Introduction/Background Design of clinical areas requires consideration of intended use and workflow. Traditionally, clinical areas are designed from blueprints based on the functional content wish list of the clinical department. Lean methodology is used to reduce or eliminate wasted time, money and energy resulting in efficient, patient-focused systems. Lean focuses on systems, processes and environment, making it ideal for identifying latent conditions for medical error. High fidelity simulation offers the opportunity to evaluate clinical design from the idea stage through construction and eventual occupancy. Using multi-patient, multi-modal in-situ simulation layered with Lean and human factors frameworks and PDSA cycles, we conducted post construction testing of two new clinical spaces in a large academic pediatric tertiary care center. Methods A multidisciplinary steering group determined testing objectives through stakeholder focus groups and leadership interviews. Introductory lean and human factors prebriefing and training sessions were held for participants and observers. A 4 hour simulation was held for a 33 bed ED and a 5 hour simulation was held for a 12 bed PICU. Simulations were fully staffed with pan-disciplinary teams, both simulations interacted with the normally functioning hospital. Simulations were multi-modal with standardized patients and family members, low to high fidelity manikins and task trainers. Trained observer teams and simulation participants collected qualitative data using standardized collection tools. Observers included hospital leadership, front line staff and patient safety staff and physicians. Transcribed structured team debriefs ensured additional feedback on equipment, environment, process and work flow. Over 200 discrete issues identified in each of the simulations. Forty eight consolidated items requiring either a process or environmental change in the PICU simulation, 38 in the ED simulation. A subset of the consolidated items were classified as critical requiring process or environmental changes prior to the move to the new spaces. Simulation guided the orientation and education for the new clinical spaces and highlighted further areas for focused simulation-based testing. Results: Conclusion In-situ simulation can be used to evaluate environment and process to detect latent PST in new environments. Lean and human factors offer a structured framework to conduct in-situ simulations and analyze data. References 1. Hamman, W. R., Beaudin-Seiler, B. M., Beaubien, J. M., Gullickson, A. M., Gross, A. C., Orizondo-Korotko, K., Fuqua, W., & Lammers, R. (2009). Using in situ simulation to identify and resolve latent environmental threats to patient safety: Case study involving a labor and delivery ward. J Patient Saf, 5(3),184-187. 2. Kobayashi, L., Shapiro, M. J., Sucov, A., Woolard, R., MD, Boss R. M., Dunbar, J., Sciamacco, R., Karpik, K., & Gregory J. (2006). Portable advanced medical simulation for new emergency department testing and orientation. Academic Emergency Medicine, 13, 691-695. 3. Going Lean in Health Care.IHI Innovation Series white paper. Cambridge, MA: Institute for Healthcare Improvement; 2005. (Available on www.IHI.org). 4. Berwick D, Hackbarth A. Eliminating Waste in US Health Care. JAMA. 2012;307(14):1513-1516. Disclosures None.