Energy performance indicators (ISO 50001)
Energy performance indicators (EnPIs) are the KPIs of your energy management. They show whether your energy performance is improving. Under ISO 50001:2018 , EnPIs are mandatory (chapter 8.2): you define them, report them periodically and compare them with your energy baseline. The NEN publication of the standard describes EnPIs as “quantitative values or measures of energy performance”.
A good EnPI answers the question: are we becoming more efficient? Not “are we using less?” (that can also happen because you produce less), but “are we using less per unit of output?”
What is an EnPI under ISO 50001?
An EnPI (Energy Performance Indicator) is a measurable value that shows how efficiently you use energy. It is almost always a ratio: energy use divided by a relevant unit.
Formula: EnPI = energy use ÷ relevant variable
Examples:
- kWh per product produced
- MJ per m² of floor area
- GJ per FTE
- PUE (total use ÷ IT load)
The EnPI normalises your use. If production grows and your absolute use rises, but your EnPI (kWh/product) falls, you become more efficient. That is what counts.
ISO 50001 EnPIs per sector: practical examples
Production companies
| EnPI | Unit | Typical value | Good target |
|---|---|---|---|
| Electricity per product | kWh/piece | 5-50 kWh/piece | -10% to -20% in 3 years |
| Gas per product | m³/piece | 0.5-5 m³/piece | -10% to -15% in 3 years |
| Compressed air per product | m³ air/piece | 2-20 m³/piece | -15% to -25% in 3 years |
| Specific use | kWh/kg output | 0.1-10 kWh/kg | Depends on the sector |
Example: A metal company measures 12 kWh per produced part. After investing in frequency controllers and compressor optimisation: 10.2 kWh per part. Improvement: 15%.
Data centres
| EnPI | Unit | Typical value | Good target |
|---|---|---|---|
| PUE (Power Usage Effectiveness) | Ratio | 1.4-1.8 | Below 1.3 |
| kWh per rack | kWh/rack/year | 15,000-50,000 | -10% in 3 years |
| Cooling efficiency | kW cooling/kW IT | 0.3-0.6 | Below 0.3 |
| WUE (Water Usage Effectiveness) | L/kWh | 0.5-2.0 | Below 1.0 |
Example: A data centre has a PUE of 1.58. By introducing free cooling and hot/cold aisle containment, the PUE improves to 1.34. Saving: 15% on total energy use.
Office buildings and property
| EnPI | Unit | Typical value | Good target |
|---|---|---|---|
| Electricity per m² | kWh/m²/year | 40-120 kWh/m² | -15% in 3 years |
| Gas per m² | m³/m²/year | 5-15 m³/m² | -15% in 3 years |
| Energy per FTE | GJ/FTE/year | 5-20 GJ/FTE | -10% in 3 years |
| Energy per workstation | kWh/workstation/year | 1,500-4,000 | -10% in 3 years |
Example: An office building (10,000 m²) uses 85 kWh/m². After LED lighting, smart thermostats and daylight control: 68 kWh/m². Improvement: 20%.
Hotels and hospitality
| EnPI | Unit | Typical value | Good target |
|---|---|---|---|
| Energy per overnight stay | kWh/guest night | 15-60 kWh | -10% to -20% in 3 years |
| Gas per overnight stay | m³/guest night | 2-8 m³ | -10% in 3 years |
| Energy per m² | kWh/m²/year | 100-300 kWh/m² | -15% in 3 years |
| Swimming pool per m³ of water | kWh/m³/day | 5-15 kWh/m³ | -20% in 3 years |
How do you choose the right EnPIs for ISO 50001?
Not every EnPI is suitable. A good EnPI meets three criteria:
| Criterion | Explanation | Good example | Bad example |
|---|---|---|---|
| Relevant | Says something about your core activity | kWh per product | kWh per office visitor |
| Influenceable | You can improve the value | kWh per m² (insulation helps) | kWh per degree day (you cannot control the weather) |
| Measurable | You have the data (or can get it) | kWh per building (meters in place) | kWh per customer (hard to measure) |
How many EnPIs do you need?
| Organisation | Number of EnPIs | Explanation |
|---|---|---|
| Small (1 location, homogeneous) | 2-4 | One per energy type plus one overall |
| Medium-sized (several departments) | 4-6 | At least one per SEU |
| Large (several locations) | 6-10 | Per location plus overall |
Rule of thumb: At least one EnPI per significant energy aspect (SEU). If compressors are an SEU, you need an EnPI for compressor efficiency (for example kWh per m³ of compressed air).
Reporting and monitoring EnPIs
Reporting frequency
| Frequency | Suitable for | Advantage |
|---|---|---|
| Monthly | Most companies | Spots deviations quickly |
| Weekly | Energy-intensive processes | Operational control |
| Quarterly | Offices, property | Less administration |
The auditor expects at least quarterly reports. Monthly is better: you spot deviations sooner.
Setting up a dashboard
Your EnPI dashboard shows per indicator:
- Current value (this month or quarter)
- Baseline (reference value from the energy baseline)
- Target (target value from your action plan)
- Trend (line over 6-12 months: is it moving in the right direction?)
Tools: Excel works for small organisations. For medium-sized and larger organisations, consider energy management software (Metrix, EnergyCAP, Power BI dashboards). Costs: €1,000-€10,000 per year.
What do you do when an EnPI deviates?
If an EnPI rises unexpectedly (gets worse):
- Check the data. Is the measurement correct? Is the meter calibrated? Is the production data correct?
- Find the cause. New machine? Change in process? Leak? Fault?
- Take action. Solve the problem or adjust your action plan.
- Document. Record what happened and what you did. The auditor will ask for it.
Common mistakes with EnPIs under ISO 50001
Measuring only absolute use
“We used 480 MWh” is not an EnPI. That is a meter reading. An EnPI normalises: 9.6 kWh per product. Without normalisation, you cannot draw conclusions about efficiency.
Defining too many EnPIs
Tracking 15 EnPIs takes a lot of time and adds little insight. Focus on 3-8 indicators that you actually use for decisions.
Defining EnPIs but not reporting them
You defined good EnPIs at the start, but after six months nobody looks at them. The auditor asks for trend data. Without reporting, that is a finding.
Choosing the wrong normalisation variable
kWh per FTE for a production company says little, because FTEs have little relation to energy use. kWh per product is better. Choose a variable that actually drives the use.
EnPIs and the rest of ISO 50001
| Component | Relation to EnPIs |
|---|---|
| Energy review | Provides the data to define EnPIs |
| SEUs | Each SEU gets at least one EnPI |
| Energy baseline | You compare EnPIs with the baseline |
| Objectives | Targets are expressed as EnPI improvement |
| Audit | Auditor checks whether EnPIs are measured, reported and used |
| Management review | EnPI trends are a fixed agenda item |
More information
- Energy baseline: the reference point against which you compare your EnPIs
- Energy aspects (SEUs): the focus areas for which you define EnPIs
- Energy review: the analysis that provides the data
- Requirements of ISO 50001: what the standard requires on EnPIs
- Step-by-step plan: EnPIs as a step in the overall process
- Costs and timeline: what monitoring and software cost