In research on organizational environmentalism, there has been a repeated call for ways to go beyond the business case for sustainability frame. While the business case frame assumes that developing eco-friendly solutions can benefit firms financially, this article highlights the importance of challenging established understandings of sustainability. To this end, I introduce Deleuze’s distinction between morality and ethics. Morality involves passing judgements on the basis of values. Ethics provides an immanent evaluation of the principles by which specific solutions are considered sustainable. Analysing interviews with architects, building engineers and business developers, the article shows how these actors reflect on the values that form the basis of their practice, but also try to imagine new ways of working with sustainability. In conclusion, the article suggests that an immanent ethics of organizational environmentalism can allow for the values that inform environmental efforts in organizations to be evaluated as well as alternative visions of sustainability to be created.