What Large Businesses Need to Know and Why Acting Early Matters

Phase 4 of the Energy Saving Opportunities Scheme (ESOS) is now underway, and for large UK organisations, the clock is already ticking.

While the structure of Phase 4 currently mirrors Phase 3, changes may still be introduced ahead of the compliance deadline. DESNZ have already floated the idea of introducing an additional progress update in ESOS Ph 4. Businesses that start planning now will be far better placed to manage audits smoothly, control costs, and reduce compliance risk. Not to forget, they can start to take advantage of energy-saving opportunities.

This insight is aimed at managers responsible for sustainability, energy, compliance and finance who want clarity, confidence and commercial value from their ESOS approach.

Does ESOS affect you?

ESOS is a UK government scheme that requires large organisations to carry out an energy assessment and site audits every four years. These audits assess energy use across buildings, transport, and industrial processes, in order to identify cost-effective energy-saving opportunities.

Organisations must comply with ESOS if in their FY ending on or before the qualification date;

• they employ 250 or more employees, or
• have an annual turnover above £44 million and an annual balance sheet total above £38 million

Key ESOS Phase 4 dates

• Qualification date: 31 December 2026
• Compliance deadline: 5 December 2027

Why early ESOS Phase 4 planning pays off

Although these dates may feel distant, waiting until late 2026 often results in higher costs, limited lead assessor availability, and unnecessary stress.

By locking in early, you’ll benefit from:

• Better commercial rates for audits, assessment and support
• Smoother scheduling with engineers and Lead Assessors
• More time to implement energy-saving opportunities
• Reduced risk of non-compliance or penalties
• Protection against any regulatory changes that may be introduced closer to the deadline.

So start your ESOS conversation now!

ISO 50001 certified? You still need to comply with ESOS

ISO 50001 certification does not exempt organisations from ESOS. Instead, it changes how compliance is demonstrated. Businesses with ISO 50001 must still complete mandatory elements such as:

• Energy audits where required
• Progress updates
• Action plans

Our energy team supports ISO 50001 certified organisations to align their management systems with ESOS Phase 4 requirements, ensuring full compliance while extracting valuable efficiency insights.

We can help you navigate your compliance with confidence.

ESOS Phase 4 in practice: unlocking real value

Many organisations have already used ESOS to drive meaningful and sustainable improvements.

“Working with Brownlow Utilities made ESOS compliance seamless and uncovered real energy saving opportunities.” – Gousto

In our work with Gousto, ESOS compliance was not just about meeting the scheme requirements. It was an opportunity to identify new efficiency measures that delivered tangible financial and operational benefits.

Turn ESOS compliance into opportunity for your business

ESOS should not be a tick-box exercise. With the right approach and the right partner, it can unlock long-term energy efficiency and environmental improvements, aligning with your wider sustainability and energy strategies.

Our in house team of ESOS Lead Assessors, energy engineers and consultants have successfully supported organisations through every phase of ESOS since its launch in 2014, turning ESOS into opportunity rather than being a regulatory burden!.

Get started with ESOS Phase 4

If your organisation qualifies for ESOS Phase 4, now is the time to act. This will help you

• Plan efficiently and avoid last minute pressures
• Navigate any regulatory changes with confidence
• Identify practical, actionable insights
• Start to realise cost saving and efficiency opportunities