# A Review of Indoor Air Quality in Social Housing Across Low- and Middle-Income Countries
## 3 Results of the Literature Survey
### Retrofit and Maintenance (R&M)
Additionally, the research further highlighted the importance of using sustainable, low-emission materials such as EPS and sprayed polyurethane foam (applied at 4 cm for walls and 8 cm for roofs) in retrofits to optimize energy efficiency while supporting IAQ. [PERSON] and [PERSON] [47] continued their work by evaluating the effectiveness of various low-cost filter materials incorporated into a dynamic hybrid air-permeable ceiling (DHAPC) system. Building on an earlier study [37] that focused on reducing particulate matter, this follow-up research incorporated low-cost filters achieving pollutant reductions of up to 90%, targeting PM2.5, SO2, and benzene. Furthermore, [PERSON] et al. 's study and their follow-up [48; 49] investigated closed-vertical voids with pilotis (or horizontal open spaces created by lifting the building with structural columns) and wind fins in tropical double-loaded corridor apartments. They optimized ventilation, increasing airflow by 30% using wind tunnel experiments and CFD modeling. Cooling strategies are a key factor for IAQ and occupant satisfaction in warmer climates. [PERSON] et al. [50] found that NV in Indonesian public rental housing (Rusunawa) reduced energy consumption while achieving over 80% occupant satisfaction. Approximately 60% of households practiced daytime window ventilation, highlighting NV's cost-effectiveness and alignment with low-income housing needs. In Mexico, [PERSON] et al. [51] used multi-objective optimization to reduce cooling energy demand, from 223 kWh/day to 154 kWh/day. Their strategies included building orientation adjustments, improved insulation, and solar shading devices, significantly enhancing airflow and energy efficiency. Similarly, [PERSON] et al. [52] used computational models to evaluate various ventilation strategies in Brazilian social housing and found that continuous window openings were the most effective way to increase comfort hours by 3.28%. [PERSON] et al. [53] showed the importance of cross-ventilation in Indian social housing prototypes, designed by the Indian architect [PERSON], reducing operative temperatures by up to 3.1 \({}^{\circ}\)C on the hottest day and discomfort hours by 77.8% and showing the effectiveness of passive cooling strategies in improving IAQ and thermal comfort. In Honduran social housing, researchers conducted simulations to assess indoor overheating risks, identifying natural ventilation, particularly at five air changes per hour (ACH), as crucial in preventing overheating in both current and future scenarios [54]. However, the study also found that factors, such as high wall absorptance, large unshaded windows, and high solar heat gain coefficients, negatively impacted thermal comfort and IAQ. There are some limitations and potential biases. Simulations often assume idealized or static conditions, which may not fully capture real-world variability, such as occupant behavior or environmental factors like seasonal changes. Moreover, the focus on specific climates, such as tropical or warm-humid regions, limits the generalizability of these findings to colder or temperate zones.