It’s not all about numbers.

Words matter too.

Jenna Kim, Senior Auditor and Lead for Engage.

“Sustainability is multidisciplinary, spanning science, ethics and strategy. Choose specialists who understand ESG and sustainability as a distinct discipline, not accountants adapting financial audit skills to a fundamentally different challenge.”

Jenna Kim - Auditor and Engage Product Leader

Six reasons specialist sustainability assurance firms are better than financial accounting firms

Technical competence in environmental and social metrics

Traditional accounting firms train staff to audit financial transactions, revenue recognition and balance sheet items, not to assess the scientific validity of carbon sequestration claims, biodiversity net gain calculations or water stress assessments.

Sustainability assurance requires practitioners who understand life cycle analysis, greenhouse gas protocols, ecological impact methodologies and social impact measurement frameworks.

When reports include Scope 3 emissions across complex supply chains, nature-based solution credits or human rights due diligence findings, assurance requires environmental science expertise, sustainability credentials and technical ESG training, not accountants who have completed short courses in climate reporting.

The gap between financial audit skills and sustainability measurement expertise is significant and is reflected in the quality of assurance outcomes.

Supply chain and operational sustainability expertise

Sustainability performance does not sit in the finance function. It is embedded in operations, procurement, product design, logistics and supply chain management.

Specialist assurance providers like Speeki understand how to assess operational sustainability practices, including factory energy efficiency, responsible sourcing programmes, circular economy implementation and supplier sustainability screening.

We understand manufacturing processes, agricultural practices, logistics emissions and operational waste management in ways that accounting-trained auditors typically do not.

Where assurance requires site visits, interviews with operations teams, review of procurement processes or assessment of supplier audits, specialist firms bring operational sustainability expertise and speak the language of the business, not just accounting.

Fluency across multiple sustainability frameworks

Accounting firms are well versed in GAAP, IFRS and other financial reporting standards with long-established rules and practices.

Sustainability reporting operates in a more complex environment. Organisations often report across GRI, ISSB, CSRD, TCFD, SASB, CDP and sector-specific frameworks, each with different scopes, methodologies and disclosure requirements.

Specialist sustainability assurance providers like Speeki work within this multi-framework landscape every day. We understand how standards interact, where overlaps and conflicts arise and how to assess alignment across multiple reporting regimes.

We distinguish between disclosure frameworks and performance standards, voluntary and mandatory requirements, and stakeholder-focused and investor-focused approaches.

Materiality assessment through a sustainability lens

Financial materiality and sustainability materiality are based on different concepts. Financial auditors assess what may influence economic decisions reflected in the financial statements.

Sustainability materiality includes impact materiality and double materiality, requiring assessment of how an organisation affects people and the environment as well as how sustainability issues affect the business.

Specialist firms like Speeki understand stakeholder-inclusive materiality processes and support robust assessments that reflect diverse perspectives. We recognise that issues material for sustainability reporting may not meet financial audit thresholds.

Accounting-led approaches that rely on financial materiality alone risk overlooking critical environmental and social issues, resulting in assurance that is technically compliant but of limited strategic relevance.

Capability to assess qualitative and forward-looking information

Internal audit functions, regardless of their professionalism, face an inherent limitation. They are employed by the organisation, report within management structures and operate inside the governance framework they are asked to review.

External assurance providers like Speeki are structurally independent. Our opinions are subject to accreditation requirements, professional standards and external oversight, not internal management influence.

This independence allows us to challenge assumptions, question data quality and issue qualified conclusions without organisational pressure. Stakeholders recognise this distinction clearly: internal audit supports management, while external assurance serves the market.

Strategic sustainability insight, not compliance box-ticking

Accounting firms often approach assurance through a compliance lens: rule adherence, reconciliation and control documentation.

Specialist sustainability assurance providers like Speeki bring a strategic perspective developed through exclusive focus on ESG. We understand sector-specific sustainability trends, emerging practices, competitive positioning and the link between sustainability performance and long-term value.

Our work goes beyond verification. We benchmark against peers, identify gaps, highlight emerging risks and suggest practical improvements to strengthen both reporting quality and underlying performance.

When you engage Speeki, you work with specialists who treat sustainability as a strategic business issue, not as another compliance exercise. The difference is reflected in the depth and usefulness of the insights delivered alongside the assurance opinion.

Two women in an office discussing ESG, with a computer screen displaying the letters 'ESG' and related symbols like wind turbines, leaves, and currency.

Most sustainability reporting standards are based on words, not numbers

ESG and sustainability are about words and numbers coming together to tell a story.

Financial auditors excel at numbers, compliance and balance sheets, but sustainability assurance requires far more than checking calculations. ESG reporting is not accounting with a green label. It demands expertise in environmental science, social impact measurement, governance frameworks and the technical detail of carbon accounting, biodiversity assessment and stakeholder materiality.

When an assurance provider’s core skill set is debits and credits, they are not equipped to assess whether your Scope 3 methodology is sound, your social metrics are meaningful or your climate scenario analysis reflects real risk.

Build a stronger non-financial oversight strategy with Speeki