CESAR-P (Combined Energy Simulation And Retrofitting - Python) is a bottom-up, urban scale building energy modelling (UBEM) package used to simulate the energy demand for a district or region. CESAR-P enriches a set of core inputs (building geometry, type, age, energy system) with typical construction and operation parameters based on values published in the SIA2024 standard (operational) and building statistics (construction materials). An individual simulation model (.idf) is created for each building and simulated in EnergyPlus. Shading from the surrounding buildings is taken into account by including all buildings within a radius specified by the user. CESAR-P also includes a retrofitting module to investigate the impact of retrofitting strategies based on the target and minimum specifications of the SIA380. CESAR-P performs post-processing of the simulation results to calculate the embodied emissions and investment costs of different retrofitting strategies.