Cities are facing significant challenges related to climate change, particularly due to the increasing impact of the Urban Heat Island (UHI) phenomenon. The present study investigated the UHI phenomenon at the microscale in Annaba, Algeria. The research involved a multi-step approach, starting with on-site measurements of urban microclimate parameters, performed in downtown Annaba on 6 July 2023. The UHI intensity was quantified by comparing city-measured temperatures with rural surroundings. Thermal imaging is then used to empirically identify the contributing factors to UHI initiation at the microscale. The study employed the ENVI-met model to analyse mitigation strategies, manipulating parameters for six scenarios including the current design of the study area. Outputs were used to assess the impact of these strategies on air temperature, mean radiant temperature, relative humidity, and wind speed. The findings revealed an intense UHI effect in Annaba city with a peak difference of 6.9 °C, with practical implications for buildings, ground and roads, vehicles, air conditioners, and specific facade materials. Introducing urban vegetation, particularly urban trees and green roofs, proved highly effectiveness in mitigating the UHI in downtown Annaba. Urban trees demonstrated the most substantial impact, reducing temperatures by 1.9 °C at 1 p.m., while green roof temperature reductions ranged from 0.1 °C to 2 °C.

Bioclimatic design is a design process that takes into account climate and environmental conditions when designing for optimum thermal comfort with minimum outside energy use. The present study intends to highlight the role of the bioclimatic analysis in design operations at both, urban and architectural scale in Guelma city, Algeria. As our challenge is to provide a precise analysis of the climatic conditions, we have resorted to several methods and bioclimatic tools using climatic data from the decade from 2008 to 2017. Each tool consists of presenting and following the intersection of one or more climatic parameters with respect to time. As a result, we have located the bioclimatic floor to which Guelma city belongs, the overheating, the under heating and the comfortable zones have been determined. The findings are significant to draw up the main recommendations and requirements for a bioclimatic design for Guelma city in particular and for regions with semi-arid climate in general.