Energy audit: what it is, when it is mandatory, costs and differences from an energy assessment

An energy audit is a systematic procedure that reconstructs how an organisation uses energy, identifies where it is wasted, and quantifies possible measures, including costs, expected savings and payback periods.

For some businesses, it is a legal obligation that carries penalties. For all others, it remains the most reliable tool for deciding where to invest, provided it is based on measured data rather than estimates.

In brief:

• Large enterprises and energy-intensive companies are subject to the obligation every four years.
• Companies with a certified management system that includes a compliant audit are exempt.
• The audit must be submitted to ENEA through the dedicated portal, and failure to carry it out is punishable.
• Quality depends on measurement: without sub-metering and load profiles, the result is a list of generic measures.

What is an energy audit?

An energy audit is not simply a site inspection followed by a quotation. It is a regulated procedure defined by the UNI CEI EN 16247 series, divided into five parts: general requirements (Part 1), buildings (Part 2), processes (Part 3), transport (Part 4) and auditor competence (Part 5). The first four parts were updated in 2022.
The expected result is twofold. First, a reliable overview of consumption, broken down by different areas and uses, with energy performance indicators that allow comparisons over time. Second, a list of improvement measures, each with an estimated investment, expected savings and payback period.
Without the second part, it is not an energy audit but merely a consumption report. Without the first, the second cannot stand on its own.

Energy diagnosis and energy audit: what is the difference?

There is no substantial difference: they mean the same thing. “Energy audit” is the term used in European directives and technical literature, while “diagnosi energetica” is the term adopted by Italian legislation. Official documents use them interchangeably.
The real differences concern two other documents that are often confused with an energy audit:

• The EPC (Energy Performance Certificate) certifies a building's performance under standard operating conditions, is used for property sales and rentals, and does not contain an action plan based on actual consumption.
• A free energy check-up offered by energy suppliers or installers is a commercial assessment, often useful as an initial guide, but it does not meet EN 16247 requirements and does not satisfy the legal obligation.

Who is required to carry one out and how often

The obligation arises from Article 8 of Legislative Decree 102/2014: the first audit was due by 5 December 2015, with repetition every four years. Businesses that become subject to the obligation later follow their own individual deadline.
Audits must be submitted to ENEA through the audit102.enea.it portal, using the format and sector-specific spreadsheets required by the guidelines.
Note that the regulatory framework is evolving: with the transposition of the EED Directive 2023/1791, the criterion will change from company size to energy consumption.
Under the draft decree circulated in Italy, companies consuming between 10 and 85 TJ per year will have to carry out an audit, while those exceeding 85 TJ will need a certified management system under ISO 50001. As of the date of this article, the decree has not yet been published.

Penalties

This is not a formal obligation without consequences. Article 16 of Legislative Decree 102/2014 provides for:

• From €4,000 to €40,000 for failing to carry out the audit.
• From €2,000 to €20,000 for an audit that does not comply with the requirements.

In both cases, paying the penalty does not remove the obligation: the audit must still be carried out.

How an energy audit is carried out, step by step

• Data collection. Energy bills and contracts from previous years, production or activity data, floor areas, operating hours and equipment records.
• Historical consumption analysis. Breakdown by energy source and initial allocation to functional areas.
• Site inspection. Verification of the actual condition of systems, controls and operation, which often contradicts the documentation.
• Measurement campaign. Measurements at significant points for long enough to be representative. This is what distinguishes a serious audit from a paper-based exercise.
• Energy model and performance indicators. Mapping energy flows, calculating indicators and comparing them with sector benchmarks.
• Identification of measures. Each measure includes investment, expected savings and payback period, providing a cost-benefit analysis.
• Audit report and monitoring plan. The monitoring plan is not an optional attachment: it is part of the report required by ENEA guidelines.

Who can carry it out

A mandatory energy audit must be carried out by qualified professionals:

• ESCo companies certified under UNI CEI 11352, meaning energy service companies.
• EGE, or Energy Management Experts, certified under UNI CEI 11339, the same professional role discussed in our article about the energy manager.
• Energy auditors meeting the competence requirements of UNI CEI EN 16247-5.

There is no formal restriction for voluntary audits, but using a certified professional remains the simplest way to obtain a document that can also be used for regulatory purposes.

Energy audits in tertiary-sector buildings

The EN 16247 series dedicates a specific part to buildings, Part 16247-2, because auditing a building is not the same as auditing an industrial plant. Those managing offices, hotels, healthcare facilities or retail networks face four practical differences:

• There is no single unit of production. Performance indicators are based on floor area, opening hours, attendance or occupied rooms, and the choice of indicator determines comparability over time.
• Operational management has an enormous impact. In buildings, savings often come from system schedules and settings rather than machinery: these measures cannot be identified through an audit based only on monthly consumption.
• Sites are assessed in clusters. For dozens of similar retail outlets, ENEA guidelines provide sampling criteria: representative sites are audited and the results are extrapolated, making sample selection crucial.
• Comfort is a constraint. A measure that reduces consumption but worsens temperature or air quality is not sustainable in a hotel or residential care facility and must be assessed alongside environmental parameters.

How much it costs

There is no official price list, and it is wise to be wary of anyone who quotes a price before knowing what needs to be measured. The cost depends on four variables:

• The number of sites to audit and how similar they are, since similar sites can be assessed in clusters.
• The energy sources involved: electricity only, or also heating, gas, compressed air and water.
• The complexity of systems and processes, which determines how many measurements are required.
• The measurement campaign, including installed instruments, duration and the need for repeated site visits.

This is where the most significant price difference lies: a company that already measures its consumption can substantially reduce the most expensive part of the audit. Historical data is already available, the measurement campaign is shorter, and the auditor can focus on analysis rather than data collection.

Why many energy audits do not lead to savings

This is not merely a theoretical issue. In ENEA's assessments of mandatory audits submitted in November 2025, around 70% of non-compliances concerned the monitoring strategy: unspecified measurement points, campaigns that were too short, and missing or unrepresentative load profiles.
Issues with the technical and economic analysis also include lists of measures without an assessment of expected savings and, explicitly, measures copied from audits in different sectors.
There is another figure that matters even more. Audits submitted in 2025 indicate annual savings of around 29.7 ktoe already achieved, compared with a total potential of 68.2 ktoe: less than half of what the audits themselves had identified.
In our experience, the most common cause is always the same: the audit is a document, not a process. If nobody measures consumption afterwards, there is no way to know which measures worked, and the next audit starts again from estimates.

Energy audits, management systems and certifications

The three approaches fit together better than they might appear:

• The energy audit is the periodic analysis that provides a snapshot of consumption and potential savings.
• ISO 50001 is the ongoing process that turns that analysis into continuous management and exempts a company from the audit obligation when it includes a compliant audit.
• LEED, BREEAM and WELL certifications provide market recognition and require much of the same data.

This is complemented by the evolving regulatory framework of the EPBD Directive, which points in the same direction: understanding the actual performance of buildings and documenting it.

Tools: an energy audit is more effective when the building is metered

The quality of an audit depends on the data available when the auditor arrives. With utility bills alone, much of the work is estimation; with a year of data for each utility, the work becomes analysis.
UTwin's energy management software addresses precisely this need: the provision of smart meters and IoT sensors for energy, water, gas and environmental parameters; cloud-based historical data storage; visualisation on the building model; automatic anomaly alerts; and remote system adjustments based on outdoor weather and occupancy.
The real value, however, comes after the audit. Once the measures have been implemented, energy consumption monitoring makes it possible to verify actual savings, correct what did not work and approach the next audit with real figures instead of another list of estimates.
The integrated maintenance software tracks completed work, providing the documentation required at each inspection.

Frequently asked questions

• What is the difference between an energy audit and an EPC?

  An EPC certifies a building's energy performance calculated under standard operating conditions and is required for sales, rentals and building-related compliance. An energy audit analyses an organisation's actual consumption and identifies improvement measures with their costs, savings and payback periods. These are different documents with different purposes.

• When does the obligation to carry out an energy audit expire?

  The obligation under Legislative Decree 102/2014 applies every four years, starting from the first deadline of 5 December 2015. Businesses that became subject to the obligation later follow their own individual deadline. With the transposition of the EED Directive, the criterion will shift from company-size parameters to annual energy consumption.

• Who can sign a mandatory energy audit?

  ESCo companies certified under UNI CEI 11352, Energy Management Experts (EGE) certified under UNI CEI 11339, and energy auditors meeting the requirements of UNI CEI EN 16247-5.

• How much does an energy audit cost?

  There is no fixed price list: the cost depends on the number of sites, energy sources, system complexity and scope of the measurement campaign. A company that already has an active monitoring system pays less because much of the data collection has already been completed.

• If I have ISO 50001 certification, do I still have to carry out an energy audit?

  No, provided that the management system includes an energy audit compliant with Annex 2 of Legislative Decree 102/2014. Article 8 of the decree provides this exemption for systems compliant with ISO 50001, EMAS and EN ISO 14001.

Where to start

If the deadline is approaching, the question to ask is not whom to hire for the audit, but how well the company measures its energy use today. A year of data for each utility changes the outcome: the audit becomes a defensible action plan instead of a document to file away, and savings verification becomes automatic.