6. Conclusion
Green architecture suffers from a lack of quantitative cost-benefit studies to accelerate their application and use. Unfortunately, the lack of clear and systematic research studies of building costs have resulted in the ambiguity of green building cost-benefits. This research aimed to draw attention to the importance of research methodologies and compared advantages and disadvantages of each method for calculation of different cost variables. This research reviewed only the mainstream methods for green cost-benefit predictions. The reviewed papers are inclusive of the most validated research works in the field, but not exclusive to quantitatively comparing the applications of different methods. A systematic quantitative literature review [46] is then recommended as future studies for further investigations and explorations of existing methods. Empirical experiences based on objective and subjective studies in real buildings have the benefit of experimental controls and internal validity of research design. However, the production of such detailed and accurate cost-benefit data is a demanding and time-consuming process. In addition, many contextual and non-contextual factors influence the cost-benefits of green buildings, which means the generalisation of findings based on a few building cost performances is not externally validated. Data collection from a secondary source, by being less time-consuming and demanding, have the benefit of larger sample collection possibilities and enhancing external validity.
