## 3 Research Approach  
Although much research has been done on the application of BIM and Lean paradigms individually, there is a lack of research on the synergy of both paradigms. This is aggravated if we narrow the search to a more practical approach that moves away from theoretical research. The literature review has made us aware that there is hardly any previous practical research that combines both paradigms. Therefore, the aim of this research is to provide knowledge and evidences in a empirical way to this area so little explored, or this, t he study adopted on a constructive research approach with qualitative methodology defined and validated through a case study. Case study is presented in some works as the most appropriate research method for presenting the information in the context of a particular project, inclusive of the project's characteristics and give actual project data, making possible generalisation from case-studies. It is described as a useful method to identify potential benefits of the system, especially those that are intangible, to determine its importance, as well as provide the best correlation with real-life situations. Several studies have already adopted a case study approach, such as in Reference [56], where a case study approach was adopted to explain the dynamic quality control model that was developed from a comprehensive review of the literature and site investigation. Similarly, in Reference [57], BIM benefits and the impacts on project efficiency were analysed via case studies within a large industrial setting where similar projects were evaluated, some implementing BIM and some with traditional, non-BIM approaches. Also, in Reference [58], due to the lack of case studies identified in the literature review, and to provide empirical evidence of the value and challenges of BIM, a case study of Northumbria University's city campus, was used to empirically explore the value and challenges of BIM in facility management. Also, in Reference [59] a case study of BIM deployment in a hospital construction project was developed to serve as an example of BIM implementation and collaborative work in construction projects, in order to provide findings about key factors influential to enable digital collaboration. Furthermore, it is a fairly widespread method to provide empirical evidence on the application of the BIM or Lean paradigms independently. According to the above, the authors adopt this approach, being aware of the limitations of the present research, regarding the need for more empirical observations, which currently make it impossible to carry out a quantitative analysis. The research methodology included three different phases: a first phase defines the problem or deficiency upon review of the literature, a second phase presents the development of the case study carried out in the research and finally a third phase includes the analysis of data obtained and the comparison with data of other public projects. Figure 3 shows the overall research framework adopted by the authors. Figure 3: Overall research framework. The first phase include d the outcomes from literature not only about BIM and Lean construction but also about the BIM and Lean construction synergies. The second phase consisted of a case study where BIM and Lean paradigms were applied during the construction phase of a public building extension, the Multipurpose Building III at The University of Alicante. This research phase included the development of the BIM model during the design phase and its updating throughout the entire construction phase. Also, researchers introduced the Lean construction culture to the construction company, guiding the last planners of the construction companies and subcontracted companies in the application of the Last Planner System, recommending processes derived from literature.