INTRODUCTION: The construction industry, characterized by its hazardous working conditions, particularly in extreme environments such as high temperatures, presents significant challenges for construction workers in mitigating heat-related illnesses (HRIs). METHOD: This study advances the application of evidence-centered design (ECD) in developing an effective heat stress training program for construction and general workers. The methodology encompasses comprehensive steps, including: (1) defining training objectives, (2) determining relevant knowledge domains, (3) designing assessments, (4) providing evidence of training effectiveness, and (5) developing practical tasks using real-world case studies. The training's effectiveness was evaluated through an experimental training session in which 311 construction and general workers participated. The efficiency of the training was measured by calculating short-term, middle-term, and long-term knowledge gains about heat-related illnesses. RESULTS: Statistical analysis revealed significant improvements in workers' understanding of heat stress concepts, risk factor identification, prevention strategies, symptom and sign recognition, and first aid application from the short-term to the middle-term and into the long-term. Trainees' feedback also affirmed the training's effectiveness in enhancing awareness and preparing them to implement preventive measures against heat stress. CONCLUSIONS: The study demonstrates that a heat stress training program utilizing ECD significantly enhances the efficiency of heat stress awareness. These assessments effectively evaluate construction workers' ability to recognize and respond to heat-related hazards. PRACTICAL APPLICATIONS: This finding contributes to the theoretical knowledge of construction worker safety and provides a practical framework for guiding the design of training assessments. The study addresses a gap in literature regarding the assessment of training effectiveness, offering insights for iterative improvement of safety training in construction industry.