Evaluating the Impact of Building Morphology on Cost Optimization in Residential Projects in Sri Lanka: A RIBA Plan of Work 2020–Based Framework

The construction cost of residential buildings can be managed effectively by optimizing building morphology factors while enhancing functionality and performance. This study aims to enhance the cost efficiency of residential building projects by analyzing the application of building morphology factors across different stages of construction as suggested by the Royal Institute of British Architects (RIBA) Plan of Work 2020. The study encompassed a mixed research approach, which included a questionnaire survey and expert interviews. Quantitative data were analyzed using SPSS statistical software and the relative importance index, whereas manual content analysis was used to analyze qualitative data. Findings ranked the most cost-significant building morphology factors as height of the stories, size, and plan shape, successively. The study revealed the effectiveness of incorporating building morphology factors across the concept design, spatial coordination, technical design, and preparation and briefing stages in alignment with the RIBA Plan of Work 2020. Accordingly, it contributes to the theory by filling the limited body of knowledge on the intersection of morphology factors and cost optimization in residential projects, while providing a benchmark for further research.