## 4 Conclusions  
This study presents 12 Lean tools applied in the building design process, identified through a literature review. The collected evidence demonstrates the application or recommendation of these tools in building design projects. Experts confirmed the use of these tools during this stage of the process. Among both sources, tools such as LPS, BIM, VM, and ADM stand out, as they show the highest evidence of application in specific cases and the lowest variability in recommendations. Experts proposed four additional tools, increasing the total number of Lean tools identified for the building design process to 16. Each tool was analyzed to determine if it fulfilled at least one function in the design phase. A comparison between the literature and expert opinions on the number of functions each tool can cover showed that the most valued tools were BIM and LPS, with unanimous agreement from both sources. The tools with the greatest positive discrepancies between the literature and expert opinions were ADM and LAP. At the same time, VSM and SBD showed the greatest negative discrepancies, raising questions about their functionalities. When evaluating functionalities based on the classification of the five management principles, the most significant tools from an organizational perspective, according to experts, were BIM, LPS, and ADM. This is because these tools encompass a broad range of planning, organization, direction, and control functions. The tools that best complement each other in terms of the number of functions they can cover are BIM and LPS. This duo has great potential, as LPS is essential for design planning and control, and if automated and combined with BIM, it could enhance workflow with 3D visualizations and optimize project processes [86]. Another notable duo is ADM-BIM, as Agile Design Management covers functionalities similar to the Last Planner System. Together, these two duos cover 88% of the identified functions. Based on this analysis, the best tools for use in the building design process are the Last Planner System, Agile Design Management, and Building Information Modeling, as they contribute to maximizing value, focusing on the client, and improving information flow [21]. The benefits and limitations of LPS, BIM, and ADM were assessed. The findings suggest that professionals support Agile Design Management, particularly regarding breaking tasks into smaller packages to enhance control and clarity, ultimately improving collaboration. These findings align with [PERSON] and [PERSON] [67]. However, limitations to implementing the tool include the need for training, resources, and resistance to change. As supported by experts, the key advantages of LPS align with the literature: it reduces uncertainty [90] through precise planning and monitoring. It decreases workflow variability [71; 91; 92] due to continuous control in planning. It also ensures reliability in weekly planning and resource commitment [71; 91; 92], refining tasks to guarantee completion. The literature highlights a lack of LPS application in real design cases due to designers' resistance during this phase [87]. Professionals agree that resistance to change is a key barrier, especially when companies fail to perceive the tool's value at this stage, mistakenly considering it relevant only for the construction phase. Experts and professionals agree that Building Information Modeling enhances coordination, early problem detection in projects, information management, visualization, and control. They all recognize the implementation challenges, such as the need for training and team mindset shifts. The literature supports BIM's positive impact on collaboration and communication in design projects [86], consistent with expert and professional opinions. The limitations identified by [86], such as resistance to change and the need for specialized training, align with those mentioned by experts and most professionals. The sustainability of this research lies in its methodological replicability and potential for future extension.