How the Verification Process Works
From initial scope clarification to ZF-compliant verification report. Our supply chain sustainability audit process helps you choose between ISRS 4400 and ISAE 3000.
Verification Options
ZF accepts multiple verification levels. The right choice depends on whether the verification is only for ZF or also for other customers.
ISRS 4400
Agreed-Upon Procedures
We perform pre-defined procedures on your certificates and report factual findings — no opinion expressed. Typically 2 auditor days. Suitable for the ZF Recommendation level. Certificates must be retired with a ZF production reference.
Book Free ConsultationISAE 3000
Limited Assurance
Full sustainability assurance — we express a conclusion on your renewable energy claims. Required for ZF Minimum Requirement (mass balance, dedicated meter) and if the report serves other customers. Internationally recognized Scope 2 standard.
Book Free ConsultationRealistic Timeline
The actual duration depends strongly on the availability of contacts and documents.
Scope Clarification
Which entities, which plants, which approach. Identifying the right contractual partner.
Contract & Kickoff
Authorized signatory signs engagement letter. Kickoff meeting. Tailored document checklist.
Verification & Report
Document review, completeness declaration, formal verification report. Certificate retirement with ZF production reference in the registry.
Early Start Possible
Engagement and scope clarification can start as early as November. When documents (GOs, consumption data) arrive in February/March, only the verification step remains.
When Should You Start?
ZF's verification deadline is typically end of March. The earlier you start, the smoother the process.
Q4 (Oct to Dec)
Set up engagement and define scope before year-end.
January to February
Documents become available. GO cancellation statements arrive. Enough time for full verification.
March
Deadline is end of March. Compressed timelines, little buffer for missing documents.
Not Sure Which Approach You Need?
Book a free 30-minute consultation. We assess your situation and recommend the most efficient approach.