Indicateurs de performance énergétique (IPE) : guide complet

What is an energy performance indicator (EnPI)?

An energy performance indicator (EnPI) is a measure of how efficiently a company uses energy to carry out a given activity. Unlike a raw consumption figure expressed in kWh, an EnPI relates that consumption to a representative variable such as the number of units produced, the tonnage processed or the heated floor area. It shows how a site actually performs, tracks that performance over time and reveals drift quickly [3].

The main families of energy indicators

EnPIs take several forms [4]:

• ●
  Absolute indicators: total electricity, gas or steam consumption.
• ●
  Specific indicators: consumption per unit produced (kWh/tonne, kWh/unit, kWh/m³).
• ●
  Normalised indicators: consumption corrected for the effects of weather, production or other influencing variables.
• ●
  Efficiency indicators: the energy efficiency of a piece of equipment or a process.

Why monitor energy performance indicators in industry?

Monitoring EnPIs is a key lever for lasting improvement in industrial performance. By measuring energy performance indicators regularly, companies can identify consumption drift, assess how effective their actions have been, compare performance over time and guide their investment decisions [5]. These indicators also open the way to ISO 50001 certification [6].

Reducing energy consumption

The first purpose of an EnPI is to reveal energy waste. An unusual rise in specific consumption can point to poorly adjusted equipment, a leak or process drift well before it shows up on the energy bill [7].

Identifying energy drift

Comparing current indicators with a reference period quickly reveals operating discrepancies [8]. This continuous monitoring makes corrective action easier before excess consumption becomes significant.

Reducing operating costs

Energy is often a major cost item in industry [9]. By optimising consumption through EnPIs, companies lower their operating costs while improving profitability.

Improving industrial competitiveness

A plant that uses less energy produces the same output with fewer resources. This gain in energy productivity becomes a lasting competitive advantage [10].

Reducing CO₂ emissions

Cutting electricity, gas or steam consumption directly reduces greenhouse gas emissions, an issue that has become strategic for many companies [11].

Meeting regulatory requirements

Energy indicators also make compliance with a range of obligations easier:

• ●
  BACS decree [12];
• ●
  Tertiary decree [13];
• ●
  CSRD [14];
• ●
  mandatory energy audits [15];
• ●
  ISO 50001 certification [16].

They provide reliable data to demonstrate the progress achieved and to steer action plans.

How to build a good energy performance indicator?

Designing an EnPI follows a structured method. It consists of selecting an indicator that represents energy performance, establishing an energy baseline (EnB) as a point of comparison, then factoring in the influencing variables likely to affect consumption, such as production levels, weather conditions or occupancy rates. The calculation method, the data sources and the monitoring arrangements are documented as well, so that results remain reliable, consistent and comparable over time [17].

Identifying significant energy uses (SEUs)

The first step consists of identifying the areas that account for the largest share of consumption: industrial furnaces, air compressors, chillers, production lines, HVAC systems or utilities.

These uses become the priority for energy monitoring [18].

Setting energy objectives

Each indicator answers a specific objective [19]:

• ●
  reducing consumption in a workshop;
• ●
  improving the efficiency of a piece of equipment;
• ●
  lowering compressed air consumption;
• ●
  tracking the savings generated by a project.

Choosing the right variables

To be representative, an EnPI integrates the factors that naturally influence consumption:

• ●
  production level;
• ●
  weather;
• ●
  operating hours;
• ●
  occupancy rate;
• ●
  tonnage produced;
• ●
  volume manufactured.

This normalisation avoids reading a simple increase in production as drift [20].

Setting a reference period

The energy baseline is the point of comparison for future performance. It usually corresponds to a representative period of operation [21].

Setting up continuous monitoring

Manual readings quickly show their limits. Automated monitoring provides reliable, recorded data that can be used almost in real time [22].

The main energy performance indicators in industry

Energy performance indicators are defined according to significant energy uses, the processes in place and the performance objectives of each organisation [23]. The ISO 50001 standard does not prescribe specific indicators: it recommends selecting EnPIs suited to the activities, the equipment and the variables that influence energy consumption [24].

• ●
  Production: energy consumption per unit produced, kWh/tonne or kWh/unit;
• ●
  Electricity: total electricity consumption, kWh;
• ●
  Gas: natural gas consumption, kWh GCV or MWh;
• ●
  Compressed air: energy consumed per m³ of compressed air, kWh/m³;
• ●
  Boiler: boiler efficiency, %;
• ●
  Steam: steam consumption per tonne produced, t steam/tonne or kWh/tonne;
• ●
  Industrial refrigeration: COP of the chiller units;
• ●
  Electric motors: motor efficiency, %;
• ●
  Industrial building: energy consumption per floor area, kWh/m²/year;
• ●
  Lighting: lighting consumption, kWh/m²/year;
• ●
  HVAC: HVAC system consumption, kWh;
• ●
  Emissions: CO₂ emissions per unit produced, kg CO₂/tonne.

How to measure and analyse EnPIs?

The quality of the indicators depends directly on the quality of the data collected [25].

The main technologies used are [26]:

• ●
  smart meters;
• ●
  energy sub-metering;
• ●
  IoT sensors;
• ●
  industrial PLCs;
• ●
  SCADA systems;
• ●
  EMS (Energy Management System).

Once the data is available, it feeds an energy dashboard used to:

• ●
  compare performance against the baseline;
• ●
  detect anomalies;
• ●
  identify drift;
• ●
  prioritise corrective action.

Automating this analysis considerably reduces the time spent on energy monitoring while improving how quickly teams can react [27].

Common mistakes to avoid

Some practices sharply limit the value of EnPIs. The main mistakes are [28]:

• ●
  monitoring too many indicators without a clear objective;
• ●
  relying on energy invoices alone;
• ●
  failing to normalise consumption against activity levels;
• ●
  overlooking production variations;
• ●
  keeping data collection entirely manual.

A limited number of well built indicators, by contrast, often gives a far more relevant picture of energy performance.