Investigating the Effect of Blue–Green Infrastructure on Thermal Condition—Case Study: Elazığ, Turkey

This study examines the thermal impacts of green and blue infrastructure in Hilalkent Neighborhood, Elazığ City, in Turkey, using ENVI-met 5.6.1 software. Six design scenarios were proposed and their impact on air temperature, relative humidity, mean radiant temperature (Tmrt), physiological equivalent temperature (PET), and wind speed during August and January was analyzed. The simulation results were verified via field measurements using the Lutron AM-4247SD Weather Forecast Station at a height of 2.0 m above the ground. Data were collected in August 2023 and January 2024. The findings of this study indicate that existing vegetation in the study area provides a cooling effect of 0.8 °C during August. The addition of 10% grass coverage further reduced air temperature by 0.3 °C, while a 20% increase in tree density led to a 0.6 °C temperature reduction. The inclusion of a 10% water surface resulted in a 0.4 °C decrease in air temperature, and the implementation of extensive roof gardens contributed to an additional 0.2 °C reduction during the August period. The combined implementation of blue–green infrastructure in the study area achieved a total cooling effect of 1.5 °C during August. During January, the proposed scenarios led to a reduction in average temperatures by 0.1 °C to 0.4 °C compared to the base scenario, which may not be favorable for thermal comfort in colder conditions. Relative humidity values decreased during the August and Tmrt values were directly proportional to air temperature changes in both August and January. The results of this study provide valuable insights for urban planners and policymakers, demonstrating the effectiveness of blue–green infrastructure in mitigating the urban heat island (UHI) effect. These findings highlight the importance of integrating climate-responsive design strategies into urban planning to enhance thermal comfort and environmental sustainability in cities.