This thesis investigates the design, operation and use of contemporary demountable buildings, and explores how functional performance can be assessed in small-scale examples for public use alongside with their relationship to other design elements. The research focuses on three case studies that do not require a high-technology building environment or complex construction skills. Demountable buildings are defined as those that are transported in a number of parts for assembly on site. Contemporary demountable buildings respond to ecological issues, social impacts, technological innovation and economic demands. They can be used to measure a society’s development in environmental sustainability, innovation and economic growth through various forms. Small-scale demountable buildings fulfil many temporary habitation needs in diverse roles, such as non-emergency transitional housing, ephemeral exhibition buildings and seasonal entertainment facilities. The purpose of examining functional performance is to assess if, and how, the requirements of the design have been achieved. This enables project operators to address functional performance from a public perspective by reflecting on the scope and ambition of their projects. This thesis draws on existing literature to investigate previous and on-going research relating to demountable buildings, including classification, the construction process and project management. It also examines selected existing evaluation methods that cover principles, modelling and computer-based solutions from a wider research area, including Guidelines Developed by City Council and Culture Sectors; Assessment Methods in Humanitarian Response and Methods in Environmental Assessment. The research was conducted by combining both quantitative and qualitative research methods, including field research, case studies, interviews, questionnaires and group discussions. Fragmented narratives were transformed into structured evidence, identifying models of best performance in demountable buildings and developing a new method – the Evaluation Conceptual Model – for the effective evaluation and evidencing of the value of demountable buildings in the 21st century. Recommendations for adapting a suitable model to evaluate other design elements in demountable buildings and other types of moveable buildings in further research are suggested and the findings have been used to lay the foundations for a practical evaluation tool for the future