Building Envelope Renovation for Energy Efficiency in Maputo, Mozambique: Expanded Polystyrene Insulation and Double-Glazed Windows

This study examines the impact of envelope renovation using Expanded Polystyrene (EPS) insulation and double glazing on reducing CO 2 emissions and energy consumption in low-income residential buildings in Mozambique’s tropical climate. Conducted in Maputo over 12 months (2023–2024), it targets urban households, addressing high energy use and emissions caused by inefficient building envelopes and limited access to sustainable technologies. The study uses DesignBuilder’s validated EnergyPlus engine to evaluate energy savings and financial viability within cultural and economic contexts. Results show a 42.16% reduction in energy consumption (from 5392.04 to 3118.69 kWh) and a 42.20% decrease in CO 2 emissions (from 3.27 × 10 3 to 1.89 × 10 3 kg) compared to conventional designs. With an 11.75% discount rate accounting for inflation and opportunity costs, the retrofit achieves a payback period of 6.9 years, confirming its financial viability. These findings offer policymakers, architects, and low-income communities a cost-effective retrofit model, advocating for policy integration of low-U-value materials to improve environmental and economic sustainability.