Standards & methodology
ISO 50002
ISO 50002
The international standard for energy audits — how to systematically find where energy is wasted, rank improvement opportunities, and collect the baseline data verification needs later.
Scope and structure
ISO 50002 (Energy audits) sets requirements for the systematic examination of energy use in any organisation, building, or industrial process. The audit is the starting point of the energy management lifecycle — its outputs feed directly into ISO 50001 energy reviews, ESCO project scoping, and M&V baseline development.
The standard is published in three parts:
| Part | Scope |
|---|---|
| ISO 50002-1 | General requirements for any audit, any sector |
| ISO 50002-2 | Buildings — envelope, HVAC, lighting, and services |
| ISO 50002-3 | Industrial and manufacturing processes |
EU regulatory context
Under EU Energy Efficiency Directive Article 8, large enterprises must undergo energy audits every four years — unless they hold ISO 50001 certification. ISO 50002 provides the methodology framework many member states reference for compliant audits.
What an audit examines
1. Energy supply and procurement — energy types, tariffs, and supply-side opportunities.
2. Building envelope (ISO 50002-2) — heat loss and gain through the structure; impact on heating and cooling demand.
3. HVAC systems — boiler and chiller performance, distribution losses, controls, and sensitivity to outdoor temperature.
4. Lighting and plug loads — efficiency, daylight controls, and equipment scheduling.
5. Process systems (ISO 50002-3) — motors, compressed air, steam, and process-specific energy intensities normalised against production output.
Audit depth levels
| Depth | Also called | Typical accuracy |
|---|---|---|
| Preliminary | Walk-through / Level 1 | ±25–30% |
| Detailed | Level 2 / Energy survey | ±10–15% |
| Investment-grade | Level 3 / IGA | ±5–10% |
Typical use:
- EU EED compliance: Level 2
- ISO 50001 energy review: Level 2 minimum
- ESCO contracts with payment tied to verified savings: Level 3
The accuracy target chosen at audit stage sets the uncertainty bar for the subsequent M&V plan. Performance contracts commonly target ±10% at 90% confidence.
Audit deliverables
A compliant ISO 50002 audit produces:
- Energy consumption profile — totals by energy type and end use
- Significant Energy Uses (SEUs) — systems accounting for most consumption or offering the greatest improvement potential
- Prioritised opportunity list — estimated savings, investment, and payback
- Data quality assessment — metering gaps and monitoring recommendations
- Baseline data — historical energy and operating data for subsequent M&V
From audit to verification
The audit begins the project; it does not close it. The typical path:
Energy audit (ISO 50002)
→ Improvement decision / ESCO contract
→ M&V plan (ISO 50015 + IPMVP)
→ Regression baseline (utility bills + degree days)
→ Verified savings (ISO 50047)The 12–24 months of billing data collected during an audit is exactly what an IPMVP Option C regression needs. At audit stage, a quick correlation between utility bills and degree days reveals whether a building is a good candidate for whole-facility verification — before you commit to a methodology.
We do not conduct energy audits. Where building audits identify weather-sensitive HVAC loads, degree day analysis helps scope opportunities; after the audit, billing-period-matched degree days become the independent variable in the verification regression.