Efficiency measures how effectively a production system uses its available time and resources compared to its full potential. In simple terms, it reflects how much of your scheduled operating time is spent producing good output at the intended rate, without unnecessary interruptions.
An efficiency of 100% means the system is producing only good output, operating at its target speed, and running continuously without downtime. In practice, efficiency helps highlight where time or capacity is being lost due to interruptions, reduced speeds, or other operational constraints.
Tracking efficiency is a common way to identify improvement opportunities and monitor progress over time. By understanding where losses occur, teams can prioritize actions that increase throughput and reduce waste. In many environments, efficiency is measured directly from equipment data, but in ReliaSim® it is evaluated through simulation—allowing you to explore how changes to rates, buffers, and interruptions affect overall system performance before making physical changes.
Efficiency is influenced by three primary factors:
- Availability – The percentage of scheduled time the system is able to run (often referred to as uptime).
- Performance – How fast the system operates compared to its intended speed.
- Quality – The proportion of output that meets requirements. Quality effects can be modeled or applied after simulation, depending on your workflow.
How this relates to OEE
Efficiency is built from the same three factors as OEE — Availability, Performance and Quality — so the two measure the same kinds of loss. What separates them is the denominator: what counts as the time the system could have been producing.
Because of that, a simulated Efficiency and a plant-reported OEE can describe the same shift and still differ by a wide margin, without either being wrong. If you are comparing the two, read Asset Efficiency vs OEE first — it works through where the gap comes from.
In some cases, efficiency is also evaluated against total calendar time rather than only scheduled operating hours. This broader view accounts for how much of the day or year the system is actually planned to run, providing additional insight into overall capacity utilization.
Within ReliaSim, there is a live efficiency gauge reflecting the current conditions included in the top navigation bar.
As interrupts and other changes are made to the model, the predicted efficiency will update to reflect them.