Delivering ESOS Phase 3 support through specialist partnership

Sustainability
May 25, 2026

As energy regulations continue to evolve, organisations face increasing pressure to demonstrate compliance and show meaningful progress on efficiency and sustainability. For member firms like Macalvins, this means responding quickly to client needs and bringing in specialist expertise when requirements fall outside traditional accounting and advisory services.

ESOS level 3
The challenge

When one of their corporate clients required support with Phase 3 of the Energy Savings Opportunity Scheme (ESOS), Macalvins recognised that the updated rules and complexity of the client’s energy use required dedicated technical input and formal oversight from a qualified ESOS Lead Assessor.

To ensure the client received accurate, timely guidance, Macalvins turned to the PrimeGlobal community to access specialist expertise.

The PrimeGlobal connection

Through PrimeGlobal, Macalvins was introduced to Boxfish, a specialist sustainability consultancy and PrimeGlobal Alliance Partner, via member firm Henderson Loggie.

This connection enabled Macalvins to bring in ESOS Phase 3 expertise quickly and seamlessly, strengthening the technical delivery while maintaining their role as the client’s trusted adviser.

How the collaboration worked

From the outset, Macalvins and Boxfish agreed a clear delivery model:

  • Macalvins led the client relationship and overall engagement
  • Boxfish provided specialist ESOS Phase 3 expertise and technical oversight

This collaborative approach ensured the client benefited from both continuity of advice and deep technical capability, with clear ownership and consistent momentum throughout the process.

Muntazir Bhimji 2 jpg
‘This project showed the real strength of the PrimeGlobal community We were introduced to Boxfish and were able to draw on their ESOS Phase 3 expertise straight away, giving our client fast, accurate guidance on the updated requirements and confidence in their compliance approach.’ Muntazir Bhimji, Partner, Macalvins Ltd
Specialist input with practical outcomes

Boxfish supported the engagement with targeted ESOS Phase 3 expertise, including:

  • Confirming organisational scope and identifying key areas of energy consumption
  • Carrying out on-site energy auditing and analysis of energy use data
  • Providing ESOS Lead Assessor oversight, including formal review and sign-off
  • Setting out clear next steps to support energy efficiency improvements, carbon reduction, and cost savings

By integrating this specialist input, the client was able to progress through ESOS Phase 3 with clarity, confidence, and a structured, compliant approach.

Outcomes for the client and firms
  • The client achieved a clear and compliant ESOS Phase 3 approach
  • Macalvins retained its position as the trusted adviser, without needing to outsource the relationship
  • Specialist expertise was accessed quickly through PrimeGlobal
  • Technical capability was enhanced without adding complexity to the engagement
Why this matters for member firms

This example highlights the value of PrimeGlobal collaboration. As client needs become more specialised, access to trusted expertise across the network allows firms to:

  • Expand their service offering without building capability in-house
  • Strengthen client relationships by delivering broader solutions
  • Respond quickly to complex or technical requirements
  • Create new opportunities for collaboration and fee generation
A model for delivering more through PrimeGlobal

This engagement demonstrates how member firms and Alliance Partners can work together to deliver joined-up solutions for clients.

For Macalvins, the collaboration expanded technical capability while keeping delivery seamless and client-led. For Boxfish, it showed how specialist sustainability expertise can be integrated into wider advisory engagements.

Most importantly, the client benefited from a fully supported, compliant outcome delivered through a single trusted relationship.

As regulatory requirements continue to evolve, this partnership-led model provides a practical way for PrimeGlobal member firms to meet increasingly complex client needs with confidence.

About Boxfish

Boxfish is a sustainability and utility consultancy helping organisations cut emissions, reduce energy costs, and stay compliant as regulations evolve.

They support professional service firms and their clients with carbon footprinting, SECR and ESOS compliance, ESG support, net zero roadmaps, and energy efficiency improvements.

Their approach combines technical expertise with practical delivery, working alongside firms as a trusted partner to turn complex requirements into clear, measurable outcomes.

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