Environmental Assessment Design and Implementation of Affordable Housing Projects in Nairobi Metropolis, Kenya.

Affordable housing remains a critical development challenge in rapidly urbanizing cities, particularly in developing economies. Nairobi Metropolis continues to experience a persistent housing deficit characterized by project delays, cost overruns, quality compromises, and occasional structural failures, despite sustained public and private sector interventions. This study examined the influence of Environmental Assessment Design as a project design practice on the implementation of affordable housing projects in Nairobi Metropolis, Kenya, and further assessed the moderating role of the Regulatory Framework on this relationship. Anchored on a pragmatist research philosophy, the study adopted a descriptive and explanatory research design, utilizing quantitative methods. Primary data were collected from key stakeholders involved in affordable housing projects, including project managers, consultants, contractors, and regulatory officers. Data were analyzed using descriptive statistics and hierarchical multiple regression analysis to test both direct and moderating effects. The findings revealed that Environmental Assessment Design had a statistically significant positive influence on the implementation of affordable housing projects, explaining 26.9% of the variance in implementation outcomes. When the Regulatory Framework was introduced as a moderating variable, the explanatory power of the model increased substantially to 56.8%, indicating a strong enhancement effect. The interaction between Environmental Assessment Design and the Regulatory Framework was positive and significant, confirming that effective regulatory support strengthened the impact of environmental assessment practices on project implementation. The study concluded that successful implementation of affordable housing projects is not only dependent on sound environmental and technical design but is significantly shaped by the effectiveness of regulatory frameworks. Strengthening environmental assessment processes alongside coherent, well-enforced regulatory mechanisms is therefore critical for improving project delivery. The study recommends enhanced regulatory coordination, streamlined approval processes, and capacity building for project and regulatory institutions. Further research is suggested across other metropolitan counties, with additional moderating variables and longitudinal designs to enrich understanding of sustainable affordable housing implementation.