Sebastiaan contributed to the Multi-Energy-Systems-Optimization/mesido repository by optimizing the conversion of hourly energy profiles to daily averages with an hourly peak day, focusing on both speed and scalability. He refactored the core data processing logic in Python, leveraging his expertise in performance optimization to achieve a sixfold increase in processing speed for the adapt_hourly_year_profile_to_day_averaged_with_hourly_peak_day function. This enhancement improved the efficiency of daily profile generation workflows, addressing the need for faster data handling in energy systems modeling. All changes were documented in the project’s changelog, reflecting a methodical approach and a clear focus on maintainable, high-performance code.