Urban heat island mitigation strategies for enhancing energy efficiency in tropical cities; a multi-criteria approach

This study examined urban heat island (UHI) mitigation strategies for enhancing energy efficiency in tropical cities, using Abuja, Federal Capital Territory, Nigeria, as the study area. The study was motivated by increasing urbanisation, vegetation loss, expansion of impervious surfaces, rising temperatures, and growing dependence on mechanical cooling in tropical urban environments. A descriptive survey research design was adopted, and data were collected through structured questionnaires administered to residents, building users, and relevant professionals in selected locations within Abuja. A sample size of 384 respondents was determined using Cochran’s formula, while descriptive statistics, Pearson correlation, multiple regression, and a multi-criteria decision-making approach were employed for data analysis using SPSS. The findings indicate that respondents strongly perceived vegetation loss, concrete and asphalt surfaces, building density, and inadequate air circulation as major contributors to UHI. Urban trees and vegetation, cool roofs, shading, natural ventilation, reflective surfaces, and improved urban morphology were identified as important mitigation strategies. The multi-criteria assessment ranked urban trees and vegetation as the most preferred overall strategy, while regression results indicated significant positive relationships between UHI mitigation measures and energy efficiency. The study concludes that integrating green infrastructure, passive building design, reflective materials, and improved urban planning can reduce urban heat and cooling-energy demand. It recommends incorporating UHI mitigation into urban planning, building regulations, climate adaptation, and energy-efficiency policies in tropical cities.