The Volt‑Ampere Reactive Hour (symbol VAR·h or kVAR·h) is the standard unit for measuring reactive energy—the portion of electrical power that oscillates between source and load without performing useful work. It quantifies the cumulative effect of reactive power (measured in VARs) over time, making it essential for tracking energy consumption in inductive and capacitive systems such as motors, transformers, and HVAC equipment. Utilities and industrial facilities use VAR·h readings to assess power factor correction needs, calculate demand charges, and optimize system efficiency, while engineers rely on this metric to design and analyze electrical networks, ensuring reliable operation and compliance with grid standards. By accurately accounting for reactive energy, the VAR·h helps reduce losses, lower electricity costs, and support sustainable power management in both practical applications and scientific research.