Common ESOS Compliance Mistakes: What Businesses Need to Avoid
The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment scheme for qualifying organisations in the UK. While the basic principle of ESOS is straightforward, the compliance process can become complicated, particularly for businesses with multiple companies, sites, buildings, vehicles or energy-intensive operations.
With ESOS Phase 4 now underway and the compliance notification deadline of 5 December 2027 approaching, businesses need to make sure they understand exactly what is required.
Errors in energy data, corporate structure, assessment scope or reporting can all create unnecessary problems and potentially lead to enforcement action.
Here are some of the most common ESOS compliance mistakes businesses should avoid.
1. Assuming your business doesn’t qualify
One of the most common mistakes is assuming that ESOS does not apply to the business without properly checking the qualification criteria.
ESOS qualification is not simply based on whether an individual company is large. For businesses that form part of a corporate group, the assessment generally needs to consider the relevant UK undertaking and its wider corporate structure.
The first step should therefore be to establish:
- Which companies form part of the participant group
- Whether the organisation meets the qualification criteria
- Which entities need to be included
- The relevant energy consumption
- Whether any exemptions or alternative compliance arrangements apply
Getting this wrong at the beginning can affect the entire assessment.
2. Looking at only one company within a group
Corporate groups can be particularly challenging when it comes to ESOS.
A business may look at its largest operating company and conclude that it is below the relevant threshold, without considering the energy consumption of other companies within the group.
The ESOS qualification assessment needs to be considered at the appropriate group level.
This is why businesses with multiple subsidiaries should establish their corporate structure and responsibilities before beginning the energy assessment.
3. Using incomplete energy data
Good ESOS compliance depends on good energy data.
Businesses sometimes start the assessment process without having complete records covering the required reference period.
Energy consumption can come from a variety of sources, including:
- Electricity
- Natural gas
- Transport fuel
- Other fuels
- On-site generation
- Other relevant forms of energy
If information is missing, inconsistent or difficult to reconcile, the assessment can become significantly more complicated.
Businesses should therefore begin collecting and checking their energy data well before the compliance deadline.
4. Failing to identify all significant energy consumption
Another common mistake is concentrating on the most obvious energy-consuming areas while overlooking other significant sources.
For example, a business may focus heavily on its buildings while failing to properly consider transport, industrial processes or other significant energy consumption.
The ESOS assessment needs to provide an appropriate picture of the organisation’s energy use.
Understanding where the significant energy consumption actually occurs is essential when deciding which areas need to be assessed and where energy-saving opportunities may exist.
5. Choosing the wrong compliance route
ESOS allows qualifying organisations to use permitted compliance routes to cover their energy consumption.
However, businesses should not assume that a route used during a previous ESOS phase will automatically remain available.
This is particularly important for Phase 4, because the government has removed Display Energy Certificates (DECs) and Green Deal Assessments (GDAs) as alternative compliance routes.
Organisations should review the current Phase 4 requirements and determine which route or combination of routes is appropriate.
6. Leaving the Lead Assessor appointment too late
Where a Lead Assessor is required, businesses need to appoint an appropriately qualified professional from an approved register.
Leaving this until close to the compliance deadline can create unnecessary pressure.
A Lead Assessor may need to review energy audits, calculations, evidence and recommendations, so they should ideally be involved early enough to understand the scope of the assessment.
The right Lead Assessor can also help identify potential issues before the final compliance notification is submitted.
7. Treating the ESOS audit as a paperwork exercise
ESOS is about more than producing a report.
An effective energy audit should examine how energy is actually being used and identify realistic opportunities for improving efficiency.
Depending on the organisation, this may involve reviewing:
- Heating and cooling
- Lighting
- HVAC systems
- Motors and machinery
- Compressed air
- Refrigeration
- Building controls
- Building fabric
- Industrial processes
- Transport
- Energy management practices
A superficial assessment can miss significant opportunities to reduce both energy consumption and operating costs.
8. Failing to carry out appropriate site visits
For organisations using energy audits as their ESOS compliance route, appropriate site visits form part of the audit process.
This is important because energy consumption data alone cannot always explain why a building, process or piece of equipment is consuming energy.
A site visit can reveal practical issues that may not be obvious from bills and meter data, such as:
- Equipment operating unnecessarily
- Heating or cooling outside occupied hours
- Inefficient lighting
- Poor controls
- Compressed-air leaks
- Poor insulation
- Inefficient plant
- Equipment that is incorrectly configured
Physical inspection can therefore add considerable value to the assessment.
9. Producing recommendations without understanding the business
Energy-saving recommendations need to be relevant to the organisation.
A generic list of energy-efficiency measures may satisfy some of the basic reporting requirements, but it does not necessarily provide much practical value.
Businesses should be looking for recommendations that consider:
- Potential energy savings
- Financial savings
- Implementation costs
- Operational impact
- Payback
- Practical feasibility
- Carbon reduction
The most useful ESOS assessment should help management understand which opportunities deserve further investigation.
10. Assuming every recommendation has to be implemented
Another common misunderstanding is that ESOS requires businesses to implement every energy-saving recommendation identified by their assessment.
The purpose of ESOS is to identify energy-saving opportunities.
Businesses are not automatically required to implement every recommendation simply because it appears in their ESOS assessment.
However, Phase 4 places greater emphasis on reporting what happens after opportunities have been identified, including information about energy savings achieved and progress against action plans.
This makes it important for businesses to keep appropriate records of the actions they take following their assessment.
11. Forgetting about the ESOS evidence pack
The ESOS compliance notification is only part of the process.
Businesses must also maintain an appropriate ESOS evidence pack demonstrating how they have complied with the scheme.
The evidence pack should provide a clear record of the assessment and the information used to reach the relevant conclusions.
Failing to maintain proper evidence can make it much harder to demonstrate compliance if the organisation is subsequently subject to regulatory scrutiny.
12. Getting director sign-off wrong
ESOS requires the appropriate level of management involvement.
Before the notification is submitted, the relevant director or equivalent person needs to provide the required sign-off.
The exact requirements can depend on whether the Lead Assessor is internal or external.
This is another reason not to leave the compliance process until the last minute. The assessment needs to be completed, reviewed and approved before the notification can be submitted.
13. Waiting until the deadline
Perhaps the biggest ESOS mistake is leaving everything until the last minute.
The Phase 4 notification deadline is:
5 December 2027
That may sound like plenty of time, but large organisations can have substantial amounts of work to complete.
A typical process can involve:
Corporate structure → Energy data → Significant energy consumption → Compliance route → Lead Assessor → Energy audits → Site visits → Recommendations → Evidence pack → Sign-off → Notification
If information is missing or problems are discovered during the process, additional time may be required.
Starting early gives businesses much greater flexibility.
14. Treating ESOS as a compliance exercise rather than a cost-saving opportunity
Perhaps the most significant mistake is focusing exclusively on compliance.
ESOS can provide businesses with valuable insight into where energy is being consumed and where efficiency improvements may be possible.
For organisations with significant energy costs, even relatively small efficiency improvements can potentially produce meaningful annual savings.
The assessment should therefore be viewed as an opportunity to identify ways to:
- Reduce energy consumption
- Lower operating costs
- Improve energy efficiency
- Reduce carbon emissions
- Improve operational performance
How to avoid ESOS compliance mistakes
The easiest way to reduce the risk of mistakes is to plan the process well in advance.
A sensible approach is to:
- Confirm whether your organisation qualifies.
- Establish the correct corporate group structure.
- Gather and verify energy data.
- Identify significant energy consumption.
- Select the appropriate Phase 4 compliance route.
- Appoint a qualified Lead Assessor where required.
- Complete the necessary energy audits.
- Carry out appropriate site visits.
- Identify and evaluate energy-saving opportunities.
- Prepare the required evidence pack.
- Complete the necessary management sign-off.
- Submit the ESOS notification before the deadline.
- Keep track of actions and energy savings following the assessment.
Starting early makes it much easier to identify and resolve problems before they become urgent.
Prepare for ESOS Phase 4 now
ESOS compliance does not need to be complicated, but it does require careful planning.
The biggest problems tend to arise when businesses underestimate the amount of work involved, use incomplete information or rely on procedures from previous ESOS phases without checking the current Phase 4 requirements.
With the 5 December 2027 compliance deadline approaching, now is a good time to establish whether your organisation qualifies and start preparing the necessary information.
Carbon Numbers Investments can help businesses understand their ESOS obligations, assess their energy consumption and identify practical opportunities to reduce energy use and operating costs.
If you are preparing for ESOS Phase 4 and want to make sure your business is on the right track, contact Carbon Numbers Investments to discuss your requirements.
Frequently Asked Questions
What is the most common ESOS compliance mistake?
One of the most common problems is failing to properly establish whether the organisation qualifies and which companies need to be included. Incomplete energy data and leaving the assessment until late in the compliance period are also common issues.
What is the ESOS Phase 4 deadline?
The ESOS Phase 4 notification of compliance deadline is 5 December 2027.
Are DECs still valid for ESOS Phase 4?
No. Display Energy Certificates and Green Deal Assessments have been removed as alternative compliance routes for Phase 4.
Do ESOS recommendations have to be implemented?
Businesses are not automatically required to implement every recommendation identified through an ESOS assessment. However, Phase 4 introduces additional reporting requirements relating to energy savings and action plan progress.
Do I need an ESOS Lead Assessor?
Most qualifying organisations require a Lead Assessor unless a specific exemption applies. Organisations with total energy consumption below the relevant threshold, those with qualifying ISO 50001 coverage and organisations with zero energy consumption may fall within the relevant exceptions.
How can I prepare for ESOS Phase 4?
Start by confirming your qualification status, establishing the correct corporate structure, gathering energy data and determining the appropriate compliance route. If a Lead Assessor is required, appointing one early can help ensure the assessment is properly planned and completed before the deadline.
