The use of the ESI is on a voluntary basis using self-declaration. Its objective is to encourage the use of clean ships and encourage shipping companies to anticipate and even exceed new regulatory requirements for air quality.
The Port of Rouen, in line with its actions in favour of the environment, joined the ESI initiative in 2013 and decided to reward shipping companies that operate the most environmentally friendly vessels in Rouen. Since 1 January 2013, regular or specialized liners, the most efficient in terms of reducing emissions into the atmosphere, have been offered the opportunity to obtain an "environmental reward".
In 2017, 104 ports of call were rewarded and the scheme was extended to cruise ships.
A methodology for evaluating the gain and effectiveness of the ESI approach is being defined in conjunction with ATMO Normandy as part of the Atmosphere Protection Plan.