This dataset contains the underling data for the papers: M. Kuzay, A. Dogan, S. Yilmaz, O. Herkiloglu, A.S. Atalay, C. Yilmaz, E. Demirel, Retrofitting of an air-cooled data center for energy efficiency, Case Studies in Thermal Engineering (2022), 36, 102228. https://doi.org/10.1016/j.csite.2022.102228. M. Kuzay, A. Dogan, S. Yilmaz, O. Herkiloglu, A.S. Atalay, C. Yilmaz, E. Demirel, Numerical and experimental dataset for an air-cooled data center, Data in Brief (2022). All cases were prepared using OpenFOAM 8 for the simulation of flow and thermal structures inside the data center for both previous and retrofitted designs. previousDesign.tar.xz: OpenFOAM files and scripts for the simulation of flow and thermal structures in the previous data center design. retrofittedDesign.tar.xz: OpenFOAM files and scripts for the simulation of flow and thermal structures in the retrofitted data center design. experimentalScenarios.tar.xz: OpenFOAM files and scripts for the simulation of flow and thermal structures under the same thermal conditions as in the experimental studies. data.tar.xz: Temperature data obtained from the experimental studies conducted for previous and retrofitted designs.