Earthen Building materials to mitigate Urban Heat: An Urban Microclimate and Human Thermal Comfort Study across various neighborhood types

In times of rapid global urbanization, the ability to accurately predict the expansion and impact of urban densification on the local climate is critical to the health and wellbeing of the society. Urban densification is the phenomenon of increasing the number or size of urban structures without increasing urban footprint. The characteristics of urban areas such as- the types of building materials, the geometry or orientation, and the land use zoning including amount of green spaces, all contributes to the urban thermal composition, and intensity of urban warming. However, densification reduces the amount of shade and green or free space per structure, whilst also increasing the paved surface area, thus creating a “heat island (UHI)” due to the mutual heating of building structures and the surrounding infrastructures. In this study, we examine the potential of mitigating the heat island effects through leveraging on thermally massive, low-embodied carbon earth building materials. Such materials have been shown to absorb excess heat, and so may buffer heat island effects whilst simultaneously reducing overall air conditioning energy demands. The effect of adopting these earth materials is examined at the neighborhood scale using state of the earth ENVI-met CFD simulation for urban microclimate and outdoor human thermal comfort modelling. Thus, to understand the consequent impact on neighborhood level changes in urban heat after changing housing materials, the study analyzed different residential neighborhood types (compact, open and sparse low-rise) using the Local Climate Zones (LCZ) classification. Also, various types of earth-based wall construction methods were modelled to evaluate the corresponding impact on the immediate outdoor atmospheric and human thermal comfort conditions. In this contribution, we investigate the hypothetical scenario of replacing conventional cement building materials with traditional earth based alternatives in mitigating emerging UHI effects and show results across different residential neighborhoods.  Ultimately, our findings will help modify construction practices in urbanizing areas to counter urban heat island phenomena effectively.