ISO 50001 · Step-by-step series · Clause 10
ISO 50001:2018 Clause 10: Nonconformity, Corrective Action and Continual Improvement of the EnMS
Clause 10 closes the PDCA cycle of ISO 50001:2018. After planning the energy policy and objectives (clauses 4-6), operating the energy management system or EnMS (clause 8), and checking performance through monitoring, measurement, analysis and internal audit (clause 9), clause 10 requires organizations to "act": fix what isn't working and continually improve both the management system and actual energy performance. This guide explains how to run a nonconformity through the EnMS from detection to closure, what separates improving energy performance from improving the management system itself, and how to avoid the most common mistake — closing corrective actions without ever verifying that energy consumption or the EnPIs actually improved.
ISO 50001:2018 is the only management system standard that requires proof of actual performance improvement, not just system improvement
Unlike ISO 9001 or ISO 14001, where continual improvement mainly targets the effectiveness of the management system, ISO 50001:2018 clause 10.2 explicitly requires "continually improving the suitability, adequacy and effectiveness of the EnMS" AND, separately, improving energy performance — the measurable results related to energy efficiency, energy use and energy consumption. An EnMS can be flawlessly documented and still fail to meet the standard if the EnPIs show no improvement in energy performance against the energy baseline.
Structure of clause 10 in ISO 50001:2018
- 10.1 Nonconformity and corrective action: the full process when something fails to meet an EnMS requirement — from immediate reaction to closure with verified effectiveness.
- 10.2 Continual improvement: the organization must continually improve the suitability, adequacy and effectiveness of the EnMS, and demonstrate improvement of energy performance, consistent with the energy policy and based on the results of monitoring, measurement, analysis, internal audit and management review.
Note that ISO 50001:2018 reversed the order used in ISO 9001:2015: nonconformity and corrective action is subclause 10.1 (not 10.2), and continual improvement is 10.2 (not 10.3). A small numbering detail, but worth knowing when auditing against the exact text of the standard.
10.1 The full cycle of nonconformity and corrective action
An EnMS nonconformity can surface through many channels: an EnPI deviating from its energy baseline, a significant energy use (SEU) consuming more than expected, an internal audit finding, a calibration issue on a metering device, or failure to meet an applicable energy-related legal requirement. Whatever the source, the process required by the standard has six elements:
The 10.1 cycle in 6 steps
- React: take action to control and correct the nonconformity, and deal with the consequences (for example, recalibrating an energy meter that was giving faulty readings).
- Evaluate the need for action: determine whether similar nonconformities exist, or could potentially occur, by reviewing and analyzing the nonconformity.
- Investigate the root cause: determine the causes of the nonconformity — for example, through root cause analysis of an energy deviation detected during monitoring (clause 9.1).
- Define the corrective action: implement any action needed to eliminate the root cause and prevent recurrence.
- Review effectiveness: verify that the implemented corrective action was effective — the affected EnPI or SEU has returned to the expected range and the nonconformity has not recurred.
- Update the EnMS if needed: make changes to the energy management system, including, where applicable, the energy baseline, EnPIs or energy planning (clause 6).
Typical sources of nonconformity in an EnMS
Unlike a quality system, where nonconformities usually originate in products or processes, an EnMS has its own nonconformity profile tied to the energy nature of the system:
Practical example — root cause of an EnPI deviation
Nonconformity: the compressed-air line EnPI (kWh/m³ of compressed air) runs 14% above the energy baseline value for two consecutive months.
Why 1? Because compressor working pressure was raised from 7 to 8 bar without a documented change record.
Why 2? Because the maintenance team raised the pressure to compensate for leaks in the distribution network.
Why 3? Because there is no periodic compressed-air leak detection and repair program within the SEU's energy action plan.
Root cause: the energy action plan (6.2) does not include periodic compressed-air leak checks as an operational control for the "air compression" SEU, which allowed an uncontrolled performance compensation via pressure increase — the least efficient way to solve the problem.
Nonconformity and corrective action record — documented information required by 10.1
| Field | Required content | 10.1 reference |
|---|---|---|
| Nature of the NC | Description of the nonconformity and the affected SEU, EnPI or energy-related process | 10.1.a |
| Actions taken | Actions to control and correct the consequences (e.g. recalibration, immediate operational adjustment) | 10.1.a |
| Results of the corrective action | Root cause analysis, evaluation of the need to extend the action to similar SEUs | 10.1.b-d |
| Effectiveness verification | Objective evidence that the root cause was eliminated and the EnPI/SEU returned to the expected range | 10.1.e |
| Changes to the EnMS | Update of energy baseline, EnPIs, action plan or operational controls, where applicable | 10.1.f |
10.2 Continual improvement: system and energy performance are two different things
Clause 10.2 requires two distinct types of improvement that should not be conflated:
- Improving the EnMS as a system: processes, documentation, competence and controls becoming increasingly suitable, adequate and effective — the same type of continual improvement required by ISO 9001 or ISO 14001 for their own management systems.
- Improving energy performance: the measurable results related to energy efficiency, energy use and energy consumption actually improving against the energy baseline, evidenced through the EnPIs. This is ISO 50001's differentiating and more demanding requirement compared with other management system standards.
It is entirely possible to have a mature, well-documented EnMS with favorable internal audits and still fail 10.2 if the EnPIs show no sustained improvement in energy performance over time. That's why certification auditors routinely ask for the historical EnPI series against the baseline, not just the management system manual.
Tools for continual improvement of energy performance
- Periodic energy review (6.3): repeating the analysis of energy use and consumption at defined intervals to identify new improvement opportunities — not a one-off exercise done only at implementation.
- Updating the energy baseline: when EnPIs no longer reflect the organization's performance (significant changes in processes, usage patterns or facilities), the baseline must be adjusted following the methodology defined in 6.5, with the reason for the adjustment documented.
- Prioritizing improvement opportunities: keeping a living register of improvement opportunities identified during energy reviews, prioritized by savings potential and feasibility — not only the ones already in the current action plan.
- Energy benchmarking: comparing EnPIs against similar facilities in the sector or against the organization's own historical data from prior years to put improvement into context.
- Energy-efficient design (8.2): building energy performance criteria into the design of new or modified facilities, equipment, systems and processes, so improvement is built in from the start rather than only corrected afterwards.
How 10.1 relates to the risk-based thinking in clause 6.1
Like ISO 9001:2015, ISO 50001:2018 adopted risk-based thinking and no longer has a separate "preventive action" subclause. Clause 6.1 requires determining the risks and opportunities that need to be addressed to ensure the EnMS can achieve its intended results, prevent or reduce undesired effects, and achieve continual improvement of energy performance. In practice:
- Corrective action (10.1): responds to a nonconformity that has already occurred — an EnPI that already deviated, an SEU that already consumed above the expected value.
- Risk and opportunity management (6.1) — the new "preventive action": proactively identifies what could cause an EnPI to fail or energy performance to degrade before it happens, and what energy improvement opportunities exist. It serves exactly the function the old "preventive action" used to serve.
// IgeraIndustria demo — EnMS tracking (ISO 50001)
Energy Manager: Which EnPIs are outside the expected range against the baseline this quarter?
IgeraIndustria: 2 EnPIs deviated from the energy baseline (Q2 2026). EnPI-03 Compressed air (kWh/m³): +14% vs. baseline, deviation detected 2 months ago, no corrective action recorded with closed effectiveness verification. EnPI-07 Building 2 HVAC (kWh/m²·month): +9% vs. baseline, coincides with a floor-area expansion not yet reflected in the baseline adjustment (6.5). Recommended action: open a formal NC for EnPI-03 under 10.1 and evaluate a baseline adjustment for EnPI-07.
Internal EnMS auditor: Which EnMS corrective actions remain open without effectiveness verification?
IgeraIndustria: 1 corrective action open without effectiveness verification: CA-EnMS-009, source: compressed-air EnPI deviation, due date 15/07/2026 — overdue by 22 days, owner: maintenance. No recorded evidence of a compressed-air leak survey. Recommended action: request a status update from maintenance or escalate to energy management review.
Frequently asked questions about ISO 50001:2018 clause 10
How does ISO 50001's clause 10 differ from ISO 9001's or ISO 14001's?
The high-level structure (Annex SL) is the same across all three standards: nonconformity and corrective action, plus continual improvement. The difference is in 10.2: ISO 50001:2018 explicitly requires demonstrating measurable improvement in energy performance (through EnPIs against a baseline), not just improved effectiveness of the management system. It's a results requirement, not only a process requirement.
Does every EnPI deviation require a formal nonconformity?
Not necessarily. The standard requires corrective action when the organization determines it is necessary to eliminate the cause of a nonconformity and prevent recurrence. Small fluctuations within an EnPI's normal variability range (seasonal effects, for example) don't always constitute a nonconformity. The decision should be based on objective criteria the organization defines in advance — typically a sustained-deviation threshold against the baseline, not a single reading.
When should the energy baseline be updated instead of opening a corrective action?
When the EnPI deviation isn't caused by a system failure but by a legitimate, documented change in the variables affecting consumption — a facility expansion, a significant change in product or process, or new static factor conditions. In that case, clause 6.5 requires adjusting the baseline using the defined methodology, rather than chasing a "root cause" that isn't actually a system failure.
What evidence does a certification auditor look for under 10.2?
Typically the historical EnPI series against the energy baseline across several periods, the register of improvement opportunities identified during energy reviews and their implementation status, and evidence that management review has analyzed energy performance and made decisions accordingly. An EnMS with no EnPI trend data will struggle to demonstrate compliance with 10.2, however well the rest of the system is documented.
What if energy performance worsens in a given year despite having an EnMS?
It doesn't automatically mean nonconformance if the organization can show the system is operating correctly, that improvement opportunities were identified and prioritized, and that there are objective reasons (an uncontrollable production shift, for example) explaining the result. What does generate a nonconformity is the absence of a systematic process to review performance and act on deviations — the standard requires evidence of an active improvement process, not a guarantee of improvement in every single period.
Do your EnPIs drift without anyone noticing until the audit?
IgeraIndustria indexes your energy baseline, your EnPIs and your EnMS action plans, and flags when a deviation needs corrective action before it turns into an audit nonconformity.
See the ISO 50001 solutionIgeraIndustria Energy Team · Updated 2026-08-06 · ISO 50001 step-by-step series: EnMS document management · Industrial energy efficiency