Purpose Public facilities management (FM) is in the unique position of aligning building projects and FM with the policies of sustainable development at societal level. However, sustainable facilities management (SFM) is an emergent profession, and there is a need to build a code of conduct for SFM in FM organisations. The purpose is to develop and test a workshop based concept for collective building of capabilities targeting in-house FM organisations, in particular public in-house FM organisations. Design/methodology/approach This research explores the role of public facilities managers and examines how an empowerment process can help FM employees develop collective competences for SFM. The methodologies used are literature review, and a 3–year-long action research process in the Danish local authority, Albertslund, which is internationally recognised for its innovative and green profile. Findings This paper describes the phenomenon of public SFM imbedded in societal steering paradigms and suggests a framework for a sustainable FM code of conduct. The suggested “Next generation SFM code of conduct” support the employees in taking a proactive strategic position in which translation between politics, strategy, tactics and daily practice becomes the basis for prioritisation and decision-making. The capabilities needed is FM knowledge (including FM know-how, understanding of technologies for sustainability and public governance); it is the FM code of conduct, and it is control of own practice to be obtained through strategies and planning, collaboration and education. Research limitations/implications This study is based on findings in a single local authority, why the findings are primary valid for concept development to be further developed and tested. However, the local authority of Albertslund is recognised as a front runner in green FM, why this case, compare to other cases, represents a relatively mature thinking in terms of FM contribution to sustainability at societal level. When this FM organisation express a need for developing collective competences for sustainability in FM, it can be assumed that less mature FM organisations needs it even more. The findings seem relevant beyond public FM organisations. Practical implications The produced framework for a sustainable FM code of conduct is useful for educational purposes as well as for strategic decision about FM organisations collective competence profile. The use of workshops for the building of collective competences might be useful for many other organisations and not only public FM organisations. Social implications Public FM organisations manage significant shares of existing buildings and can be a driver for societal change if they have the capabilities. This paper provides an answer to how these collective capabilities can be build within an organisational development process, through dialogue and collective reflections. Originality/value This paper is a pioneer in understanding the capabilities needed in FM organisations to take leadership in an integration of sustainability in FM processes.