results also showed that built-up areas have a higher thermal index compared with green spaces and water bodies. However, the direction of the relationship between human activity intensity and thermal comfort was not the same across different cities; in some cities, the relationship was positive, while in others, including Bandar Abbas, it was negative. In other words, an increase in human activity intensity does not have the same thermal consequences in all cities, and this relationship must be interpreted within the climatic context of each city.

Dr. Karimi Firozjaei and Dr. Mahmoodi emphasize that examining urban thermal comfort without considering climatic context and human activity patterns cannot provide a complete picture of a city’s thermal conditions. According to them, the findings of this study can help urban planners and managers design and implement heat stress mitigation strategies—including the development of green spaces and the management of urban development patterns—tailored to each city’s climatic conditions.

The article is derived from the research project “Assessing the Impact of Human Activity Change Gradient on Spatial and Temporal Variations of Urban Thermal Comfort: A Multi-City Analysis Across Different Climatic Classes,” which was supported by the Iran National Science Foundation.

The article was published in Remote Sensing Applications: Society and Environment, an Elsevier journal, and its text can be viewed through the following link:

https://www.sciencedirect.com/science/article/abs/pii/S2352938526003927