Energy KPIs make the energy and emissions consumption of a production process measurable. The two central metrics are kWh per part (energy consumption per manufactured unit) and CO₂ per part (CO₂ emissions caused per manufactured unit). Both combine energy, unit count and energy carrier mix into a single figure that enables objective comparison of lines, plants, products and variants.
kWh per part = energy consumption in kWh in the period divided by number of parts produced. The distinction between good parts and total parts is critical: kWh per good part makes quality losses in energy consumption visible – high scrap rates mean structurally higher energy input per usable part. Meaningful aggregations are line, product family, article and shift.
Typical questions: which product has the highest energy requirement per part? Which line is more energy-efficient for the same product? Does kWh per part actually decrease after process optimizations or only on paper?
CO₂ per part is the logical extension of kWh per part. The calculation follows three steps: determine energy consumption per energy carrier (electricity, gas, compressed air), apply an emission factor per carrier (g CO₂/kWh), divide the sum of all emissions by parts produced. CO₂ per part is therefore the operational entry point into Scope 2 reporting and customer requirements on product emissions.
The minimum requirement is energy data at machine or line level (meter readings in kWh, optionally gas and compressed air), production data with order reference (good parts and total quantities per product and shift) and temporal alignment so that energy and production measurements cover the same period. Without clean IDs and a shared time axis, both data streams cannot be reliably merged – this is the most common weak point in practice.
An MES automatically links energy data from meters and IoT sensors with order and production data, continuously calculating kWh per part and kWh per good part per line, product and shift. Energy KPIs move from a monthly Excel exercise to an operational steering metric in daily management.
Cost and margin analysis by identifying energy-intensive products and variants. Process optimization by comparing process variants not only via OEE but also via kWh per part. Investment decisions by evaluating new equipment through energy and CO₂ effects in addition to capex. ESG proof points for OEMs and CSRD reports. Load management by linking peak loads to specific orders.
What is the difference between kWh per part and kWh per good part? kWh per part divides total energy by all produced units including scrap. kWh per good part divides by actually usable units – making the energy loss from quality problems visible. Measuring only kWh per part conceals quality losses in the energy KPI.
How precise do energy meters need to be? For operational steering, line or area level with good time resolution is sufficient. For CSRD-compliant reports and customer audits, higher granularity and verifiable measurement chains matter more. The pragmatic starting point is kWh per part at line level – then refine step by step.
Can energy KPIs be calculated without MES? Yes – but manually and with considerable effort. Without automatic linkage of energy and production data, Excel exercises arise that are time-delayed, error-prone and difficult to scale. As soon as multiple lines or plants are involved, an integrated solution is the only practical path.