The aim of this paper is to analyse the role of the industrial relations institutions in the ecological conversion of working environments and productions. The research question underpinning it is how and why trade unions and collective bargaining contribute to the greening of workplaces, and to make this process more just and participated, guaranteeing a positive impact on wages. To answer this question, the Author designs a cross-case synthesis on three case studies of companies that negotiated collective agreements where variable pay is linked to green objectives, such as energy efficiency and energy conservation.