Optimum design of hybrid renewable systems is essential for the efficient utilization of the renewable sources and uninterruptible energy supply. The size and backup capacity of the system are effected by the hourly energy demand profile of the building. In this study, optimal design of PV/wind/battery/diesel hybrid renewable energy system (HRES) for the electrification of a hotel building (HB), education building and animal hospital (AH) for on and off grid cases are evaluated to compare buildings with different demand profiles. The hourly electricity consumption of the buildings is measured during January 2023. Nonlinear swarm optimization algorithm was used to minimize the system cost of electricity (COE) and maximize the renewable fraction. Optimal off-grid HRES found to include PV and wind turbine together. AH represented the most stable and highest hourly demand which resulted in minimum COE (0.18 $/kWh and 0.321 $/kWh) for on and off grids. Then annual electricity consumptions of the buildings are equalized to compare buildings with the same annual but different hourly load. On-grid HB found to have minimum COE (0.177 $/kWh) due to the closer hourly demand profile on weekends and weekdays then other buildings. Therefore, on-grid HRES configurations are found to be more cost effective in buildings utilized seven days of the week. However, in off-grid case minimum COE (0.321 $/kWh) was obtained for AH and maximum was found for HB which was due to the peak demands. The result shows that buildings with sudden increases require high battery capacity which results in high COE.