Simulation-Based Performance Evaluation of a Desiccant Indirect Evaporative Cooling System for Office Buildings in Hot–Humid East African Coastal Climates

In tropical regions like sub-Saharan Africa, conventional vapor compression HVAC systems contribute disproportionately to energy use, operating costs, and carbon emissions—particularly in coastal urban areas where humidity-driven cooling demand is extreme. Despite these challenges, viable low-energy alternatives remain largely underexplored for this region. This study presents the first simulation-based assessment of a desiccant indirect evaporative cooling (DIEC) system optimized for the hot–humid coastal climate of Dar es Salaam, Tanzania, addressing a critical gap in sustainable cooling research for coastal Africa. Using OpenStudio (version 3.9.0) and a custom EnergyPlus(version 9.3.0) latent heat removal algorithm, this study models a DIEC-equipped medium office building with 100% outdoor air ventilation and exhaust-air-based desiccant regeneration. The model reflects local construction practices, occupancy profiles, and weather data and is validated with >90% accuracy against experimental benchmarks. Results demonstrate that the DIEC system (1) maintains indoor thermal comfort (23.8–24.0 °C) during peak humidity periods, and (2) reduces annual cooling energy consumption by 10.2% relative to single-speed DX systems. These savings are particularly impactful in a context where electricity prices are rising, and HVAC loads consume 25–40% of building operational budgets. Furthermore, the system’s superior humidity control and stable power demand make it well-suited for integration with decentralized renewable energy sources. By establishing a context-specific benchmark for DIEC performance, this study delivers a novel, regionally tailored strategy for decarbonizing urban cooling in coastal tropical Africa.