As ESG and climate disclosures become mandatory, investors and regulators want to know they can rely on the numbers. External assurance gives that confidence, and in Singapore and other markets assurance of GHG emissions is being phased in as part of mandatory climate reporting. GreenCo offers sustainability report verification and assurance performed by a CPA (Practising), together with practical readiness support so your first assurance engagement goes smoothly.
What Is Sustainability Assurance?
Sustainability assurance is an independent examination of sustainability information, such as GHG emissions, ESG KPIs or a full sustainability report, by a qualified practitioner who then issues a formal conclusion.
- Limited assurance – a moderate level of assurance based mainly on enquiry and analytical procedures. The conclusion is expressed in negative form ("nothing has come to our attention..."). It is the most common starting point and is the level being phased in for Scope 1 and Scope 2 emissions in Singapore.
- Reasonable assurance – a high level of assurance, similar to a financial statement audit, with more extensive testing of data and controls.
Assurance Standards: ISAE 3000 and the New ISSA 5000
- ISAE 3000 (Revised) – the long-established international standard for assurance engagements other than audits of financial information, widely used for sustainability reports. ISAE 3410 covers GHG statements.
- ISSA 5000 – the IAASB's new global standard for sustainability assurance, published in November 2024. It is effective for sustainability information reported for periods beginning on or after 15 December 2026, and will replace ISAE 3000 and ISAE 3410 for sustainability engagements.
Companies whose reporting periods begin after mid-December 2026 should expect assurance to follow ISSA 5000, with stronger focus on materiality, data controls and evidence.
Assurance Readiness Checklist
- Define scope – which indicators, entities and periods will be assured.
- Document methodologies – boundaries, calculation methods, emission factor sources and assumptions.
- Build an audit trail – link every reported figure to source data such as invoices, meter readings and supplier records.
- Strengthen controls – data owners, review and sign-off steps, and change logs.
- Run a pre-assurance review – test data and fix gaps before the formal engagement.
- Plan the timeline – align fieldwork with your reporting deadlines.
How GreenCo Helps
- Pre-assurance readiness reviews and gap analysis.
- Data process and internal control design for ESG and GHG data.
- Sustainability report verification and assurance performed by a CPA (Practising), in accordance with internationally recognised assurance standards.
- Recommendations to improve data quality year on year.
Related reading: Sustainability Report Verification and Assurance (video) · External Assurance for Climate Reporting in Singapore
Why Appoint GreenCo for International Sustainability and ESG Advisory?
Since 2016, GreenCo has been trusted by public and private companies and multinational companies for reliable, standards-based ESG and sustainability advisory. We have supported more than 80 listed companies in Hong Kong, Singapore, Mainland China and South Korea, alongside private companies, IPO candidates and multinational groups.
- International standards expertise – GRI, ISSB (IFRS S1 and S2), HKEX and SGX listing rules, the GHG Protocol, ISO 14064 and ISAE 3000.
- All-round, one-stop advisory – strategy, materiality, reporting, GHG accounting, climate risk, ESG ratings, training and assurance under one roof.
- Built from scratch, with you throughout – we can build your ESG framework, data processes and reports from the ground up, and our consultants stay hands-on from kick-off to sign-off.
- Finance-grade rigour – our team combines accounting, investment and risk qualifications, so your ESG numbers stand up to auditors, regulators and investors.
- Professional judgement, with AI as a tool – we use AI and digital tools for efficiency, but every conclusion is reviewed and owned by qualified consultants.
- Assurance capability – assurance services performed by a CPA (Practising) in accordance with ISAE 3000.
Our Team's Professional Credentials
- Fellow Certified Public Accountant (FCPA)
- Chartered Financial Analyst (CFA) – CFA Institute
- Financial Risk Manager (FRM) – Global Association of Risk Professionals (GARP)
- Certified ESG Analyst (CESGA)
- Sustainable Investing Certificate – CFA Institute
- GRI Certified Professional
- Practitioner Member – Institute of Sustainability and Environmental Professionals (ISEP)
- GRI Certified Sustainability Professional – Global Reporting Initiative (GRI)