The GHG Emissions Rating aims to increase transparency in the maritime industry by rating ships according to their efficiency, enabling users to make more informed decisions towards a more sustainable future.Read More
Unabated, shipping’s contribution to GHG emissions globally is projected to increase by an astounding 50% – 250% by 2050. In order to meet the long-term goals of limiting global warming to well below 2°C as outlined in the Paris Agreement, the substantial contribution of shipping to the world’s GHG emissions will need to be significantly reduced. RightShip’s GHG Emissions Rating offers a strategic market mechanism to lift the standard and efficiency of vessels worldwide.
RightShip’s GHG Emissions Rating was developed in response to the growing trend of global CO2 emissions and customer demand. It offers a systematic and transparent means of comparing the relative efficiency of the world’s shipping fleet.
The GHG Rating compares a ship’s theoretical CO2 emissions relative to peer vessels of a similar size and type using an easy to interpret A – G scale.
The Rating is increasingly being used by charterers, shipowners, financial institutions, and is also gaining momentum as an evaluation tool in various port incentive programs.Read More
As of early 2018, 85 organisations use the GHG Rating, including:
The GHG Rating is publicly accessible via www.shippingefficiency.org, or the enhanced version is available to customers via our vetting platform RightShip Qi.Read More
Access to Qi allows users to compare a ship’s environmental performance with other vessel data and fleet lists, as well as providing more background information and reporting tools.
A vessel's GHG Rating is presented using the standard European energy efficiency scale. The relative performance of a vessel is rated from A through to G, the most efficient being A, the least efficient being G.
Rather than adopting a ‘one size fits all’ approach, the GHG Rating provides comparison of a peer group of vessels, for example comparing a 100,000 DWT bulk carrier to a bulk carrier of a similar size and type.
Ship types for comparison align with the IMO’s documentation and guidance.Read More
Categories include bulk carriers, chemical tankers, container ships, crude & product tankers, cruise passenger and general cargo ships, LNG tankers, LPG tankers, refrigerated cargo ships and ro-ro cargo ships.
In terms of sizes for comparison vessels are compared to other vessels plus or minus 10% of their DWT.
The core measure for comparing the relative efficiency of the world’s fleet is grams of CO2 per tonne nautical mile.Read More
RightShip utilise one of two sources when determining an individual vessel’s efficiency:
As the two methods compare relative efficiency on the same basis, a like-for-like comparison of efficiency is achievable – as outlined in DNV GL’s review of RightShip’s methodology in 2015.
While the GHG Rating is relatively easy to interpret, the methodology used to calculate the GHG Rating is complex. The EVDI formula is as below:
The GHG Rating compares the relative efficiency of a ship using the EVDI (or EEDI is applicable).Read More
The peer group comparison is based on the number of standard deviations a vessel’s EVDI varies from the average for similar sized vessels of the same ship type.
In general, the distribution of the size group fit the following fixed percentiles of the data set.
The bell curve below illustrates the percentage distribution with the corresponding letter displayed in the coloured area under the curve.Read More
The x-axis is expressed as a count of standard deviations which matches the Size Score in the key.
For example, a 176,382 deadweight tonne bulk carrier has a GHG Rating of D, with a size score of -0.345.
It is considered alongside ships of plus or minus 10% of its deadweight, and is therefore compared to vessels within the range of 158,744 to 194,020 deadweight tonne.
In this case, as there are 1,060 ships in the peer group, approximately 735 are more efficient and 325 are less efficient than this particular vessel.
In January 2015 DNV GL commenced an independent methodology review of RightShip’s GHG Rating.Read More
The review was finalised in November 2015 and the key points included:
The executive summary of the outcomes of DNV GL’s methodology review can be found here.
The data used to calculate a vessel’s GHG Emissions Rating can be viewed:Read More
RightShip recognises that the reliability of its calculations directly correlates to the accuracy of source data. RightShip continues to work closely with ship owners, managers, yards and classification societies to validate the data used for the calculations.
The data utilised for the GHG Rating calculation is, as far as practicable, in line with the IMO guidelines (MEPC.245(66)) for EEDI calculation. RightShip obtains data for the GHG Rating from various industry sources as outlined below.
The source data for the GHG Rating is based on the hierarchy found in the table below.
As outlined in the DNV GL review, due to the pre-defined set of data assumptions applied to ‘non-verified’ vessels, there is an incentive for shipowners to update relevant data within Qi as it is likely to result in an improved GHG Rating.
|PREFERENCE / VERIFICATION LEVEL||DATA TYPE||DATA SOURCE / EXAMPLE|
|Most preferred / highest level of verification||Energy Efficiency Design Index||Classification Societies e.g. EEDI Technical Files
EEDI certificate (including supplement)
|Ship specific specifications||Ship-sourced data, e.g. sea trial and shop test supplied by the vessel owner / manager|
|Industry / third party data sources||Engine manufacturer's specifications
Data sourced from ship yards
|Least preferred / benefit from verification||IHS Maritime database|
IHS Maritime Database
The following documentation is requested to ensure the ship particulars are up to date:Read More
If the EEDI Technical File is not available, please provide the documentation outlined in the table below.
Upon receipt of the documentation, RightShip’s sustainability team will review and update the vessel particulars and provide the updated GHG Rating.
|DOCUMENTATION TYPE||RELATING FACTOR||RELEVANT DETAILS|
|Sea Trial||Vref Speed (Knots)||Trial Speed at Summer/ Scantling Load Draught at 75% Maximum Continuous Rating (MCR). In the form of a sea trial curve (calculated and/or model curves are acceptable)|
|Shop Test - Main and Auxiliary Engines||Number of Engines |
Power of engines (MCR)
Specific Fuel Consumption (SFC)
Fuel Type (test conditions)
|SFC for the Main Engine is read at 75% MCR
SFC for the Auxiliary Engines is read at 50% MCR
|Class Certificate and/or Ship Capacity Plan||Capacity||Deadweight (DWT)
TEU (if applicable)
CBM (if applicable)
|Ship classification notations||Common Structural Rules (include LBP and LWT)
Cubic-capacity correction factor
General cargo equipped with cranes
|Other documentation as appropriate||Innovative energy efficient technologies||Examples include waste heat recovery and shaft motor generator|
As stated above, SFC figures are sourced from vessel-specific shop tests or EEDI technical files.Read More
If the data is not provided by the ship owner, the values used in the calculation are based on the same assumptions used in the IMO GHG Study and / or detailed in IMO Circulars on the calculation of the energy efficiency measure as listed below.
|ENGINE AGE||MCRME (kW)||SFCME (g/kWh)|
|Pre 1983||> 15,000||205|
|5,000 to 15,000||215|
|5,000 to 15,000||195|
|5,000 to 15,000||185|
|5,000 to 15,000||185|
|MCRAE (kW)||SFCAE (g/kWh)|
|> 800 kW||220|
|< 800 kW||230|
If you would like to improve the GHG Rating of your vessel, and have had your vessel verified by RightShip, we suggest you seek advice from a suitable third party. This could include a Class Society, engine manufacturer or technology provider to advise of any energy efficiency measures that may improve your vessel’s rating.Read More
In advance of planned vessel upgrades you may like to contact firstname.lastname@example.org to discuss the potential improvements in GHG Rating. Some examples of voluntary energy efficiency measures or upgrades that may lead to a GHG Rating improvement include:
In order to demonstrate the improvements from any voluntary energy efficiency measures, RightShip requires a suitable statement / certificate from Class or appropriate third party detailing the work undertaken and any improvements in energy efficiency.
Please note that ‘operational measures’ (e.g. low friction paint, etc.) cannot usually be isolated from the EVDI equation and are normally not taken into account. It is also important to note that having one aspect of a vessel retrofitted / upgraded will not ensure the same for all other aspects. This is especially so in older vessels that require a re-sea trial, where we are comparing the results to the sea trial recently undertaken with that undertaken when the vessel was new. We therefore cannot guarantee that an upgrade or retrofit would necessarily improve the vessel’s GHG Rating.
Odfjell set about improving the fuel efficiency of their Kvaerner class vessels in close co-operation with MAN Diesel & Turbo, Grenaa Motorfabrik, ABB AS Turbocharging, and Marintek. RightShip were also consulted early in the project to understand the requirements for verification, and also the potential improvements in the GHG Rating.
The upgrades included new energy efficient propeller blades, rudder-bulb and technical upgrades of the main engine, turbo chargers and shaft generator. The combined upgrades reduced fuel consumption and emissions by over 20% – an outstanding outcome.
The Bow Clipper is now amongst the most energy-efficient chemical tankers in the world for its size, and is A rated for GHG emissions. The press release for this case study can be found here.