Assessing Distribution Voltage Behavior Using Time-Series Building Demand: A Building-Grid Co-Simulation Framework

Building electricity demand varies over time due to operational schedules, weather conditions, and equipment usage, and this variability can influence voltage stability in distribution networks. However, grid interconnection and planning studies are commonly conducted based on static peak-load assumptions, limiting the ability to reflect how realistic building operations affect localized voltage behavior. To address this limitation, this study presents a sequential building-grid co-simulation framework that integrates time-series building electricity demand into distribution system analysis. The proposed framework links building energy modeling (EnergyPlus) with distribution-level power-flow simulation (OpenDSS) to evaluate voltage behavior under realistic operating conditions. Hourly electricity demand profiles derived from an IECC reference large office model are applied to the IEEE 34-bus feeder without additional scaling. Voltage performance is analyzed at multiple connection points using statistical metrics, voltage sensitivity indices, and violation duration based on the ANSI C84.1 standard. The results indicate that static peak-based evaluations fail to capture the timing and persistence of voltage deviations under dynamic building operation. Voltage sensitivity and violation duration vary significantly depending on feeder location and electrical characteristics. Nodes located at feeder ends and on secondary feeders exhibit greater voltage vulnerability than those near the substation or supported by capacitor banks. These findings highlight how realistic building operational dynamics influence distributionlevel voltage behavior and demonstrate the importance of incorporating temporal building demand characteristics into building-to-grid evaluation and operational planning.