Sustainability Assurance - Strengthening GHG Emissions Reporting Across Multi-Site Operations

Client: Mastermelt

Mastermelt is an international precious metals recovery and refining business operating across the UK, Germany and Singapore.  

Acclaro performed independent limited assurance over Mastermelt’s 2025 greenhouse gas inventory, covering Scope 1, Scope 2 and relevant reported Scope 3 emissions. 

The engagement also included pre-assurance readiness support and practical improvement recommendations to strengthen the evidence, methodologies, controls and governance supporting future reporting. 

Key outcomes

Independent limited assurance completed over Mastermelt’s 2025 greenhouse gas inventory.  

• A credible internal emissions baseline established across its international operations.  
• Clear priorities identified across data, methodologies and reporting controls.  
• Evidence expectations strengthened for significant emissions calculations.  
• Mastermelt better prepared for future reporting and assurance cycles. 

The challenge

Mastermelt’s greenhouse gas inventory required information to be collected and consolidated across operations in the UK, Germany and Singapore. 

The key challenges included: 

• Maintaining consistent GHG reporting across international operations
• Strengthening evidence supporting Scope 1, Scope 2 and Scope 3 emissions  
• Applying appropriate methodologies and emission factors across different jurisdictions
• Managing estimates and judgement within shipping and other Scope 3 categories
• Improving documentation, ownership and controls supporting the reporting process

What Acclaro delivered

• Independent Limited Assurance under ISAE 3410 and ISAE 3000 (Revised). 
• Pre-assurance readiness workshops covering assurance expectations, evidence requirements and teams responsibilities. 
• We identified priority improvements across evidence, methodologies, controls, governance and future reporting 

“The Mastermelt Group commissioned Acclaro Advisory for our first-year GHG verification. Jose & the team have provided clear, practical guidance throughout our GHG assurance process, including a focused workshop that helped our team understand expectations and strengthen our approach. Their ability to translate complex requirements into actionable steps is helping us improve data quality, documentation, and overall confidence in our reporting. We don’t hesitate to recommend them for any consultancy and assurance works.” 

Sean Critchlow, Environmental, Safety & Quality Manager

Looking ahead

Mastermelt now has a clearer internal baseline, defined priorities for improving its reporting methodologies and controls, and greater readiness for future assurance cycles. 

Acclaro continues to support organisations through pre-assurance readiness, independent limited assurance and practical improvement actions designed to strengthen sustainability reporting.