An overview of microclimate simulation tools and models for predicting outdoor thermal comfort

In the last decades, researchers are witnessing an increasing interest among public opinion and global communities regarding outdoor environmental comfort. The number of studies about mitigation strategies for the Urban Heat Island (UHI) phenomenon and the effect of climate change in urban areas has considerably increased, as well as those aimed to assess the effectiveness of urban planning strategies (e.g. implementation of vegetation and building orientation) on the urban microclimate and the outdoor comfort [1]. Actually, indoor thermal comfort is a well-established discipline. However, the outdoor environment is far more complex than the indoor environment because of the wide spatial and temporal variations of meteorological variables, hence the need to define suitable models and indices to assess the outdoor thermal comfort. Such models usually refer to a standing person and take into account how human body exchanges heat with the surroundings, according to the mechanisms thoroughly discussed in Chapter 1 of this book. This chapter briefly discusses some of the main models for the evaluation of the outdoor thermal comfort in urban areas, by also showing principles and features of the main related thermal indices. Then, it presents a description of the main software tools nowadays available to simulate the urban micro- climate and to calculate the above-mentioned outdoor comfort indices. For each software tool, the chapter aims to highlight the main advantages and drawbacks, while also providing hints about their reliability according to the existing literature.