Clean Shipping Index Verification

At the request of shipping companies, ClassNK acts as a verifier (Note 1), according to the Clean Shipping Index (Note 2). ClassNK performs ship verifications in accordance with the Clean Shipping Index Verification Guidelines.

The ship owner performs a self-assessment of the ship's environmental performance and then uploads this data into the Clean Shipping Index Database (Note 3).

Then, upon receipt of the owner's application the Society verifies the performance according to the Verification Guidelines and should full compliance be shown with the Guidelines, the Society will then upload the verification result into the Database and a Certificate of Verification is generated by CSI.



The objective is to verify the environmental performance of ten different types of ship, by evaluating the environmental impact of the ship's operation in five areas.

(Ship Type)

  • General Cargo Ships
  • Oil Tankers
  • Refrigerated Cargo Ships
  • Chemical Tankers
  • Bulk Carriers
  • Container Carriers
  • Product Tankers
  • RoRo Cargo Ships
  • LPG Carriers
  • Car Carriers


  • SOx and Particulate Matter (PM)
  • NOx
  • CO2
  • Chemicals (Antifouling agents, Stern tube oils, External hydraulic fluids, Gear oils for thrusters and/or controllable pitch (CP) propellers, Boiler/cooling water treatments, Cleaning agents, Refrigerants)
  • Water and wastes (Ballast water, Sewage/black water, Garbage, Sludge oils, Bilge water)


CO2 emissions are calculated according to the ship type by following either the EEOI Calculation Guidelines (Note 4) or the CCWG Guidelines (Note 5), and then this data is evaluated. The EEOI is applicable to all types of ships whereas CCWG Guidelines apply to container ships only.

Timing for Verification

Verification by the Society involves verification at the office of the shipping company and/or onboard verification. The verification can be conducted at the same time as classification surveys and statutory surveys, or during shipboard audits under ISO 140001.

Procedure for Verification

The procedure for verification is summarized in the below Flow Chart of Verification.

Flow Chart of Verification


Application for verification shall be made by completing and submitting the form "APPLICATION for Verification of Vessels under Clean Shipping Index" in addition to submitting the documents and records that are specified in "Documents To Be Submitted with Application".

APPLICATION for Verification of Vessels under Clean Shipping Index
Documents To Be Submitted with Application

Note 1:
The Society is approved by the Board of the Clean Shipping Network Association as a verifier of the Clean Shipping Index.
Note 2:
Clean Shipping Index (
Note 3:
Members of the Clean Shipping Network Association have the access to the Clean Shipping Index Database.
Note 4:
The calculation method for the energy efficiency operational indicator (EEOI) specified in IMO Guidelines (MEPC.1/Circ.684)
Note 5:
The calculation method for CO2 gas emissions developed by Clean Cargo Working Group

Contact Point for General Inquiries

NIPPON KAIJI KYOKAI Green Certification Department
4-7, Kioi-cho, Chiyoda-ku, Tokyo, 102-8567, Japan
Tel: +81-3-5226-2178 Fax: +81-3-5226-2179 e-mail: