Green building codes have been implemented in urban areas to promote sustainable development. However, their effectiveness in informal settlements remains largely unexplored. A mixed-methods approach combining quantitative data from surveys and qualitative insights through focus group discussions was employed. Survey results indicated an average improvement of 20% in energy efficiency ratings among green buildings compared to non-green codes, with significant community engagement levels above 75%. The study underscores the potential of green building codes for enhancing housing quality and fostering community participation in informal settlements. Future research should focus on scaling up successful interventions and exploring broader policy implications for other urban settings. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.