Introduction: In hot-arid climates, optimizing window design is crucial for balancing energy and visual comfort, which can affect environmental health and efficiency in educational buildings.
Methods: A single south-facing classroom (8 m × 6 m × 3 m) in Kerman was simulated using DesignBuilder software. Variables included Window-to-Wall Ratio (WWR: 10%–60%), number of windows (1–5), and orientation (horizontal vs. vertical). Energy consumption (site, source, heating, cooling loads) and Daylight Factor (DF) were evaluated for 60 models.
Results: No model with 10% WWR achieved the minimum required DF ( ≥ 2%). With 20% WWR, only 1–2 vertical windows met DF ≥ 2%, with 1 vertical window being optimal (the lowest source energy: 376.82 kW.h). With 30% WWR, 5 vertical windows were optimal (source energy: 383.86 kW.h, DF: 2.609%). With 40% WWR, 5 vertical windows performed best (source energy: 402.33 kW.h, DF: 3.965%). With 50% WWR, 4 horizontal windows were optimal (source energy: 414.41 kW.h, DF: 2.146%). With 60% WWR, 5 horizontal windows were optimal (source energy: 429.48 kW.h, DF: 2.566%). Cooling load had a greater influence on total energy consumption than heating load.
Conclusion: In hot-arid climates like Kerman, vertical windows are more efficient at lower WWRs (20%–40%), while horizontal windows perform better at higher WWRs (50%–60%). The overall optimal configuration was 20% WWR with one vertical window, providing minimal energy consumption, which creates environmental health in terms of daylight comfort.